Conjoint Professor Peter Greer

Conjoint Professor Peter Greer

Conjoint Professor

School of Mathematical and Physical Sciences (Physics)

Rethinking radiation therapy

Combining expertise in the fields of physics, medicine, and IT, Peter Greer and his team are marrying research and practice.

Working quietly behind the scenes in every radiation oncology centre, are a group of scientists who manage the extremely intricate processes involved in the delivery of radiation oncology.

Medical physicists work to implement and develop imaging techniques to delineate tumours, dose calculation algorithms to calculate complex doses, and intensity modulated radiation delivery to deliver highly tailored dose distributions of radiation therapy.

Peter currently holds a full-time research position leading a medical physicis research group at the Calvary Mater Newcastle Hospital and University of Newcastle.

His work aims to improve the treatment of cancer patients with radiation therapy and enable high quality effective treatments.

Much awarded, Peter is recognised as a world leader in the field of radiation dosimetry with flat-panel imaging devices, and has twice taken the role of Scientific Director for the major international conference in radiotherapy treatment imaging.

MRI planning and delivery

Along with surgery, radiation oncology is a frontline treatment for cancers.

Delivered either internally of externally depending on the tumour site, radiotherapy technology, which uses high-energy x-ray beams to sterilise DNA in tumors, continues to improve.

Not only do medical physicists ensure all aspects of treatment are precisely calculated and delivered, but they also drive the development of improved technology and techniques through research.

Investigating MRIs as a potential game changer in radiation oncology, Peter and his team have been working in collaboration with CSIRO Biomedical Imaging Research Group at the Australian E-Health Research Centre since 2005.

“MRI is fantastic for delineating the tumours and the normal tissues,” Peter says.

“But we are currently still reliant on CT scans for calculating the dose.”

A true pioneer in this area, Peter has developed the first atlas-based deformable image registration method to map realistic electron densities to MRI scans for dose calculations.

“If we can avoid the CT scanning, and just plan directly with the MRI, that would cost less for the health system, it's better for the patient, and it would be more accurate treatment as well.”

Having proven effective for treatment dosage calculations in retrospective studies, Peter and his team are now beginning to implement the improved MRI-only system for prospective prostrate tumour patients in the clinic.

Watchdog

Collaborating with Cancer Care Manitoba and Memorial Sloan Kettering, Peter and his team are also developing Watchdog, a real-time verification imaging system.

Conventional radiotherapy has been reliant on the accuracy of pre-emptive dosage calculations, with no way of verifying delivery during treatment.

“Major errors are very rare in Australia,” Peter notes.

“But minor errors are more frequent, and underdosing or overdosing could compromise treatment.”

A prestigious grant from The American Society for Radiation Oncology (ASTRO) recognises the massive positive impacts a real-time verification system could have on patient safety.

“We are now verifying the delivery using the imaging system in a movie mode,” Peter explains

“The real-time measurement allows for immediate checking, and if something is not right you just stop, and it really doesn't require any extra effort.”

The National Health and Medical Research Council (NHMRC) has also contributed to the research, funding the team to develop a successful prototype into a system that can be used by any radiation oncology centre.

Remote auditing

Also based at the Calvary Mater Hospital is The Trans-Tasman Radiation Oncology Group (TROG), a global leader in radiotherapy research.

With TROG research threatened by ever increasing costs associated with sending physicists to remote multicenter research sites to ensure treatment uniformity, Peter came up with a solution.

The Virtual EPID Standard Phantom Audit (VESPA) uses imaging systems to record EPID images then sent electronically to TROG for remote dosing analysis and audit.

So successful have trials of this system been that Peter and his team are now assisting TROG’s UK equivalent - The Cancer Research UK and UCL Cancer Trials Centre - to trial this method of remote auditing.

Possibilities and Paths

Peter was drawn to medical physics because he believed this path would include ever changing challenges, and the opportunity to see research implemented.

“Everything changes so quickly, there is always new technology, so we have to be constantly thinking and upgrading our knowledge,” Peter says.

He credits his extensive experience on the clinical coalface as his inspiration for ideas regarding optimal treatments.

“Sometimes things are obvious and lots of people are looking at them,” he says.

“But sometimes it is just a matter of working in an area for a while, and then seeing the possibilities and paths.”

Asked if he is ever overwhelmed by the necessity of his clinical work, Peter responds immediately.

“There is always hope, and I am grateful my work is making a positive difference.”

Peter Greer

Rethinking radiation therapy

Combining expertise in the fields of physics, medicine, and IT, Peter Greer and his team are marrying research and practice.

Read more

Career Summary

Biography

Peter currently holds a full-time research position leading medical physics research at the Calvary Mater Newcastle Hospital and University of Newcastle. He graduated with a PhD in medical physics from the University of Adelaide in 2001. His work broadly aims to improve the treatment of cancer patients with radiation therapy and enable high quality effective treatments.

He has established a strong track record of translating research funding into successful outcomes. Several aspects of his research are currently being developed into commercial products for radiation oncology and medical imaging. He has received several awards including Early Career Researcher of the Year from the Hunter Medical Research Institute in 2011 - the premier award for early career medical research in the region. 

Research Expertise
Approximately half of all cancer patients receive radiation therapy. It is a major frontline treatment for cancer along with surgery and is often complemented by chemotherapy. High energy radiation beams are used to damage the DNA of cancer cells in solid tumours while minimising the normal tissue damage to surrounding organs. The radiation can be delivered externally using medical linear accelerators (teletherapy) or internally using radioactive sources (brachytherapy).

Modern radiation therapy is extremely sophisticated with imaging techniques such as MRI, CT, PET used for delineating tumour targets, complex dose calculation algorithms to plan the treatments and highly tailored dose distributions delivered using intensity modulated radiation beams. Medical physicists play a key role in all aspects of radiation oncology and drive the development of improved technology and techniques through research.

Peter has been conducting research since 2005 to improve radiation therapy planning with MRI. In collaboration with CSIRO Biomedical Imaging Research Group at the Australian E-Health Research Centre he has developed the first atlas-based deformable image registration method to map realistic electron densities to MRI scans for dose calculations. This could lead to the use of MRI scans directly for radiation oncology prostate planning and adaptive treatment to reduce uncertainties in the planning of treatments. He currently has an active research program using the state-of-the-art Calvary Mater 3T Skyra MRI scanner installed in April 2011 to improve radiation therapy planning. 

Peter is recognised as a world leader in the field of radiation dosimetry with flat-panel imaging devices, investigating methods to measure the dose received by patients during treatment. He has been twice the Scientific Director for the major international conference in radiotherapy treatment imaging. He has been awarded the Varian Prize for research in this field and is regularly invited to give presentations at national and international conferences and workshops. 

Teaching Expertise
Peter teaches medical physics courses at 4th year level. He has supervised many research higher degree students.

Administrative Expertise
Peter was Honorary Treasurer of the Australasian College of Physical Scientists and Engineers in Medicine, the professional body representing around 600 medical physicists and engineers working in medicine in Australia and New Zealand. He has been twice the Scientific Director for the major international conference in radiotherapy treatment imaging. He was Track Chair for the radiotherapy verification stream for the World Congress on Medical Physics and Bioengineering in 2012. Peter manages his own research group based at the Calvary Mater Newcastle, including staff supervision, management of budgets and reports.

Collaborations
Current collaborations include: - CSIRO E-Health Centre, Biomedical Imaging Group (MRI based treatment planning) - CancerCare Manitoba (Real-time dose verification of radiation therapy treatments) - University of Sydney (A/V Biofeedback for lung MRI imaging, dose verification for MRI-linac, Development of next-generation radiotherapy imaging devices)


Keywords

  • MRI based planning
  • dose verification
  • electronic portal imaging
  • medical physics

Fields of Research

Code Description Percentage
029903 Medical Physics 80
090399 Biomedical Engineering not elsewhere classified 10
110399 Clinical Sciences not elsewhere classified 10

Professional Experience

Membership

Dates Title Organisation / Department
Treasurer - Australasian College of Physical Scientists and Engineers in Medicine Australasian College of Physical Scientists and Engineers in Medicine
Australia
Ordinary Member - Australasian College of Physical Scientists and Engineers in Medicine Australasian College of Physical Scientists and Engineers in Medicine
Australia
1/03/2011 - 1/12/2011 Member NHMRC Grant Review Panel
Australia

Professional appointment

Dates Title Organisation / Department
Accredited Physicist Australasian College of Physical Scientists and Engineers in Medicine
Australia

Awards

Distinction

Year Award
2014 Fellowship of the ACPSEM
Australasian College Physical Scientists Engineers in Medicine

Research Award

Year Award
2010 Early Career Researcher of the Year
HMRI
2009 3D Segmentation Challenge for Clinical Applications
Medical Image Computing and Computer Assisted Intervention Society (MICCAI Society)
2007 Best presentation in Radiation therapy
Varian Medical Systems, Inc.

Invitations

Distinguished Visitor

Year Title / Rationale
2015 Invited Speaker - 3rd ESTRO Forum
Organisation: European Society for Radiation Oncology

Speaker

Year Title / Rationale
2012 EPID for pre-treatment VMAT verification
Organisation: International Conference on 3D Dosimetry
2012 EPID based QA
Organisation: World Congress on Medical Physics and Bioengineering
2012 33rd National Conference
Organisation: Association of Medical Physicists of India
2010 Challenges for Verification of IMRT
Organisation: 16th International Conference on Solid State Dosimetry
Edit

Publications

For publications that are currently unpublished or in-press, details are shown in italics.


Journal article (127 outputs)

Year Citation Altmetrics Link
2017 Fuangrod T, Greer PB, Zwan BJ, Barnes MP, Lehmann J, 'A novel and independent method for time-resolved gantry angle quality assurance for VMAT.', J Appl Clin Med Phys, (2017)
DOI 10.1002/acm2.12129
2017 Nguyen DT, O'Brien R, Kim J-H, Huang C-Y, Wilton L, Greer P, et al., 'The first clinical implementation of a real-time six degree of freedom target tracking system during radiation therapy based on Kilovoltage Intrafraction Monitoring (KIM).', Radiother Oncol, 123 37-42 (2017)
DOI 10.1016/j.radonc.2017.02.013
Citations Scopus - 2Web of Science - 2
Co-authors Jarad Martin
2017 Legge K, Greer PB, Keall PJ, Booth JT, Arumugam S, Moodie T, et al., 'Technical note: TROG 15.01 SPARK trial multi-institutional imaging dose measurement.', J Appl Clin Med Phys, (2017)
DOI 10.1002/acm2.12151
Co-authors John Oconnor, Jarad Martin
2017 Zwan BJ, Barnes MP, Hindmarsh J, Lim SB, Lovelock DM, Fuangrod T, et al., 'Commissioning and quality assurance for VMAT delivery systems: An efficient time-resolved system using real-time EPID imaging: An', Medical Physics, 44 3909-3922 (2017) [C1]

© 2017 American Association of Physicists in Medicine. Purpose: An ideal commissioning and quality assurance (QA) program for Volumetric Modulated Arc Therapy (VMAT) delivery sys... [more]

© 2017 American Association of Physicists in Medicine. Purpose: An ideal commissioning and quality assurance (QA) program for Volumetric Modulated Arc Therapy (VMAT) delivery systems should assess the performance of each individual dynamic component as a function of gantry angle. Procedures within such a program should also be time-efficient, independent of the delivery system and be sensitive to all types of errors. The purpose of this work is to develop a system for automated time-resolved commissioning and QA of VMAT control systems which meets these criteria. Methods: The procedures developed within this work rely solely on images obtained, using an electronic portal imaging device (EPID) without the presence of a phantom. During the delivery of specially designed VMAT test plans, EPID frames were acquired at 9.5 Hz, using a frame grabber. The set of test plans was developed to individually assess the performance of the dose delivery and multileaf collimator (MLC) control systems under varying levels of delivery complexities. An in-house software tool was developed to automatically extract features from the EPID images and evaluate the following characteristics as a function of gantry angle: dose delivery accuracy, dose rate constancy, beam profile constancy, gantry speed constancy, dynamic MLC positioning accuracy, MLC speed and acceleration constancy, and synchronization between gantry angle, MLC positioning and dose rate. Machine log files were also acquired during each delivery and subsequently compared to information extracted from EPID image frames. Results: The largest difference between measured and planned dose at any gantry angle was 0.8% which correlated with rapid changes in dose rate and gantry speed. For all other test plans, the dose delivered was within 0.25% of the planned dose for all gantry angles. Profile constancy was not found to vary with gantry angle for tests where gantry speed and dose rate were constant, however, for tests with varying dose rate and gantry speed, segments with lower dose rate and higher gantry speed exhibited less profile stability. MLC positional accuracy was not observed to be dependent on the degree of interdigitation. MLC speed was measured for each individual leaf and slower leaf speeds were shown to be compensated for by lower dose rates. The test procedures were found to be sensitive to 1 mm systematic MLC errors, 1 mm random MLC errors, 0.4 mm MLC gap errors and synchronization errors between the MLC, dose rate and gantry angle controls systems of 1. In general, parameters measured by both EPID and log files agreed with the plan, however, a greater average departure from the plan was evidenced by the EPID measurements. Conclusion: QA test plans and analysis methods have been developed to assess the performance of each dynamic component of VMAT deliveries individually and as a function of gantry angle. This methodology relies solely on time-resolved EPID imaging without the presence of a phantom and has been shown to be sensitive to a range of delivery errors. The procedures developed in this work are both comprehensive and time-efficient and can be used for streamlined commissioning and QA of VMAT delivery systems.

DOI 10.1002/mp.12387
Co-authors John Oconnor
2017 Keall P, Doan TN, O'Brien R, Booth J, Greer P, Poulsen P, et al., 'Stereotactic prostate adaptive radiotherapy utilising kilovoltage intrafraction monitoring: the TROG 15.01 SPARK trial', BMC CANCER, 17 (2017)
DOI 10.1186/s12885-017-3164-1
Co-authors Jarad Martin
2017 Barnes MP, Greer PB, 'Evaluation of the TrueBeam machine performance check (MPC) beam constancy checks for flattened and flattening filter-free (FFF) photon beams', JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS, 18 139-150 (2017) [C1]
DOI 10.1002/acm2.12016
Citations Web of Science - 1
2017 Barnes MP, Greer PB, 'Evaluation of the truebeam machine performance check (MPC): mechanical and collimation checks', JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS, 18 56-66 (2017) [C1]
DOI 10.1002/acm2.12072
2017 Barnes MP, Greer PB, 'Evaluation of the truebeam machine performance check (MPC) geometric checks for daily IGRT geometric accuracy quality assurance', JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS, 18 200-206 (2017) [C1]
DOI 10.1002/acm2.12064
2017 Legge K, Greer PB, O'Connor DJ, Wilton L, Richardson M, Hunter P, et al., 'Real-time in vivo rectal wall dosimetry using MOSkin detectors during linac based stereotactic radiotherapy with rectal displacement', RADIATION ONCOLOGY, 12 (2017)
DOI 10.1186/s13014-017-0781-4
Co-authors John Oconnor, Jarad Martin
2017 Fuangrod T, Greer PB, Simpson J, Zwan BJ, Middleton RH, 'A method for evaluating treatment quality using in vivo EPID dosimetry and statistical process control in radiation therapy', INTERNATIONAL JOURNAL OF HEALTH CARE QUALITY ASSURANCE, 30 90-102 (2017)
DOI 10.1108/IJHCQA-03-2016-0028
Co-authors Richard Middleton
2016 Zwan BJ, Barnes MP, Fuangrod T, Stanton CJ, O'Connor DJ, Keall PJ, Greer PB, 'An EPID-based system for gantry-resolved MLC quality assurance for VMAT', Journal of Applied Clinical Medical Physics, 17 348-365 (2016) [C1]

© Creative Commons Attribution 3.0 Unported License. Multileaf collimator (MLC) positions should be precisely and independently measured as a function of gantry angle as part of ... [more]

© Creative Commons Attribution 3.0 Unported License. Multileaf collimator (MLC) positions should be precisely and independently measured as a function of gantry angle as part of a comprehensive quality assurance (QA) program for volumetric-modulated arc therapy (VMAT). It is also ideal that such a QA program has the ability to relate MLC positional accuracy to patient-specific dosimetry in order to determine the clinical significance of any detected MLC errors. In this work we propose a method to verify individual MLC trajectories during VMAT deliveries for use as a routine linear accelerator QA tool. We also extend this method to reconstruct the 3D patient dose in the treatment planning system based on the measured MLC trajectories and the original DICOM plan file. The method relies on extracting MLC positions from EPID images acquired at 8.41fps during clinical VMAT deliveries. A gantry angle is automatically tagged to each image in order to obtain the MLC trajectories as a function of gantry angle. This analysis was performed for six clinical VMAT plans acquired at monthly intervals for three months. The measured trajectories for each delivery were compared to the MLC positions from the DICOM plan file. The maximum mean error detected was 0.07 mm and a maximum root-mean-square error was 0.8 mm for any leaf of any delivery. The sensitivity of this system was characterized by introducing random and systematic MLC errors into the test plans. It was demonstrated that the system is capable of detecting random and systematic errors on the range of 1-2mm and single leaf calibration errors of 0.5 mm. The methodology developed in the work has potential to be used for efficient routine linear accelerator MLC QA and pretreatment patient-specific QA and has the ability to relate measured MLC positional errors to 3D dosimetric errors within a patient volume.

DOI 10.1120/jacmp.v17i5.6312
Citations Scopus - 2
Co-authors John Oconnor
2016 Miri N, Keller P, Zwan BJ, Greer P, 'EPID-based dosimetry to verify IMRT planar dose distribution for the aS1200 EPID and FFF beams', Journal of Applied Clinical Medical Physics, 17 292-304 (2016) [C1]

We proposed to perform a basic dosimetry commissioning on a new imager system, the Varian aS1200 electronic portal imaging device (EPID) and TrueBeam 2.0 linear accelerator for fl... [more]

We proposed to perform a basic dosimetry commissioning on a new imager system, the Varian aS1200 electronic portal imaging device (EPID) and TrueBeam 2.0 linear accelerator for flattened (FF) and flattening filter-free (FFF) beams, then to develop an image-based quality assurance (QA) model for verification of the system delivery accuracy for intensity-modulated radiation therapy (IMRT) treatments. For dosimetry testing, linearity of dose response with MU, imager lag, and effectiveness of backscatter shielding were investigated. Then, an image-based model was developed to convert images to planar dose onto a virtual water phantom. The model parameters were identified using energy fluence of the Acuros treatment planning system (TPS) and, reference dose profiles and output factors measured at depths of 5, 10, 15, and 20 cm in water phantom for square fields. To validate the model, its calculated dose was compared to measured dose from MapCHECK 2 diode arrays for 36 IMRT fields at 10 cm depth delivered with 6X, 6XFFF, 10X, and 10XFFF energies. An in-house gamma function was used to compare planar doses pixel-by-pixel. Finally, the method was applied to the same IMRT fields to verify their pretreatment delivery dose compared with Eclipse TPS dose. For the EPID commissioning, dose linearity was within 0.4% above 5 MU and ~ 1% above 2 MU, measured lag was smaller than the previous EPIDs, and profile symmetry was improved. The model was validated with mean gamma pass rates (standard deviation) of 99.0% (0.4%), 99.5% (0.6%), 99.3% (0.4%), and 98.0% (0.8%) at 3%/3 mm for respectively 6X, 6XFFF, 10X, and 10XFFF beams. Using the same comparison criteria, the beam deliveries were verified with mean pass rates of 100% (0.0%), 99.6% (0.3%), 99.9% (0.1%), and 98.7% (1.4%). Improvements were observed in dosimetric response of the aS1200 imager compared to previous EPID models, and the model was successfully developed for the new system and delivery energies of 6 and 10 MV, FF, and FFF modes.

DOI 10.1120/jacmp.v17i6.6336
2016 Lee D, Greer PB, Pollock S, Kim T, Keall P, 'Quantifying the accuracy of the tumor motion and area as a function of acceleration factor for the simulation of the dynamic keyhole magnetic resonance imaging method', Medical Physics, 43 2639-2648 (2016) [C1]

© 2016 American Association of Physicists in Medicine. Purpose: The dynamic keyhole is a newMRimage reconstruction method for thoracic and abdominal MR imaging. To date, this met... [more]

© 2016 American Association of Physicists in Medicine. Purpose: The dynamic keyhole is a newMRimage reconstruction method for thoracic and abdominal MR imaging. To date, this method has not been investigated with cancer patient magnetic resonance imaging (MRI) data. The goal of this study was to assess the dynamic keyhole method for the task of lung tumor localization using cine-MR images reconstructed in the presence of respiratory motion. Methods: The dynamic keyhole method utilizes a previously acquired a library of peripheral k-space datasets at similar displacement and phase (where phase is simply used to determine whether the breathing is inhale to exhale or exhale to inhale) respiratory bins in conjunction with central k-space datasets (keyhole) acquired. External respiratory signals drive the process of sorting, matching, and combining the two k-space streams for each respiratory bin, thereby achieving faster image acquisition without substantial motion artifacts. This study was the first that investigates the impact of k-space undersampling on lung tumor motion and area assessment across clinically available techniques (zero-filling and conventional keyhole). In this study, the dynamic keyhole, conventional keyhole and zero-filling methods were compared to full k-space dataset acquisition by quantifying (1) the keyhole size required for central k-space datasets for constant image quality across sixty four cine-MRI datasets from nine lung cancer patients, (2) the intensity difference between the original and reconstructed images in a constant keyhole size, and (3) the accuracy of tumor motion and area directly measured by tumor autocontouring. Results: For constant image quality, the dynamic keyhole method, conventional keyhole, and zerofilling methods required 22%, 34%, and 49% of the keyhole size (P < 0.0001), respectively, compared to the full k-space image acquisition method. Compared to the conventional keyhole and zero-filling reconstructed images with the keyhole size utilized in the dynamic keyhole method, an average intensity difference of the dynamic keyhole reconstructed images (P < 0.0001) was minimal, and resulted in the accuracy of tumor motion within 99.6% (P < 0.0001) and the accuracy of tumor area within 98.0% (P < 0.0001) for lung tumor monitoring applications. Conclusions: This study demonstrates that the dynamic keyhole meth od is a promising technique for clinical applications such as image-guided radiation therapy requiring the MR monitoring of thoracic tumors. Based on the results from this study, the dynamic keyhole method could increase the imaging frequency by up to a factor of five compared with full k-space methods for real-time lung tumor MRI.

DOI 10.1118/1.4947508
Citations Scopus - 3Web of Science - 3
2016 Barnes MP, Greer PB, 'Time-resolved beam symmetry measurement for VMAT commissioning and quality assurance.', J Appl Clin Med Phys, 17 220-230 (2016)
DOI 10.1120/jacmp.v17i2.6026
2016 Miri N, Keller P, Zwan BJ, Greer P, 'EPID-based dosimetry to verify IMRT planar dose distribution for the aS1200 EPID and FFF beams.', J Appl Clin Med Phys, 17 292-304 (2016)
DOI 10.1120/jacmp.v17i6.6336
2016 Lee D, Greer PB, Ludbrook J, Arm J, Hunter P, Pollock S, et al., 'Audiovisual Biofeedback Improves Cine-Magnetic Resonance Imaging Measured Lung Tumor Motion Consistency', INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS, 94 628-636 (2016) [C1]
DOI 10.1016/j.ijrobp.2015.11.017
Citations Scopus - 4Web of Science - 3
2016 Zwan BJ, Barnes MP, Fuangrod T, Stanton CJ, O'Connor DJ, Keall PJ, Greer PB, 'An EPID-based system for gantry-resolved MLC quality assurance for VMAT', Journal of Applied Clinical Medical Physics, 17 348-365 (2016) [C1]

© Creative Commons Attribution 3.0 Unported License.Multileaf collimator (MLC) positions should be precisely and independently measured as a function of gantry angle as part of a... [more]

© Creative Commons Attribution 3.0 Unported License.Multileaf collimator (MLC) positions should be precisely and independently measured as a function of gantry angle as part of a comprehensive quality assurance (QA) program for volumetric-modulated arc therapy (VMAT). It is also ideal that such a QA program has the ability to relate MLC positional accuracy to patient-specific dosimetry in order to determine the clinical significance of any detected MLC errors. In this work we propose a method to verify individual MLC trajectories during VMAT deliveries for use as a routine linear accelerator QA tool. We also extend this method to reconstruct the 3D patient dose in the treatment planning system based on the measured MLC trajectories and the original DICOM plan file. The method relies on extracting MLC positions from EPID images acquired at 8.41fps during clinical VMAT deliveries. A gantry angle is automatically tagged to each image in order to obtain the MLC trajectories as a function of gantry angle. This analysis was performed for six clinical VMAT plans acquired at monthly intervals for three months. The measured trajectories for each delivery were compared to the MLC positions from the DICOM plan file. The maximum mean error detected was 0.07 mm and a maximum root-mean-square error was 0.8 mm for any leaf of any delivery. The sensitivity of this system was characterized by introducing random and systematic MLC errors into the test plans. It was demonstrated that the system is capable of detecting random and systematic errors on the range of 1-2mm and single leaf calibration errors of 0.5 mm. The methodology developed in the work has potential to be used for efficient routine linear accelerator MLC QA and pretreatment patient-specific QA and has the ability to relate measured MLC positional errors to 3D dosimetric errors within a patient volume.

DOI 10.1120/jacmp.v17i5.6312
Citations Scopus - 1
Co-authors John Oconnor
2016 Zwan BJ, Barnes MP, Fuangrod T, Stanton CJ, O'Connor DJ, Keall PJ, Greer PB, 'An EPID-based system for gantry-resolved MLC quality assurance for VMAT.', J Appl Clin Med Phys, 17 1-18 (2016)
DOI 10.1120/jacmp.v17i5.6312
Co-authors John Oconnor
2016 Lee D, Greer PB, Lapuz C, Ludbrook J, Hunter P, Arm J, et al., 'Audiovisual biofeedback guided breath-hold improves lung tumor position reproducibility and volume consistency', Advances in Radiation Oncology, (2016)

© 2017 The Authors on behalf of the American Society for Radiation Oncology. Purpose: Respiratory variation can increase the variability of tumor position and volume, accounting ... [more]

© 2017 The Authors on behalf of the American Society for Radiation Oncology. Purpose: Respiratory variation can increase the variability of tumor position and volume, accounting for larger treatment margins and longer treatment times. Audiovisual biofeedback as a breath-hold technique could be used to improve the reproducibility of lung tumor positions at inhalation and exhalation for the radiation therapy of mobile lung tumors. This study aimed to assess the impact of audiovisual biofeedback breath-hold (AVBH) on interfraction lung tumor position reproducibility and volume consistency for respiratory-gated lung cancer radiation therapy. Methods: Lung tumor position and volume were investigated in 9 patients with lung cancer who underwent a breath-hold training session with AVBH before 2 magnetic resonance imaging (MRI) sessions. During the first MRI session (before treatment), inhalation and exhalation breath-hold 3-dimensional MRI scans with conventional breath-hold (CBH) using audio instructions alone and AVBH were acquired. The second MRI session (midtreatment) was repeated within 6 weeks after the first session. Gross tumor volumes (GTVs) were contoured on each dataset. CBH and AVBH were compared in terms of tumor position reproducibility as assessed by GTV centroid position and position range (defined as the distance of GTV centroid position between inhalation and exhalation) and tumor volume consistency as assessed by GTV between inhalation and exhalation. Results: Compared with CBH, AVBH improved the reproducibility of interfraction GTV centroid position by 46% (P = .009) from 8.8 mm to 4.8 mm and GTV position range by 69% (P = .052) from 7.4 mm to 2.3 mm. Compared with CBH, AVBH also improved the consistency of intrafraction GTVs by 70% (P = .023) from 7.8 cm 3 to 2.5 cm 3 . Conclusions: This study demonstrated that audiovisual biofeedback can be used to improve the reproducibility and consistency of breath-hold lung tumor position and volume, respectively. These results may provide a pathway to achieve more accurate lung cancer radiation treatment in addition to improving various medical imaging and treatments by using breath-hold procedures.

DOI 10.1016/j.adro.2017.03.002
2016 Fuangrod T, Greer PB, Woodruff HC, Simpson J, Bhatia S, Zwan B, et al., 'Investigation of a real-time EPID-based patient dose monitoring safety system using site-specific control limits', RADIATION ONCOLOGY, 11 (2016) [C1]
DOI 10.1186/s13014-016-0682-y
Co-authors Richard Middleton
2016 Seregni M, Paganelli C, Lee D, Greer PB, Baroni G, Keall PJ, Riboldi M, 'Motion prediction in MRI-guided radiotherapy based on interleaved orthogonal cine-MRI', Physics in Medicine and Biology, 61 872-887 (2016) [C1]

© 2016 Institute of Physics and Engineering in Medicine. In-room cine-MRI guidance can provide non-invasive target localization during radiotherapy treatment. However, in order t... [more]

© 2016 Institute of Physics and Engineering in Medicine. In-room cine-MRI guidance can provide non-invasive target localization during radiotherapy treatment. However, in order to cope with finite imaging frequency and system latencies between target localization and dose delivery, tumour motion prediction is required. This work proposes a framework for motion prediction dedicated to cine-MRI guidance, aiming at quantifying the geometric uncertainties introduced by this process for both tumour tracking and beam gating. The tumour position, identified through scale invariant features detected in cine-MRI slices, is estimated at high-frequency (25 Hz) using three independent predictors, one for each anatomical coordinate. Linear extrapolation, auto-regressive and support vector machine algorithms are compared against systems that use no prediction or surrogate-based motion estimation. Geometric uncertainties are reported as a function of image acquisition period and system latency. Average results show that the tracking error RMS can be decreased down to a [0.2; 1.2] mm range, for acquisition periods between 250 and 750 ms and system latencies between 50 and 300 ms. Except for the linear extrapolator, tracking and gating prediction errors were, on average, lower than those measured for surrogate-based motion estimation. This finding suggests that cine-MRI guidance, combined with appropriate prediction algorithms, could relevantly decrease geometric uncertainties in motion compensated treatments.

DOI 10.1088/0031-9155/61/2/872
Citations Scopus - 5Web of Science - 6
2016 Chandra SS, Dowling JA, Greer PB, Martin J, Wratten C, Pichler P, et al., 'Fast automated segmentation of multiple objects via spatially weighted shape learning', Physics in Medicine and Biology, 61 8070-8084 (2016) [C1]

© 2016 Institute of Physics and Engineering in Medicine. Active shape models (ASMs) have proved successful in automatic segmentation by using shape and appearance priors in a num... [more]

© 2016 Institute of Physics and Engineering in Medicine. Active shape models (ASMs) have proved successful in automatic segmentation by using shape and appearance priors in a number of areas such as prostate segmentation, where accurate contouring is important in treatment planning for prostate cancer. The ASM approach however, is heavily reliant on a good initialisation for achieving high segmentation quality. This initialisation often requires algorithms with high computational complexity, such as three dimensional (3D) image registration. In this work, we present a fast, self-initialised ASM approach that simultaneously fits multiple objects hierarchically controlled by spatially weighted shape learning. Prominent objects are targeted initially and spatial weights are progressively adjusted so that the next (more difficult, less visible) object is simultaneously initialised using a series of weighted shape models. The scheme was validated and compared to a multi-atlas approach on 3D magnetic resonance (MR) ima ges of 38 cancer patients and had the same (mean, median, inter-rater) Dice's similarity coefficients of (0.79, 0.81, 0.85), while having no registration error and a computational time of 12-15 min, nearly an order of magnitude faster than the multi-atlas approach.

DOI 10.1088/0031-9155/61/22/8070
Co-authors Jarad Martin
2016 Barnes MP, Rowshanfarzad P, Greer PB, 'VMAT linear accelerator commissioning and quality assurance: Dose control and gantry speed tests', Journal of Applied Clinical Medical Physics, 17 246-261 (2016) [C1]

© Creative Commons Attribution 4.0 International License. In VMAT treatment delivery the ability of the linear accelerator (linac) to accurately control dose versus gantry angle ... [more]

© Creative Commons Attribution 4.0 International License. In VMAT treatment delivery the ability of the linear accelerator (linac) to accurately control dose versus gantry angle is critical to delivering the plan correctly. A new VMAT test delivery was developed to specifically test the dose versus gantry angle with the full range of allowed gantry speeds and dose rates. The gantry-mounted IBA MatriXX with attached inclinometer was used in movie mode to measure the instantaneous relative dose versus gantry angle during the plan every 0.54 s. The results were compared to the expected relative dose at each gantry angle calculated from the plan. The same dataset was also used to compare the instantaneous gantry speeds throughout the delivery compared to the expected gantry speeds from the plan. Measurements performed across four linacs generally show agreement between measurement and plan to within 1.5% in the constant dose rate regions and dose rate modulation within 0.1 s of the plan. Instantaneous gantry speed was measured to be within 0.11°/s of the plan (1 SD). An error in one linac was detected in that the nominal gantry speed was incorrectly calibrated. This test provides a practical method to quality-assure critical aspects of VMAT delivery including dose versus gantry angle and gantry speed control. The method can be performed with any detector that can acquire time-resolved dosimetric information that can be synchronized with a measurement of gantry angle. The test fulfils several of the aims of the recent Netherlands Commission on Radiation Dosimetry (NCS) Report 24, which provides recommendations for comprehensive VMAT quality assurance.

Citations Scopus - 1Web of Science - 1
2016 Barnes MP, Greer PB, 'Time-resolved beam symmetry measurement for VMAT commissioning and quality assurance', Journal of applied clinical medical physics, 17 6026 (2016) [C1]

In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method... [more]

In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method of measuring time-resolved beam symmetry measurement during a VMAT delivery that includes extreme variations of dose rate and gantry speed. The Sun Nuclear IC Profiler in gantry mount was used to measure time-resolved in-plane and cross-plane profiles during plan delivery from which symmetry could be determined. Time-resolved symmetry measurements were performed throughout static field exposures at cardinal gantry angles, conformal arcs with constant dose rate and gantry speed, and during a VMAT test plan with gantry speed and dose rate modulation. Measurements were performed for both clockwise and counterclockwise gantry rotation and across four Varian 21iX lin-acs. The symmetry was found to be generally constant throughout the static field exposures to within 0.3% with an exception on one linac of up to 0.7%. Agreement in symmetry between cardinal angles was always within 1.0% and typically within 0.6%. During conformal arcs the results for clockwise and counterclockwise rotation were in agreement to within 0.3%. Both clockwise and counterclockwise tended to vary in similar manner by up to 0.5% during arc consistent with the cardinal gantry angle static field results. During the VMAT test plan the symmetry generally was in agreement with the conformal arc results. Greater variation in symmetry was observed in the low-dose-rate regions by up to 1.75%. All results were within clinically acceptable levels using the tolerances of NCS Report 24 (2015).

Citations Scopus - 1Web of Science - 1
2016 Zwan BJ, Barnes MP, Fuangrod T, Stanton CJ, O'Connor DJ, Keall PJ, Greer PB, 'An EPID-based system for gantry-resolved MLC quality assurance for VMAT.', J Appl Clin Med Phys, 17 1-18 (2016) [C1]
DOI 10.1120/jacmp.v17i5.6312
Co-authors John Oconnor
2016 Loh J, Baker K, Sridharan S, Greer P, Wratten C, Capp A, et al., 'Re: Infections after Fiducial Marker Implantation for Prostate Radiotherapy: Are we Underestimating the Risks?', JOURNAL OF UROLOGY, 196 443-443 (2016)
2016 Kron T, Lehmann J, Greer PB, 'Dosimetry of ionising radiation in modern radiation oncology', PHYSICS IN MEDICINE AND BIOLOGY, 61 R167-R205 (2016) [C1]
DOI 10.1088/0031-9155/61/14/R167
Citations Scopus - 5Web of Science - 4
2016 Barnes MP, Greer PB, 'Time-resolved beam symmetry measurement for VMAT commissioning and quality assurance', Journal of applied clinical medical physics, 17 6026 (2016)

In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method... [more]

In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method of measuring time-resolved beam symmetry measurement during a VMAT delivery that includes extreme variations of dose rate and gantry speed. The Sun Nuclear IC Profiler in gantry mount was used to measure time-resolved in-plane and cross-plane profiles during plan delivery from which symmetry could be determined. Time-resolved symmetry measurements were performed throughout static field exposures at cardinal gantry angles, conformal arcs with constant dose rate and gantry speed, and during a VMAT test plan with gantry speed and dose rate modulation. Measurements were performed for both clockwise and counterclockwise gantry rotation and across four Varian 21iX lin-acs. The symmetry was found to be generally constant throughout the static field exposures to within 0.3% with an exception on one linac of up to 0.7%. Agreement in symmetry between cardinal angles was always within 1.0% and typically within 0.6%. During conformal arcs the results for clockwise and counterclockwise rotation were in agreement to within 0.3%. Both clockwise and counterclockwise tended to vary in similar manner by up to 0.5% during arc consistent with the cardinal gantry angle static field results. During the VMAT test plan the symmetry generally was in agreement with the conformal arc results. Greater variation in symmetry was observed in the low-dose-rate regions by up to 1.75%. All results were within clinically acceptable levels using the tolerances of NCS Report 24 (2015).

2016 Ghose S, Mitra J, Rivest-Hénault D, Fazlollahi A, Stanwell P, Pichler P, et al., 'MRI-alone radiation therapy planning for prostate cancer: Automatic fiducial marker detection', Medical Physics, 43 2218-2228 (2016) [C1]

© 2016 American Association of Physicists in Medicine. Purpose: The feasibility of radiation therapy treatment planning using substitute computed tomography (sCT) generated from ... [more]

© 2016 American Association of Physicists in Medicine. Purpose: The feasibility of radiation therapy treatment planning using substitute computed tomography (sCT) generated from magnetic resonance images (MRIs) has been demonstrated by a number of research groups. One challenge with an MRI-alone workflow is the accurate identification of intraprostatic gold fiducial markers, which are frequently used for prostate localization prior to each dose delivery fraction. This paper investigates a template-matching approach for the detection of these seeds in MRI. Methods: Two different gradient echo T1 and T2* weighted MRI sequences were acquired from fifteen prostate cancer patients and evaluated for seed detection. For training, seed templates from manual contours were selected in a spectral clustering manifold learning framework. This aids in clustering "similar" gold fiducial markers together. The marker with the minimum distance to a cluster centroid was selected as the representative template of that cluster during training. During testing, Gaussian mixture modeling followed by a Markovian model was used in automatic detection of the probable candidates. The probable candidates were rigidly registered to the templates identified from spectral clustering, and a similarity metric is computed for ranking and detection. Results: A fiducial detection accuracy of 95% was obtained compared to manual observations. Expert radiation therapist observers were able to correctly identify all three implanted seeds on 11 of the 15 scans (the proposed method correctly identified all seeds on 10 of the 15). Conclusions: An novel automatic framework for gold fiducial marker detection in MRI is proposed and evaluated with detection accuracies comparable to manual detection. When radiation therapists are unable to determine the seed location in MRI, they refer back to the planning CT (only available in the existing clinical framework); similarly, an automatic quality control is built into the automatic software to ensure that all gold seeds are either correctly detected or a warning is raised for further manual intervention.

DOI 10.1118/1.4944871
Co-authors Peter Stanwell
2015 Loh J, Baker K, Sridharan S, Greer P, Wratten C, Capp A, et al., 'Infections after fiducial marker implantation for prostate radiotherapy: are we underestimating the risks?', RADIATION ONCOLOGY, 10 (2015) [C1]
DOI 10.1186/s13014-015-0347-2
Citations Scopus - 8Web of Science - 5
Co-authors Jarad Martin
2015 Van Uytven E, Van Beek T, McCowan PM, Chytyk-Praznik K, Greer PB, McCurdy BMC, 'Validation of a method for in vivo 3D dose reconstruction for IMRT and VMAT treatments using on-treatment EPID images and a model-based forward-calculation algorithm', Medical Physics, 42 6945-6954 (2015) [C1]

© 2015 American Association of Physicists in Medicine. Purpose: Radiation treatments are trending toward delivering higher doses per fraction under stereotactic radiosurgery and ... [more]

© 2015 American Association of Physicists in Medicine. Purpose: Radiation treatments are trending toward delivering higher doses per fraction under stereotactic radiosurgery and hypofractionated treatment regimens. There is a need for accurate 3D in vivo patient dose verification using electronic portal imaging device (EPID) measurements. This work presents a model-based technique to compute full three-dimensional patient dose reconstructed from on-treatment EPID portal images (i.e., transmission images). Methods: EPID dose is converted to incident fluence entering the patient using a series of steps which include converting measured EPID dose to fluence at the detector plane and then back-projecting the primary source component of the EPID fluence upstream of the patient. Incident fluence is then recombined with predicted extra-focal fluence and used to calculate 3D patient dose via a collapsed-cone convolution method. This method is implemented in an iterative manner, although in practice it provides accurate results in a single iteration. The robustness of the dose reconstruction technique is demonstrated with several simple slab phantom and nine anthropomorphic phantom cases. Prostate, head and neck, and lung treatments are all included as well as a range of delivery techniques including VMAT and dynamic intensity modulated radiation therapy (IMRT). Results: Results indicate that the patient dose reconstruction algorithm compares well with treatment planning system computed doses for controlled test situations. For simple phantom and square field tests, agreement was excellent with a 2%/2 mm 3D chi pass rate .98.9%. On anthropomorphic phantoms, the 2%/2 mm 3D chi pass rates ranged from 79.9% to 99.9% in the planning target volume (PTV) region and 96.5% to 100% in the low dose region ( > 20% of prescription, excluding PTV and skin build-up region). Conclusions: An algorithm to reconstruct delivered patient 3D doses from EPID exit dosimetry measurements was presented. The method was applied to phantom and patient data sets, as well as for dynamic IMRT and VMAT delivery techniques. Results indicate that the EPID dose reconstruction algorithm presented in this work is suitable for clinical implementation.

DOI 10.1118/1.4935199
Citations Scopus - 12Web of Science - 9
2015 Herschtal A, te Marvelde L, Mengersen K, Hosseinifard Z, Foroudi F, Devereux T, et al., 'Calculating radiotherapy margins based on Bayesian modelling of patient specific random errors', PHYSICS IN MEDICINE AND BIOLOGY, 60 1793-1805 (2015) [C1]
DOI 10.1088/0031-9155/60/5/1793
2015 Dowling JA, Sun J, Pichler P, Rivest-Hénault D, Ghose S, Richardson H, et al., 'Automatic substitute computed tomography generation and contouring for magnetic resonance imaging (MRI)-alone external beam radiation therapy from standard MRI sequences', International Journal of Radiation Oncology Biology Physics, 93 1144-1153 (2015) [C1]

Crown Copyright © 2015 Published by Elsevier Inc. All rights reserved. Purpose To validate automatic substitute computed tomography CT (sCT) scans generated from standard T2-weig... [more]

Crown Copyright © 2015 Published by Elsevier Inc. All rights reserved. Purpose To validate automatic substitute computed tomography CT (sCT) scans generated from standard T2-weighted (T2w) magnetic resonance (MR) pelvic scans for MR-Sim prostate treatment planning. Patients and Methods A Siemens Skyra 3T MR imaging (MRI) scanner with laser bridge, flat couch, and pelvic coil mounts was used to scan 39 patients scheduled for external beam radiation therapy for localized prostate cancer. For sCT generation a whole-pelvis MRI scan (1.6 mm 3-dimensional isotropic T2w SPACE [Sampling Perfection with Application optimized Contrasts using different flip angle Evolution] sequence) was acquired. Three additional small field of view scans were acquired: T2w, T2*w, and T1w flip angle 80° for gold fiducials. Patients received a routine planning CT scan. Manual contouring of the prostate, rectum, bladder, and bones was performed independently on the CT and MR scans. Three experienced observers contoured each organ on MRI, allowing interobserver quantification. To generate a training database, each patient CT scan was coregistered to their whole-pelvis T2w using symmetric rigid registration and structure-guided deformable registration. A new multi-atlas local weighted voting method was used to generate automatic contours and sCT results. Results The mean error in Hounsfield units between the sCT and corresponding patient CT (within the body contour) was 0.6 ± 14.7 (mean ± 1 SD), with a mean absolute error of 40.5 ± 8.2 Hounsfield units. Automatic contouring results were very close to the expert interobserver level (Dice similarity coefficient): prostate 0.80 ± 0.08, bladder 0.86 ± 0.12, rectum 0.84 ± 0.06, bones 0.91 ± 0.03, and body 1.00 ± 0.003. The change in monitor units between the sCT-based plans relative to the gold standard CT plan for the same dose prescription was found to be 0.3% ± 0.8%. The 3-dimensional ¿ pass rate was 1.00 ± 0.00 (2 mm/2%). Conclusions The MR-Sim setup and automatic sCT generation methods using standard MR sequences generates realistic contours and electron densities for prostate cancer radiation therapy dose planning and digitally reconstructed radiograph generation.

DOI 10.1016/j.ijrobp.2015.08.045
Citations Scopus - 17Web of Science - 15
Co-authors Fred Menk, Jarad Martin
2015 Paganelli C, Lee D, Greer PB, Baroni G, Riboldi M, Keall P, 'Quantification of lung tumor rotation with automated landmark extraction using orthogonal cine MRI images', Physics in Medicine and Biology, 60 7165-7178 (2015) [C1]

© 2015 Institute of Physics and Engineering in Medicine. The quantification of tumor motion in sites affected by respiratory motion is of primary importance to improve treatment ... [more]

© 2015 Institute of Physics and Engineering in Medicine. The quantification of tumor motion in sites affected by respiratory motion is of primary importance to improve treatment accuracy. To account for motion, different studies analyzed the translational component only, without focusing on the rotational component, which was quantified in a few studies on the prostate with implanted markers. The aim of our study was to propose a tool able to quantify lung tumor rotation without the use of internal markers, thus providing accurate motion detection close to critical structures such as the heart or liver. Specifically, we propose the use of an automatic feature extraction method in combination with the acquisition of fast orthogonal cine MRI images of nine lung patients. As a preliminary test, we evaluated the performance of the feature extraction method by applying it on regions of interest around (i) the diaphragm and (ii) the tumor and comparing the estimated motion with that obtained by (i) the extraction of the diaphragm profile and (ii) the segmentation of the tumor, respectively. The results confirmed the capability of the proposed method in quantifying tumor motion. Then, a point-based rigid registration was applied to the extracted tumor features between all frames to account for rotation. The median lung rotation values were -0.6 ± 2.3° and -1.5 ± 2.7° in the sagittal and coronal planes respectively, confirming the need to account for tumor rotation along with translation to improve radiotherapy treatment.

DOI 10.1088/0031-9155/60/18/7165
Citations Scopus - 1Web of Science - 1
2015 Rivest-Hénault D, Dowson N, Greer PB, Fripp J, Dowling JA, 'Robust inverse-consistent affine CT-MR registration in MRI-assisted and MRI-alone prostate radiation therapy', Medical Image Analysis, 23 56-69 (2015) [C1]

© 2015. Background: CT-MR registration is a critical component of many radiation oncology protocols. In prostate external beam radiation therapy, it allows the propagation of MR-... [more]

© 2015. Background: CT-MR registration is a critical component of many radiation oncology protocols. In prostate external beam radiation therapy, it allows the propagation of MR-derived contours to reference CT images at the planning stage, and it enables dose mapping during dosimetry studies. The use of carefully registered CT-MR atlases allows the estimation of patient specific electron density maps from MRI scans, enabling MRI-alone radiation therapy planning and treatment adaptation. In all cases, the precision and accuracy achieved by registration influences the quality of the entire process.Problem: Most current registration algorithms do not robustly generalize and lack inverse-consistency, increasing the risk of human error and acting as a source of bias in studies where information is propagated in a particular direction, e.g. CT to MR or vice versa. In MRI-based treatment planning where both CT and MR scans serve as spatial references, inverse-consistency is critical, if under-acknowledged.Purpose: A robust, inverse-consistent, rigid/affine registration algorithm that is well suited to CT-MR alignment in prostate radiation therapy is p resented.Method: The presented method is based on a robust block-matching optimization process that utilises a half-way space definition to maintain inverse-consistency. Inverse-consistency substantially reduces the influence of the order of input images, simplifying analysis, and increasing robustness. An open source implementation is available online at http://aehrc.github.io/Mirorr/.Results: Experimental results on a challenging 35 CT-MR pelvis dataset demonstrate that the proposed method is more accurate than other popular registration packages and is at least as accurate as the state of the art, while being more robust and having an order of magnitude higher inverse-consistency than competing approaches.Conclusion: The presented results demonstrate that the proposed registration algorithm is readily applicable to prostate radiation therapy planning.

DOI 10.1016/j.media.2015.04.014
Citations Scopus - 13Web of Science - 9
2015 Sun J, Dowling JA, Pichler P, Parker J, Martin J, Stanwell P, et al., 'Investigation on the performance of dedicated radiotherapy positioning devices for MR scanning for prostate planning', Journal of Applied Clinical Medical Physics, 16 4-13 (2015) [C1]

The purpose of this study was to investigate performance of the couch and coil mounts designed for MR-simulation prostate scanning using data from ten volunteers. Volunteers were ... [more]

The purpose of this study was to investigate performance of the couch and coil mounts designed for MR-simulation prostate scanning using data from ten volunteers. Volunteers were scanned using the standard MR scanning protocol with the MR coil directly strapped on the external body and the volunteer lying on the original scanner table. They also were scanned using a MR-simulation table top and pelvic coil mounts. MR images from both setups were compared in terms of body contour variation and image quality effects within particular organs of interest. Six-field conformal plans were generated on the two images with assigned bulk density for dose calculation. With the MR-simulation devices, the anterior skin deformation was reduced by up to 1.7 cm. The hard tabletop minimizes the posterior body deformation which can be up to 2.3 cm on the standard table, depending on the weight of volunteer. The image signal-to-noise ratio reduced by 14% and 25% on large field of view (FOV) and small FOV images, respectively, after using the coil mount; the prostate volume contoured on two images showed difference of 1.05 ± 0.66 cm3. The external body deformation caused a mean dose reduction of 0.6 ± 0.3 Gy, while the coverage reduced by 22% ± 13% and 27% ± 6% in V98 and V100, respectively. A dedicated MR simulation setup for prostate radiotherapy is essential to ensure the agreement between planning anatomy and treatment anatomy. The image signal was reduced after applying the coil mount, but no significant effect was found on prostate contouring.

DOI 10.1120/jacmp.v16i2.4848
Citations Scopus - 1
Co-authors Peter Stanwell, Fred Menk, Jarad Martin
2015 Sun J, Dowling J, Pichler P, Menk F, Rivest-Henault D, Lambert J, et al., 'MRI simulation: End-to-end testing for prostate radiation therapy using geometric pelvic MRI phantoms', Physics in Medicine and Biology, 60 3097-3109 (2015) [C1]

© 2015 Institute of Physics and Engineering in Medicine. To clinically implement MRI simulation or MRI-alone treatment planning requires comprehensive end-to-end testing to ensur... [more]

© 2015 Institute of Physics and Engineering in Medicine. To clinically implement MRI simulation or MRI-alone treatment planning requires comprehensive end-to-end testing to ensure an accurate process. The purpose of this study was to design and build a geometric phantom simulating a human male pelvis that is suitable for both CT and MRI scanning and use it to test geometric and dosimetric aspects of MRI simulation including treatment planning and digitally reconstructed radiograph (DRR) generation. A liquid filled pelvic shaped phantom with simulated pelvic organs was scanned in a 3T MRI simulator with dedicated radiotherapy couch-top, laser bridge and pelvic coil mounts. A second phantom with the same external shape but with an internal distortion grid was used to quantify the distortion of the MR image. Both phantoms were also CT scanned as the gold-standard for both geometry and dosimetry. Deformable image registration was used to quantify the MR distortion. Dose comparison was made using a seven-field IMRT plan developed on the CT scan with the fluences copied to the MR image and recalculated using bulk electron densities. Without correction the maximum distortion of the MR compared with the CT scan was 7.5 mm across the pelvis, while this was reduced to 2.6 and 1.7 mm by the vendor's 2D and 3D correction algorithms, respectively. Within the locations of the internal organs of interest, the distortion was < 1.5 and < 1 mm with 2D and 3D correction algorithms, respectively. The dose at the prostate isocentre calculated on CT and MRI images differed by 0.01% (1.1 cGy). Positioning shifts were within 1 mm when setup was performed using MRI generated DRRs compared to setup using CT DRRs. The MRI pelvic phantom allows end-to-end testing of the MRI simulation workflow with comparison to the gold-standard CT based process. MRI simulation was found to be geometrically accurate with organ dimensions, dose distributions and DRR based setup within acceptable limits compared to CT.

DOI 10.1088/0031-9155/60/8/3097
Citations Scopus - 7Web of Science - 6
Co-authors Jim Denham, Jarad Martin, Fred Menk
2015 Whelan B, Kumar S, Dowling J, Begg J, Lambert J, Lim K, et al., 'Utilising pseudo-CT data for dose calculation and plan optimization in adaptive radiotherapy', Australasian Physical and Engineering Sciences in Medicine, (2015) [C1]

© 2015 Australasian College of Physical Scientists and Engineers in Medicine To quantify the dose calculation error and resulting optimization uncertainty caused by performing in... [more]

© 2015 Australasian College of Physical Scientists and Engineers in Medicine To quantify the dose calculation error and resulting optimization uncertainty caused by performing inverse treatment planning on inaccurate electron density data (pseudo-CT) as needed for adaptive radiotherapy and Magnetic Resonance Imaging (MRI) based treatment planning. Planning Computer Tomography (CT) data from 10 cervix cancer patients was used to generate 4 pseudo-CT data sets. Each pseudo-CT was created based on an available method of assigning electron density to an anatomic image. An inversely modulated radiotherapy (IMRT) plan was developed on each planning CT. The dose calculation error caused by each pseudo-CT data set was quantified by comparing the dose calculated each pseudo-CT data set with that calculated on the original planning CT for the same IMRT plan. The optimization uncertainty introduced by the dose calculation error was quantified by re-optimizing the same optimization parameters on each pseudo-CT data set and comparing against the original planning CT. Dose differences were quantified by assessing the Equivalent Uniform Dose (EUD) for targets and relevant organs at risk. Across all pseudo-CT data sets and all organs, the absolute mean dose calculation error was 0.2 Gy, and was within 2 % of the prescription dose in 98.5 % of cases. Then absolute mean optimisation error was 0.3 Gy EUD, indicating that that inverse optimisation is impacted by the dose calculation error. However, the additional uncertainty introduced to plan optimisation is small compared the sources of variation which already exist. Use of inaccurate electron density data for inverse treatment planning results in a dose calculation error, which in turn introduces additional uncertainty into the plan optimization process. In this study, we showed that both of these effects are clinically acceptable for cervix cancer patients using four different pseudo-CT data sets. Dose calculation and inverse optimization on pseudo-CT is feasible for this patient cohort.

DOI 10.1007/s13246-015-0376-z
Citations Scopus - 1Web of Science - 1
2015 Fuangrod T, Rowshanfarzad P, Greer PB, Middleton RH, 'A cine-EPID based method for jaw detection and quality assurance for tracking jaw in IMRT/VMAT treatments', Physica Medica, 31 16-24 (2015) [C1]

© 2014 Associazione Italiana di Fisica Medica. A new tool with the potential to verify and track jaw position during delivery has been developed. The method should be suitable fo... [more]

© 2014 Associazione Italiana di Fisica Medica. A new tool with the potential to verify and track jaw position during delivery has been developed. The method should be suitable for independent quality assurance for jaw position during jaw tracking dynamic IMRT and VMAT treatments. The jaw detection and tracking algorithm developed consists of five main steps. Firstly, the image is enhanced by removing a normalised predicted EPID image (that does not include the collimator transmission) from each cine EPID image. Then, using a histogram clustering technique a global intensity threshold level was determined. This threshold level was used to classify each pixel of the image as either under the jaws or under the MLC. Additionally, the collimator angle was automatically detected and used to rotate the image to vertical direction. Finally, this rotation allows the jaw positions to be determined using vertical and horizontal projection profiles. Nine IMRT fields (with static jaws) and a single VMAT clinical field (with dynamic jaws) were tested by determining the root mean square difference between planned and detected jaw positions. The test results give a detection accuracy of ±1mm RMS error for static jaw IMRT treatments and ±1.5mm RMS error for the dynamic jaw VMAT treatment. This method is designed for quality assurance and verification in modern radiation therapy; to detect the position of static jaws or verify the position of tracking jaws in more complex treatments. This method uses only information extracted from EPID images and it is therefore independent from the linear accelerator.

DOI 10.1016/j.ejmp.2014.11.002
Citations Scopus - 7Web of Science - 8
Co-authors Richard Middleton
2015 Sun J, Barnes M, Dowling J, Menk F, Stanwell P, Greer PB, 'An open source automatic quality assurance (OSAQA) tool for the ACR MRI phantom.', Australas Phys Eng Sci Med, 38 39-46 (2015) [C1]
DOI 10.1007/s13246-014-0311-8
Citations Scopus - 2Web of Science - 3
Co-authors Fred Menk, Peter Stanwell
2015 Woodruff HC, Fuangrod T, Van Uytven E, McCurdy BMC, Van Beek T, Bhatia S, Greer PB, 'First Experience with Real-Time EPID-Based Delivery Verification during IMRT and VMAT Sessions', International Journal of Radiation Oncology Biology Physics, 93 516-522 (2015) [C1]

© 2015 Elsevier Inc. All rights reserved. Purpose Gantry-mounted megavoltage electronic portal imaging devices (EPIDs) have become ubiquitous on linear accelerators. WatchDog is ... [more]

© 2015 Elsevier Inc. All rights reserved. Purpose Gantry-mounted megavoltage electronic portal imaging devices (EPIDs) have become ubiquitous on linear accelerators. WatchDog is a novel application of EPIDs, in which the image frames acquired during treatment are used to monitor treatment delivery in real time. We report on the preliminary use of WatchDog in a prospective study of cancer patients undergoing intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) and identify the challenges of clinical adoption. Methods and Materials At the time of submission, 28 cancer patients (head and neck, pelvis, and prostate) undergoing fractionated external beam radiation therapy (24 IMRT, 4 VMAT) had =1 treatment fraction verified in real time (131 fractions or 881 fields). EPID images acquired continuously during treatment were synchronized and compared with model-generated transit EPID images within a frame time (~0.1 s). A ¿ comparison was performed to cumulative frames to gauge the overall delivery quality, and the resulting pass rates were reported graphically during treatment delivery. Every frame acquired (500-1500 per fraction) was saved for postprocessing and analysis. Results The system reported the mean ± standard deviation in real time ¿ 91.1% ± 11.5% (83.6% ± 13.2%) for cumulative frame ¿ analysis with 4%, 4 mm (3%, 3 mm) criteria, global over the integrated image. Conclusions A real-time EPID-based radiation delivery verification system for IMRT and VMAT has been demonstrated that aims to prevent major mistreatments in radiation therapy.

DOI 10.1016/j.ijrobp.2015.07.2271
Citations Scopus - 8Web of Science - 9
2014 Sun J, Pichler P, Dowling J, Menk F, Stanwell P, Arm J, Greer PB, 'MR simulation for prostate radiation therapy: Effect of coil mounting position on image quality', British Journal of Radiology, 87 (2014) [C1]

© 2014 The Authors. Methods: A custom-designed pelvic-shaped phantom was scanned by systematically increasing the anterior body-tocoil (BTC) distance from 30 to 90mm. The image q... [more]

© 2014 The Authors. Methods: A custom-designed pelvic-shaped phantom was scanned by systematically increasing the anterior body-tocoil (BTC) distance from 30 to 90mm. The image quality near the organs of interest was determined in order to characterize the relationship between image quality and BTC distance at the critical organ structures. The half intensity reduction (HIR) was calculated to determine the sensitivity of each organ structure to the BTC distance change. Advances in knowledge: A method to characterize the effect on image quality due to the use of coil mounts was demonstrated. Coil mounts whose height can be adjusted individually to keep BTC distance constant are necessary to maintain a uniform image across the entire field of view. Results: As the BTC distance increased, the uniformity reduced at 3% per millimetre. The HIR value indicated that the bladder signal is most sensitive to the change in BTC distance. By maintaining a constant BTC distance set-up, the intensity uniformitywas improved by 28% along the B0 directions. Conclusion: Positioning the MRI coil on mounts can reduce body deformation but adversely degrades the image quality. The magnitude of this effect has been quantified for prostate MR simulation scanning. The coil needs to be positioned not only with a minimal but also uniform BTC distance in order to maximize image quality. Objective: To eliminate the effects of body deformation for MR-based prostate treatment planning, coil mounts are essential. In this study, we evaluated the effect of the coil set-up on image quality.

DOI 10.1259/bjr.20140325
Citations Scopus - 3Web of Science - 2
Co-authors Fred Menk, Peter Stanwell
2014 Fuangrod T, Woodruff HC, Rowshanfarzad P, O'Connor DJ, Middleton RH, Greer PB, 'An independent system for real-time dynamic multileaf collimation trajectory verification using EPID', PHYSICS IN MEDICINE AND BIOLOGY, 59 61-81 (2014) [C1]
DOI 10.1088/0031-9155/59/1/61
Citations Scopus - 7Web of Science - 7
Co-authors John Oconnor, Richard Middleton
2014 Zwan BJ, King BW, O'Connor DJ, Greer PB, 'Dose-to-water conversion for the backscatter-shielded EPID: a frame-based method to correct for EPID energy response to MLC transmitted radiation.', Med Phys, 41 081716 (2014) [C1]
DOI 10.1118/1.4890677
Citations Scopus - 1Web of Science - 1
Co-authors John Oconnor
2014 Sabet M, Rowshanfarzad P, Menk FW, Greer PB, 'Transit dosimetry in dynamic IMRT with an a-Si EPID', MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING, 52 579-588 (2014) [C1]
DOI 10.1007/s11517-014-1161-y
Citations Scopus - 3Web of Science - 3
Co-authors Fred Menk
2014 Rivest-Hénault D, Dowson N, Greer P, Dowling J, 'Inverse-consistent rigid registration of CT and MR for MR-based planning and adaptive prostate radiation therapy', Journal of Physics: Conference Series, 489 (2014)

MRI-alone treatment planning and adaptive MRI-based prostate radiation therapy are two promising techniques that could significantly increase the accuracy of the curative dose del... [more]

MRI-alone treatment planning and adaptive MRI-based prostate radiation therapy are two promising techniques that could significantly increase the accuracy of the curative dose delivery processes while reducing the total radiation dose. State-of-the-art methods rely on the registration of a patient MRI with a MR-CT atlas for the estimation of pseudo-CT [5]. This atlas itself is generally created by registering many CT and MRI pairs. Most registration methods are not symmetric, but the order of the images influences the result [8] . The computed transformation is therefore biased, introducing unwanted variability. This work examines how much a symmetric algorithm improves the registration. Methods: A robust symmetric registration algorithm is proposed that simultaneously optimises a half space transform and its inverse. During the registration process, the two input volumetric images are transformed to a common position in space, therefore minimising any computational bias. An asymmetrical implementation of the same algorithm was used for comparison purposes. Results: Whole pelvis MRI and CT scans from 15 prostate patients were registered, as in the creation of MR-CT atlases. In each case, two registrations were performed, with different input image orders, and the transformation error quantified. Mean residuals of 0.63±0.26 mm (translation) and (8.7±7.3) × 10 -3 rad (rotation) were found for the asymmetrical implementation with corresponding values of 0.038±0.039 mm and (1.6 ± 1.3) × 10 -3 rad for the proposed symmetric algorithm, a substantial improvement. Conclusions: The increased registration precision will enhance the generation of pseudo-CT from MRI for atlas based MR planning methods. © Published under licence by IOP Publishing Ltd.

DOI 10.1088/1742-6596/489/1/012039
Citations Scopus - 8Web of Science - 7
2014 Ghose S, Holloway L, Lim K, Chan P, Veera J, Vinod SK, et al., 'A review of segmentation and deformable registration methods applied to adaptive cervical cancer radiation therapy treatment planning', Artificial Intelligence in Medicine, (2014) [C1]

Objective: Manual contouring and registration for radiotherapy treatment planning and online adaptation for cervical cancer radiation therapy in computed tomography (CT) and magne... [more]

Objective: Manual contouring and registration for radiotherapy treatment planning and online adaptation for cervical cancer radiation therapy in computed tomography (CT) and magnetic resonance images (MRI) are often necessary. However manual intervention is time consuming and may suffer from inter or intra-rater variability. In recent years a number of computer-guided automatic or semi-automatic segmentation and registration methods have been proposed. Segmentation and registration in CT and MRI for this purpose is a challenging task due to soft tissue deformation, inter-patient shape and appearance variation and anatomical changes over the course of treatment. The objective of this work is to provide a state-of-the-art review of computer-aided methods developed for adaptive treatment planning and radiation therapy planning for cervical cancer radiation therapy. Methods: Segmentation and registration methods published with the goal of cervical cancer treatment planning and adaptation have been identified from the literature (PubMed and Google Scholar). A comprehensive description of each method is provided. Similarities and differences of these methods are highlighted and the strengths and weaknesses of these methods are discussed. A discussion about choice of an appropriate method for a given modality is provided. Results: In the reviewed papers a Dice similarity coefficient of around 0.85 along with mean absolute surface distance of 2-4. mm for the clinically treated volume were reported for transfer of contours from planning day to the treatment day. Conclusions: Most segmentation and non-rigid registration methods have been primarily designed for adaptive re-planning for the transfer of contours from planning day to the treatment day. The use of shape priors significantly improved segmentation and registration accuracy compared to other models.

DOI 10.1016/j.artmed.2015.04.006
Citations Scopus - 7Web of Science - 5
2014 McCowan PM, Rickey DW, Rowshanfarzad P, Greer PB, Ansbacher W, McCurdy BM, 'An investigation of gantry angle data accuracy for cine-mode EPID images acquired during arc IMRT', Journal of Applied Clinical Medical Physics, 15 187-201 (2014) [C1]
Citations Scopus - 12Web of Science - 12
2014 Monville ME, Kuncic Z, Greer PB, 'Simulation of real-time EPID images during IMRT using Monte-Carlo', PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS, 30 326-330 (2014) [C1]
DOI 10.1016/j.ejmp.2013.10.002
Citations Scopus - 2Web of Science - 1
2014 Dowling JA, Burdett N, Greer PB, Sun J, Parker J, Pichler P, et al., 'Automatic Atlas Based Electron Density and Structure Contouring for MRI-based Prostate Radiation Therapy on the Cloud', Journal of Physics: Conference Series, 489 (2014) [E1]

Our group have been developing methods for MRI-alone prostate cancer radiation therapy treatment planning. To assist with clinical validation of the workflow we are investigating ... [more]

Our group have been developing methods for MRI-alone prostate cancer radiation therapy treatment planning. To assist with clinical validation of the workflow we are investigating a cloud platform solution for research purposes. Benefits of cloud computing can include increased scalability, performance and extensibility while reducing total cost of ownership. In this paper we demonstrate the generation of DICOM-RT directories containing an automatic average atlas based electron density image and fast pelvic organ contouring from whole pelvis MR scans. © Published under licence by IOP Publishing Ltd.

DOI 10.1088/1742-6596/489/1/012048
Citations Scopus - 5Web of Science - 4
Co-authors Peter Stanwell
2014 Lee D, Greer PB, Arm J, Keall P, Kim T, 'Audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI', Journal of Physics: Conference Series, 489 1-4 (2014) [E1]
DOI 10.1088/1742-6596/489/1/012033
Citations Scopus - 6Web of Science - 5
2014 Blake SJ, McNamara AL, Vial P, Holloway L, Greer PB, Kuncic Z, 'Monte Carlo simulation of the transit dosimetric response of an a-Si electronic portal imaging device', Journal of Physics: Conference Series, 489 1-6 (2014) [C1]
DOI 10.1088/1742-6596/489/1/012005
Citations Scopus - 2Web of Science - 2
2014 Monville ME, Kuncic Z, Greer PB, 'An improved Monte-Carlo model of the Varian EPID separating support arm and rear-housing backscatter', XVII INTERNATIONAL CONFERENCE ON THE USE OF COMPUTERS IN RADIATION THERAPY (ICCR 2013), 489 (2014) [E1]
DOI 10.1088/1742-6596/489/1/012012
2014 McCowan PM, Rickey DW, Rowshanfarzad P, Greer PB, Ansbacher W, McCurdy BM, 'An investigation of gantry angle data accuracy for cine-mode EPID images acquired during arc IMRT.', Journal of applied clinical medical physics / American College of Medical Physics, 15 4507 (2014)

EPID images acquired in cine mode during arc therapy have inaccurate gantry angles recorded in their image headers. In this work, methods were developed to assess the accuracy of ... [more]

EPID images acquired in cine mode during arc therapy have inaccurate gantry angles recorded in their image headers. In this work, methods were developed to assess the accuracy of the gantry potentiometer for linear accelerators. As well, assessments of the accuracy of other, more accessible, sources of gantry angle information (i.e., treatment log files, analysis of EPID image headers) were investigated. The methods used in this study are generally applicable to any linear accelerator unit, and have been demonstrated here with Clinac/Trilogy systems. Gantry angle data were simultaneously acquired using three methods: i) a direct gantry potentiometer measurement, ii) an incremental rotary encoder, and iii) a custom-made radiographic gantry-angle phantom which produced unique wire intersections as a function of gantry angle. All methods were compared to gantry angle data from the EPID image header and the linac MLC DynaLog file. The encoder and gantry-angle phantom were used to validate the accuracy of the linac's potentiometer. The EPID image header gantry angles and the DynaLog file gantry angles were compared to the potentiometer. The encoder and gantry-angle phantom mean angle differences with the potentiometer were 0.13° ± 0.14° and 0.10°± 0.30°, respectively. The EPID image header angles analyzed in this study were within ± 1° of the potentiometer angles only 35% of the time. In some cases, EPID image header gantry angles disagreed by as much as 3° with the potentiometer. A time delay in frame acquisition was determined using the continuous acquisition mode of the EPID. After correcting for this time delay, 75% of the header angles, on average, were within ± 1° of the true gantry angle, compared to an average of only 35% without the correction. Applying a boxcar smoothing filter to the corrected gantry angles further improved the accuracy of the header-derived gantry angles to within ± 1° for almost all images (99.4%). An angle accuracy of 0.11° ± 0.04° was determined using a point-by-point comparison of the gantry angle data in the MLC DynaLog file and the potentiometer data. These simple correction methods can be easily applied to individual treatment EPID images in order to more accurately define the gantry angle.

2013 Blake SJ, Vial P, Holloway L, Greer PB, McNamara AL, Kuncic Z, 'Characterization of optical transport effects on EPID dosimetry using Geant4', MEDICAL PHYSICS, 40 (2013) [C1]
DOI 10.1118/1.4794479
Citations Scopus - 8Web of Science - 8
2013 Woodruff HC, Fuangrod T, Rowshanfarzad P, McCurdy BMC, Greer PB, 'Gantry-angle resolved VMAT pretreatment verification using EPID image prediction', MEDICAL PHYSICS, 40 (2013) [C1]
DOI 10.1118/1.4816384
Citations Scopus - 26Web of Science - 25
2013 Blake SJ, McNamara AL, Deshpande S, Holloway L, Greer PB, Kuncic Z, Vial P, 'Characterization of a novel EPID designed for simultaneous imaging and dose verification in radiotherapy', MEDICAL PHYSICS, 40 (2013) [C1]
DOI 10.1118/1.4816657
Citations Scopus - 6Web of Science - 6
2013 Fuangrod T, Woodruff HC, Van Uytven E, McCurdy BMC, Kuncic Z, O'Connor DJ, Greer PB, 'A system for EPID-based real-time treatment delivery verification during dynamic IMRT treatment', Medical Physics, 40 (2013) [C1]
DOI 10.1118/1.4817484
Citations Scopus - 18Web of Science - 16
Co-authors John Oconnor
2013 Chytyk-Praznik K, VanUytven E, vanBeek TA, Greer PB, McCurdy BMC, 'Model-based prediction of portal dose images during patient treatment', Medical Physics, 40 (2013) [C1]
DOI 10.1118/1.4792203
Citations Scopus - 18Web of Science - 19
2013 King BW, Greer PB, 'A method for removing arm backscatter from EPID images', Medical Physics, 40 (2013) [C1]
DOI 10.1118/1.4807640
Citations Scopus - 4Web of Science - 3
2013 McNamara AL, Blake SJ, Vial P, Holloway L, Greer PB, Kuncic Z, 'Evaluating radiation damage to scintillating plastic fibers with Monte Carlo simulations', MEDICAL IMAGING 2013: PHYSICS OF MEDICAL IMAGING, 8668 (2013) [E1]
DOI 10.1117/12.2007819
2013 Ghose S, Holloway L, Lim K, Chan P, Veera J, Vinod SK, et al., 'A survey of cervix segmentation methods in magnetic resonance images', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 8198 LNCS 290-298 (2013) [C1]

Radiotherapy is an effective therapy in the treatment of cervix cancer. However tumor and normal tissue motion and shape deformation of the cervix, the bladder and the rectum over... [more]

Radiotherapy is an effective therapy in the treatment of cervix cancer. However tumor and normal tissue motion and shape deformation of the cervix, the bladder and the rectum over the course of the treatment can limit the efficacy of radiotherapy and safe delivery of the dose. A number of studies have presented the potential benefits of adaptive radiotherapy for cervix cancer with high soft tissue contrast magnetic resonance images. To enable practical implementation of adaptive radiotherapy for the cervix, computer aided segmentation is necessary. Accurate computer aided automatic or semi-automatic segmentation of the cervix is a challenging task due to inter patient shape variation, soft tissue deformation, organ motion, and anatomical changes during the course of the treatment. This article reviews the methods developed for cervix segmentation in magnetic resonance images. The objective of this work is to present different methods for cervix segmentation in the literature highlighting their similarities, differences, strengths and weaknesses. © 2013 Springer-Verlag.

DOI 10.1007/978-3-642-41083-3_32
2013 Singh J, Greer PB, White MA, Parker J, Patterson J, Tang CI, et al., 'Treatment-Related Morbidity in Prostate Cancer: A Comparison of 3-Dimensional Conformal Radiation Therapy With and Without Image Guidance Using Implanted Fiducial Markers', INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS, 85 1018-1023 (2013) [C1]
DOI 10.1016/j.ijrobp.2012.07.2376
Citations Scopus - 25Web of Science - 22
Co-authors Jim Denham
2013 Thwaites D, Baldock C, Price L, Starkey E, Whitaker M, Greer P, et al., 'Journal of Physics: Conference Series - Preface', Journal of Physics: Conference Series, 444 (2013)
DOI 10.1088/1742-6596/444/1/011001
2013 Woodruff HC, Greer PB, '3D Dose reconstruction: Banding artefacts in cine mode EPID images during VMAT delivery', Journal of Physics: Conference Series, 444 012042 (2013) [E1]
DOI 10.1088/1742-6596/444/1/012042
Citations Scopus - 4Web of Science - 3
2012 Rowshan Farzad P, Sabet M, O'Connor JD, Greer PB, 'Investigation of the sag in linac secondary collimator and MLC carriage during arc deliveries', Physics in Medicine and Biology, 57 N209-N224 (2012) [C1]
Citations Scopus - 11Web of Science - 10
Co-authors John Oconnor
2012 Herschtal A, Foroudi F, Greer PB, Eade TN, Hindson BR, Kron T, 'Finding the optimal statistical model to describe target motion during radiotherapy delivery-a Bayesian approach', Physics in Medicine and Biology, 57 2743-2755 (2012) [C1]
Citations Scopus - 4Web of Science - 4
2012 Sabet M, Rowshan Farzad P, Vial P, Menk FW, Greer PB, 'Transit dosimetry in IMRT with an a-Si EPID in direct detection configuration', Physics in Medicine and Biology, 57 N295-N306 (2012) [C1]
Citations Scopus - 7Web of Science - 5
Co-authors Fred Menk
2012 King BW, Morf D, Greer PB, 'Development and testing of an improved dosimetry system using a backscatter shielded electronic portal imaging device', Medical Physics, 39 2839-2847 (2012) [C1]
Citations Scopus - 10Web of Science - 11
2012 Chandra SS, Dowling JA, Shen K-K, Raniga P, Pluim JPW, Greer PB, et al., 'Patient specific prostate segmentation in 3-D magnetic resonance images', IEEE Transactions on Medical Imaging, 31 1955-1964 (2012) [C1]
Citations Scopus - 38Web of Science - 34
2012 Rowshan Farzad P, Sabet M, O'Connor JD, Greer PB, 'Improvement of Varian a-Si EPID dosimetry measurements using a lead-shielded support-arm', Medical Dosimetry, 37 145-151 (2012) [C1]
Citations Scopus - 3Web of Science - 3
Co-authors John Oconnor
2012 Rowshan Farzad P, Sabet M, O'Connor JD, Greer PB, 'Impact of backscattered radiation from the bunker structure on EPID dosimetry', Journal of Applied Clinical Medical Physics, 13 91-100 (2012) [C1]
Citations Scopus - 1Web of Science - 1
Co-authors John Oconnor
2012 Rowshan Farzad P, Sabet M, O'Connor JD, McCowan PM, McCurdy BMC, Greer PB, 'Gantry angle determination during arc IMRT: evaluation of a simple EPID-based technique and two commercial inclinometers', Journal of Applied Clinical Medical Physics, 13 203-214 (2012) [C1]
Citations Scopus - 13Web of Science - 8
Co-authors John Oconnor
2012 Rowshan Farzad P, Sabet M, O'Connor JD, McCowan PM, McCurdy BMC, Greer PB, 'Detection and correction for EPID and gantry sag during arc delivery using cine EPID imaging', Medical Physics, 39 623-635 (2012) [C1]
Citations Scopus - 34Web of Science - 33
Co-authors John Oconnor
2012 Rowshan Farzad P, Sabet M, Barnes MP, O'Connor JD, Greer PB, 'EPID-based verification of the MLC performance for dynamic IMRT and VMAT', Medical Physics, 39 6192-6207 (2012) [C1]
DOI 10.1118/1.4752207
Citations Scopus - 24Web of Science - 22
Co-authors John Oconnor
2012 Dowling JA, Lambert JA, Parker J, Salvado O, Fripp J, Capp A, et al., 'An atlas-based electron density mapping method for Magnetic Resonance Imaging (MRI)-Alone treatment planning and adaptive MRI-Based prostate radiation therapy', International Journal of Radiation Oncology Biology Physics, 83 E5-E11 (2012) [C1]
Citations Scopus - 98Web of Science - 86
Co-authors Jim Denham
2012 Blake S, Vial P, Holloway L, McNamara A, Greer P, Kuncic Z, 'SU-E-I-109: Sensitivity Analysis of an Electronic Portal Imaging Device Monte Carlo Model to Variations in Optical Transport Parameters.', Med Phys, 39 3650 (2012)
DOI 10.1118/1.4734826
2011 Rowshan Farzad P, Sabet M, O'Connor JD, Greer PB, 'Isocenter verification for linac-based stereotactic radiation therapy: review of principles and techniques', Journal of Applied Clinical Medical Physics, 12 12 (2011) [C1]
Citations Scopus - 15Web of Science - 9
Co-authors John Oconnor
2011 Chandra S, Dowling J, Shen K, Pluim J, Greer PB, Salvado O, Fripp J, 'Automatic segmentation of the prostate in 3D magnetic resonance images using case specific deformable models', Proceedings: 2011 International Conference on Digital Image Computing: Techniques and Applications, DICTA 2011, 7-12 (2011) [E1]
DOI 10.1109/DICTA.2011.10
Citations Scopus - 4
2011 Greer PB, Dowling JA, Lambert JA, Fripp J, Parker J, Denham J, et al., 'A magnetic resonance imaging-based workflow for planning radiation therapy for prostate cancer', Medical Journal of Australia, 194 S24-S27 (2011) [C1]
Citations Scopus - 21Web of Science - 17
Co-authors Jim Denham
2011 Rowshan Farzad P, Sabet M, O'Connor JD, Greer PB, 'Verification of the linac isocenter for stereotactic radiosurgery using cine-EPID imaging and arc delivery', Medical Physics, 38 3963-3970 (2011) [C1]
DOI 10.1118/1.3597836
Citations Scopus - 25Web of Science - 23
Co-authors John Oconnor
2011 Gustafsson H, Vial P, Kuncic Z, Baldock C, Denham J, Greer PB, 'Direct dose to water dosimetry for pretreatment IMRT verification using a modified EPID', Medical Physics, 38 6257-6264 (2011) [C1]
DOI 10.1118/1.3656946
Citations Scopus - 5Web of Science - 4
Co-authors Jim Denham
2011 Hatton J, Greer PB, Tang C, Wright P, Capp A, Gupta S, et al., 'Does the planning dose-volume histogram represent treatment doses in image-guided prostate radiation therapy? Assessment with cone-beam computerised tomography scans', Radiotherapy and Oncology, 98 162-168 (2011) [C1]
DOI 10.1016/j.radonc.2011.01.006
Citations Scopus - 45Web of Science - 40
Co-authors Jim Denham, Joan Hatton
2011 Lambert JA, Greer PB, Menk FW, Patterson J, Parker J, Dahl K, et al., 'MRI-guided prostate radiation therapy planning: Investigation of dosimetric accuracy of MRI-based dose planning', Radiotherapy and Oncology, 98 330-334 (2011) [C1]
DOI 10.1016/j.radonc.2011.01.012
Citations Scopus - 60Web of Science - 47
Co-authors Jim Denham, Fred Menk
2011 King BW, Clews L, Greer PB, 'Long-term two-dimensional pixel stability of EPIDs used for regular linear accelerator quality assurance', Australasian Physical & Engineering Sciences in Medicine, 34 459-466 (2011) [C1]
Citations Scopus - 6Web of Science - 6
2010 Ansbacher W, Swift C-L, Greer PB, 'An evaluation of cine-mode 3D portal image dosimetry for volumetric modulated arc therapy', Journal of Physics: Conference Series, 012022 (2010) [E1]
DOI 10.1088/1742-6596/250/1/012022
Citations Scopus - 12
2010 Rowshan Farzad P, McCurdy BMC, Sabet M, Lee CG, O'Connor JD, Greer PB, 'Measurement and modeling of the effect of support arm backscatter on dosimetry with a Varian EPID', Medical Physics, 37 2269-2278 (2010) [C1]
DOI 10.1118/1.3369445
Citations Scopus - 38Web of Science - 36
Co-authors John Oconnor
2010 Sabet M, Menk FW, Greer PB, 'Evaluation of an a-Si EPID in direct detection configuration as a water-equivalent dosimeter for transit dosimetry', Medical Physics, 37 1459-1467 (2010) [C1]
DOI 10.1118/1.3327456
Citations Scopus - 20Web of Science - 18
Co-authors Fred Menk
2010 Rowshan Farzad P, Sabet M, O'Connor JD, Greer PB, 'Reduction of the effect of non-uniform backscatter from an E-type support arm of a Varian a-Si EPID used for dosimetry', Physics in Medicine and Biology, 55 6617-6632 (2010) [C1]
DOI 10.1088/0031-9155/55/22/003
Citations Scopus - 9Web of Science - 8
Co-authors John Oconnor
2009 Ebert MA, Kenny J, Greer PB, 'Experience converting an RT department to full CT simulation: Technical issues identified during commissioning of a wide-bore scanner', Journal of Medical Imaging and Radiation Oncology, 53 325-330 (2009) [C1]
DOI 10.1111/j.1440-1673.2009.02075.x
Citations Scopus - 3Web of Science - 2
2009 Hatton J, McCurdy B, Greer PB, 'Cone beam computerized tomography: The effect of calibration of the Hounsfield unit number to electron density on dose calculation accuracy for adaptive radiation therapy', Physics in Medicine and Biology, 54 N329-N346 (2009) [C1]
DOI 10.1088/0031-9155/54/15/n01
Citations Scopus - 73Web of Science - 58
Co-authors Joan Hatton
2009 Gardner JK, Clews L, Gordon JJ, Wang S, Greer PB, Siebers JV, 'Comparison of sources of exit fluence variation for IMRT', Physics in Medicine and Biology, 54 N451-N458 (2009) [C1]
DOI 10.1088/0031-9155/54/19/n03
Citations Scopus - 1
2009 Vial P, Gustafsson H, Oliver L, Baldock C, Greer PB, 'Direct-detection EPID dosimetry: Investigation of a potential clinical configuration for IMRT verification', Physics in Medicine and Biology, 54 7151-7169 (2009) [C1]
DOI 10.1088/0031-9155/54/23/008
Citations Scopus - 7Web of Science - 6
2009 McCurdy BMC, Greer PB, 'Dosimetric properties of an amorphous-silicon EPID used in continuous acquisition mode for application to dynamic and arc IMRT', Medical Physics, 36 3028-3039 (2009) [C1]
DOI 10.1118/1.3148822
Citations Scopus - 57Web of Science - 53
2009 Greer PB, Cadman P, Lee CG, Bzdusek K, 'An energy fluence-convolution model for amorphous silicon EPID dose prediction', Medical Physics, 36 547-555 (2009) [C1]
DOI 10.1118/1.3058481
Citations Scopus - 20Web of Science - 20
2009 Lee CG, Menk FW, Cadman P, Greer PB, 'A simple approach to using an amorphous silicon EPID to verify IMRT planar dose maps', Medical Physics, 36 984-992 (2009) [C1]
DOI 10.1118/1.3075817
Citations Scopus - 22Web of Science - 22
Co-authors Fred Menk
2009 Wang S, Gardner JK, Gordon JJ, Li W, Clews L, Greer PB, Siebers JV, 'Monte Carlo-based adaptive EPID dose kernel accounting for different field size responses of imagers', Medical Physics, 36 3582-3595 (2009) [C1]
DOI 10.1118/1.3158732
Citations Scopus - 14Web of Science - 13
2009 Clews L, Greer PB, 'An EPID based method for efficient and precise asymmetric jaw alignment quality assurance', Medical Physics, 36 5488-5496 (2009) [C1]
DOI 10.1118/1.3253463
Citations Scopus - 10Web of Science - 9
2009 Gustafsson H, Vial P, Kuncic Z, Baldock C, Greer PB, 'EPID dosimetry: Effect of different layers of materials on absorbed dose response', Medical Physics, 36 5665-5674 (2009) [C1]
DOI 10.1118/1.3245886
Citations Scopus - 12Web of Science - 12
2009 Haworth A, Kearvell R, Greer PB, Hooton B, Denham J, Lamb D, et al., 'Assuring high quality treatment delivery in clinical trials: Results from the Trans-Tasman Radiation Oncology Group (TROG) study 03.04 'RADAR' set-up accuracy study', Radiotherapy and Oncology, 90 299-306 (2009) [C1]
DOI 10.1016/j.radonc.2008.10.011
Citations Scopus - 27Web of Science - 27
Co-authors Jim Denham
2009 Denham J, Kumar M, Gleeson PS, Lamb DS, Joseph D, Atkinson C, et al., 'Recognizing false biochemical failure calls after radiation with or without neo-adjuvant androgen deprivation for prostate cancer', International Journal of Radiation Oncology Biology Physics, 74 404-411 (2009) [C1]
DOI 10.1016/j.ijrobp.2008.08.047
Citations Scopus - 11Web of Science - 9
Co-authors Jim Denham, Catherine Deste, Allison Steigler
2009 Denham J, Steigler A, Kumar M, Lamb DS, Joseph D, Spry NA, et al., 'Measuring time to biochemical failure in the Trog 96.01 trial: When should the clock start ticking?', International Journal of Radiation Oncology Biology Physics, 75 1008-1012 (2009) [C1]
DOI 10.1016/j.ijrobp.2008.12.085
Citations Scopus - 7Web of Science - 6
Co-authors Allison Steigler, Catherine Deste, Jim Denham
2009 McCurdy BMC, Greer PB, 'Dosimetric properties of an amorphous-silicon EPID used in continuous acquisition mode for application to dynamic and arc IMRT.', Med Phys, 36 3028-3039 (2009)
DOI 10.1118/1.3148822
2008 Denham J, Steigler A, Wilcox C, Lamb DS, Joseph D, Atkinson C, et al., 'Time to biochemical failure and prostate-specific antigen doubling time as surrogates for prostate cancer-specific mortality: evidence from the TROG 96.01 randomised controlled trial', Lancet Oncology, 9 1058-1068 (2008) [C1]
DOI 10.1016/s1470-2045(08)70236-5
Citations Scopus - 58Web of Science - 53
Co-authors Allison Steigler, Catherine Deste, Jim Denham
2008 Greer PB, Dahl K, Ebert MA, White M, Wratten C, Ostwald PM, et al., 'Assessment of a daily online implanted fiducial marker-guided prostate radiotherapy process', Journal of Medical Imaging and Radiation Oncology, 52 517-524 (2008) [C1]
DOI 10.1111/j.1440-1673.2008.02006.x
Citations Scopus - 5Web of Science - 4
Co-authors Patricia Ostwald, Jim Denham
2008 Greer PB, Dahl K, Ebert MA, Wratten C, White M, Denham J, 'Comparison of prostate set-up accuracy and margins with off-line bony anatomy corrections and online implanted fiducial-based corrections', Journal of Medical Imaging and Radiation Oncology, 52 511-516 (2008) [C1]
DOI 10.1111/j.1440-1673.2008.02005.x
Citations Scopus - 21Web of Science - 21
Co-authors Jim Denham
2008 Vial P, Greer PB, Hunt P, Oliver L, Baldock C, 'The impact of MLC transmitted radiation on EPID dosimetry for dynamic MLC beams', Medical Physics, 35 1267-1277 (2008) [C1]
DOI 10.1118/1.2885368
Citations Scopus - 40Web of Science - 41
2008 Vial P, Greer PB, Oliver L, Baldock C, 'Initial evaluation of a commercial EPID modified to a novel direct-detection configuration for radiotherapy dosimetry', Medical Physics, 35 4362-4374 (2008) [C1]
DOI 10.1118/1.2975156
Citations Scopus - 22Web of Science - 19
2008 Vial P, Hunt P, Greer PB, Oliver L, Baldock C, 'Software tool for portal dosimetry research', Australasian Physical & Engineering Sciences in Medicine, 31 216-222 (2008) [C1]
DOI 10.1007/BF03179347
Citations Scopus - 2Web of Science - 2
2008 Ebert MA, Lambert JA, Greer PB, 'CT-ED conversion on a GE Lightspeed-RT scanner: Influence of scanner settings', Australasian Physical and Engineering Sciences in Medicine, 31 154-159 (2008) [C1]
DOI 10.1007/BF03178591
Citations Scopus - 8Web of Science - 5
2007 Greer PB, Barnes MP, 'Investigation of an amorphous silicon EPID for measurement and quality assurance of enhanced dynamic wedge', Physics in Medicine and Biology, 52 1075-1087 (2007) [C1]
DOI 10.1088/0031-9155/52/4/014
Citations Scopus - 20Web of Science - 20
2007 Greer PB, 'Off-axis dose response characteristics of an amorphous silicon electronic portal imaging device', Medical Physics, 34 3815-3824 (2007) [C1]
DOI 10.1118/1.2779944
Citations Scopus - 27Web of Science - 29
2007 Greer PB, Vial P, Oliver L, Baldock C, 'Experimental investigation of the response of an amorphous silicon EPID to intensity modulated radiotherapy beams', Medical Physics, 34 4389-4398 (2007) [C1]
DOI 10.1118/1.2789406
Citations Scopus - 44Web of Science - 41
2006 Vial P, Oliver L, Greer PB, Baldock C, 'An experimental investigation into the radiation field offset of a dynamic multileaf collimator', Physics in Medicine and Biology, 51 5517-5538 (2006) [C1]
DOI 10.1088/0031-9155/51/21/009
Citations Scopus - 20Web of Science - 18
2005 Greer PB, 'Correction of pixel sensitivity variation and off-axis response for amorphous silicon EPID dosimetry', Medical Physics, 32 3558-3578 (2005) [C1]
DOI 10.1118/1.2128498
Citations Scopus - 73Web of Science - 73
2005 Ludbrook JJS, Greer PB, Blood P, D'Yachkova Y, Coldman A, Beckham WA, et al., 'Correction Of Systematic Setup Errors in Prostate Radiation Therapy: How Many Images to Perform?', Medical Dosimetry, 30 76-84 (2005) [C1]
DOI 10.1016/j.meddos.2005.03.003
Citations Scopus - 16Web of Science - 16
2003 Greer PB, Beckham WA, 'Improving the resolution of intensity modulated delivery by reducing the MLC leaf sampling distance', Medical Physics, 30 2793-2801 (2003) [C1]
DOI 10.1118/1.1609992
Citations Scopus - 1Web of Science - 2
2003 Greer PB, Popescue CC, 'Dosimetric properties of an amorphous silicon electronic portal imaging device for verification of dynamic intensity modulated radiation therapy', Medical Physics, 30 1618-1627 (2003) [C1]
DOI 10.1118/1.1582469
Citations Scopus - 167Web of Science - 153
2003 Greer PB, Beckham WA, 'The effect of leaf width and sampling distance on the ''stair-stepping'' of field borders defined by multileaf collimators', Australasian Physical and Engineering Sciences in Medicine, 26 44-51 (2003) [C1]
DOI 10.1007/BF03178457
Citations Scopus - 2
2000 Greer PB, van Doorn T, 'Evaluation of an algorithm for the assessment of the MTF using an edge method', MEDICAL PHYSICS, 27 2048-2059 (2000)
DOI 10.1118/1.1288682
Citations Scopus - 75Web of Science - 63
2000 Greer PB, van Doom T, 'A design for a dual assembly multileaf collimator', MEDICAL PHYSICS, 27 2242-2255 (2000)
DOI 10.1118/1.1290731
Citations Scopus - 2Web of Science - 2
1998 Greer PB, Jose CC, Matthews JHL, 'Set-up variation of patients treated with radiotherapy to the prostate measured with an electronic portal imaging device', Australasian Radiology, 42 207-212 (1998)

The set-up variation of 11 patients treated supine with radical radiotherapy for carcinoma of the prostate was measured with an electronic portal imaging device to determine the a... [more]

The set-up variation of 11 patients treated supine with radical radiotherapy for carcinoma of the prostate was measured with an electronic portal imaging device to determine the adequacy of set-up techniques and current margins, as well as the need for immobilization. During the treatments 172 images of the anterior fields and 159 images of the left- lateral fields were taken and the errors in treatment placement were measured by template matching. The variation in the superior-inferior direction was small, 1.4-1.6 mm (1 SD), while the medio-lateral variation was 2.8 mm (1 SD). The anterior-posterior variation was largest, 4.6 mm (1 SD) with an offset of 3.3 mm anterior. This anterior offset and large anterior-posterior variation suggests that set-up techniques were not optimal for this direction. The 1 cm margin used was adequate for set-up variation except in a small number of cases, which was mainly due to the anterior trend. Random (treatment-to-treatment) variations were small (1.1-2.3 mm; 1 SD), indicating that immobilization would result in only modest improvement in reproducibility for these supine patients.

Citations Scopus - 14
1998 Greer PB, Mortensen TM, Rad DT, Jose CC, 'Comparison of two methods for anterior-posterior isocenter localization in pelvic radiotherapy using electronic portal imaging', INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS, 41 1193-1199 (1998)
DOI 10.1016/S0360-3016(98)00160-6
Citations Scopus - 32Web of Science - 24
1997 Greer PB, Mortensen TM, 'Anterior-posterior treatment localization in pelvic radiotherapy: Tattoos or fixed couch-to-isocentre distance', Medical Dosimetry, 22 43-46 (1997)

The methods of determining the anterior-posterior isocentre location in pelvic radiotherapy are either by aligning lateral localization lasers to tattoo marks on skin, or by setti... [more]

The methods of determining the anterior-posterior isocentre location in pelvic radiotherapy are either by aligning lateral localization lasers to tattoo marks on skin, or by setting a constant daily couch-to-isocentre distance. While using the former method the day-to-day vertical couch movement was recorded and combined with measurements of day-to-day anterior- posterior patient movement made with an electronic portal imaging device to determine whether couch vertical movement contributes to anterior-posterior setup variation. Seven unimmobilized patients were studied, four supine prostate and three prone rectum patients. The two motions were found to be highly correlated (correlation coefficient = 0.82) which supports the constant couch-to-isocentre distance approach. When the day-to-day couch vertical movement was subtracted from the anterior-posterior movement results the setup variation was reduced in six of the seven patients.

DOI 10.1016/S0958-3947(96)00156-2
Citations Scopus - 5
1996 Greer PB, 'Image timing and detector performance of a matrix ion-chamber electronic portal imaging device', Australasian Physical and Engineering Sciences in Medicine, 19 264-269 (1996)

Image timing and input/output characteristics of a Varian PortalVision¿ matrix liquid ion-chamber electronic portal imaging device (EPID) used with a Varian CL2100C/D linear acce... [more]

Image timing and input/output characteristics of a Varian PortalVision¿ matrix liquid ion-chamber electronic portal imaging device (EPID) used with a Varian CL2100C/D linear accelerator were investigated to examine the variation in image timing and detector performance with acquisition mode. Contrast-detail curves showed that the input/output results were indicative of the image quality variation with acquisition mode. Overall for this accelerator/EPID arrangement the 500 MU/min repetition rate gives the best image quality for the 6 MV and 18 MV acquisition modes.

Citations Scopus - 1
1994 Hodgkinson IJ, Greer PB, Molteno AC, 'Point-spread function for light scattered in the human ocular fundus.', Journal of the Optical Society of America. A, Optics, image science, and vision, 11 479-486 (1994)
1993 Greer PB, Molteno ACB, Hodgkinson IJ, 'Reflected line spread function of the human ocular fundus', Australasian Physical and Engineering Sciences in Medicine, 16 168-173 (1993)
Citations Scopus - 1
Show 124 more journal articles

Review (1 outputs)

Year Citation Altmetrics Link
2013 Greer PB, '3D EPID based dosimetry for pre-treatment verification of VMAT - methods and challenges', Journal of Physics: Conference Series (2013) [E1]
DOI 10.1088/1742-6596/444/1/012010
Citations Scopus - 7Web of Science - 4

Conference (118 outputs)

Year Citation Altmetrics Link
2017 Gholizadeh N, Greer P, Simpson J, Ramadan S, 'Towards MRSI of the prostate cancer using GOIA-sLASER refocusing pulse' (2017)
Co-authors Saadallah Ramadan
2016 Lehmann J, Sun J, Doebrich M, Zwan B, Fuangrod T, Bhatia S, Greer P, 'Implementation of Live EPID-based Inspiration Level Assessment (LEILA) for deepinspiration breath-hold (DIBH) monitoring using MV fluoroscopy', MEDICAL PHYSICS (2016)
DOI 10.1118/1.4958171
2016 Miri N, Lehmann J, Greer P, 'A METHOD FOR REMOTE AUDITING OF RADIOTHERAPY MACHINES', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2016)
2016 Fuangrod T, Simpson J, Greer P, 'TREATMENT QUALITY ASSESSMENT USING IN VIVO ELECTRONIC PORTAL IMAGING DEVICE (EPID) DOSIMETRY IN RADIOTHERAPY', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2016)
2016 Gholizadeh N, Greer P, Simpson J, Arm J, Ramadan S, 'TO EVALUATE THE FEASIBILITY OF MAGNETIC RESONANCE IMAGING (MRSI) USING SEMI-LASER GRADIENT OFFSET INDEPENDENT ADIABATICITY (SLASER-/GOIA) REFOCUSING PULSES FOR THE HUMAN PROSTATE', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2016)
Co-authors Saadallah Ramadan
2016 Gholizadeh N, Greer P, Simpson J, Arm J, Ramadan S, 'CALIBRATION OF APPARENT DIFFUSION COEFFICIENT (ADC) VALUE ON TWO DIFFERENT WHOLE BODY MAGNETIC RESONANCE (MR) SCANNERS USING ICE-WATER PHANTOM', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2016)
Co-authors Saadallah Ramadan
2016 DeMarco J, Moran J, Barnes M, Greer P, Kim G, Fraass B, et al., 'SU-F-T-476: Performance of the AS1200 EPID for Periodic Photon Quality Assurance.', Med Phys (2016)
DOI 10.1118/1.4956661
2016 Miri N, Lehmann J, Vial P, Legge K, Greer P, 'TU-FG-201-06: Remote Dosimetric Auditing for Clinical Trials Using EPID Dosimetry: A Pilot Study.', Med Phys (2016)
DOI 10.1118/1.4957529
2016 Ritter T, Schultz B, Kim G, Barnes M, Perez M, Farrey K, et al., 'SU-G-TeP4-07: Automatic EPID-Based 2D Measurement of MLC Leaf Offset as a Quality Control Tool.', Med Phys (2016)
DOI 10.1118/1.4957132
2016 Legge K, Lehmann J, Vial P, Miri N, Greer P, 'SU-D-201-06: Remote Dosmetric Auditing of VMAT Deliveries for Clinical Trials Using EPID.', Med Phys (2016)
DOI 10.1118/1.4955618
2016 Nguyen D, Kim J, O'Brien R, Huang C, Booth J, Greer P, et al., 'TH-AB-202-12: The First Clinical Implementation of a Real-Time Six Degree of Freedom Tracking System During Radiation Therapy.', Med Phys (2016)
DOI 10.1118/1.4958076
Co-authors Jarad Martin
2016 Legge K, Nguyen D, Ng J, Wilton L, Booth J, Keall P, et al., 'SU-G-JeP4-10: Measurement of Prostate Motion Trajectories During Prostate SBRT Boost Treatments with a Rectafix.', Med Phys (2016)
DOI 10.1118/1.4957120
Co-authors John Oconnor, Jarad Martin
2016 Legge K, Cutajar D, Wilfert A, Martin J, Rozenfeld A, O'Connor DJ, Greer P, 'SU-F-T-328: Real-Time in Vivo Dosimetry of Prostate SBRT Boost Treatments Using MOSkin Detectors.', Med Phys (2016)
DOI 10.1118/1.4956513
Co-authors John Oconnor, Jarad Martin
2016 Miri N, Lehmann J, Vial P, Greer P, 'SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing.', Med Phys (2016)
DOI 10.1118/1.4956380
2016 Greer P, 'TU-D-BRC-02: Free Information - EPID-Based In Vivo Dosimetry.', Med Phys (2016)
DOI 10.1118/1.4957479
2016 Fuangrod T, Simpson J, Middleton R, Greer P, 'TH-CD-207A-11: Sensitivity Analysis of Action Limits for Real-Time EPID-Based Delivery Verification System Using Artificial Clinical Relevant Error Simulations.', Med Phys (2016)
DOI 10.1118/1.4958180
Co-authors Richard Middleton
2016 Zwan BJ, Barnes M, Hindmarsh J, Seymour E, O'Connor DJ, Keall PJ, Greer PB, 'MO-FG-202-04: Gantry-Resolved Linac QA for VMAT: A Comprehensive and Efficient System Using An Electronic Portal Imaging Device.', Med Phys (2016)
DOI 10.1118/1.4957306
Co-authors John Oconnor
2016 Lee D, Greer P, Lapuz C, Ludbrook J, Pollock S, Kim T, Keall P, 'MO-FG-CAMPUS-JeP2-02: Audiovisual Biofeedback Guided Respiratory-Gated MRI: An Investigation of Tumor Definition and Scan Time for Lung Cancer.', Med Phys (2016)
DOI 10.1118/1.4957355
2016 David R, Zwan B, Hindmarsh J, Seymour E, Kandasamy K, Arthur G, et al., 'MO-FG-CAMPUS-TeP1-01: An Efficient Method of 3D Patient Dose Reconstruction Based On EPID Measurements for Pre-Treatment Patient Specific QA.', Med Phys (2016)
DOI 10.1118/1.4957343
2015 Lee D, Greer P, Lapuz C, Ludbrook J, Pollock S, Kim T, Keall P, 'Audiovisual Biofeedback Improves Breath-Hold Lung Tumor Position Reproducibility Measured with 4D MRI', Medical Physics (2015) [E3]
DOI 10.1118/1.4924322
2015 Lee D, Greer P, Ludbrook J, Paganelli C, Pollock S, Kim T, Keall P, 'Audiovisual Biofeedback Improves the Correlation Between Internal and External Respiratory Motion', MEDICAL PHYSICS (2015) [E3]
2015 Miri N, Baltes C, Keller P, Greer P, 'Development of Dose-To-Water Conversion Models for Pre-Treatment Verification with the New AS1200 Imager', MEDICAL PHYSICS (2015) [E3]
Citations Web of Science - 1
2015 Lehmann J, Miri N, Vial P, Hatton J, Zwan B, Craig A, et al., 'Remote Dosimetric Credentialing for Clinical Trials with the Virtual EPID Standard Phantom Audit (VESPA)', MEDICAL PHYSICS (2015) [E3]
Citations Web of Science - 1
Co-authors Joan Hatton
2015 Paganelli C, Lee D, Kipritidis J, Greer P, Riboldi M, Keall P, '3D Reconstruction From 2D CineMRI Orthogonal Slices: A Feasibility Study', MEDICAL PHYSICS (2015) [E3]
2015 Lehmann J, Bhatia S, Walsh S, Field M, Barakat M, Greer P, et al., 'SIFTING DATA FROM THE CLINICAL COALFACE: DATAMINING IN RADIATION ONCOLOGY TO AID CLINICAL DECISIONS', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2015) [E3]
2015 Miri N, Lehmann J, Greer P, 'EPID DOSIMETRY FOR CREDENTIALING IMRT TREATMENTS OF DIFFERENT CENTRES', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2015) [E3]
2015 Lehmann J, Miri N, Vial P, Hatton J, Zwan B, Craig A, et al., 'MO-D-213-08: Remote Dosimetric Credentialing for Clinical Trials with the Virtual EPID Standard Phantom Audit (VESPA).', Medical physics (2015) [C3]
DOI 10.1118/1.4925324
Co-authors Joan Hatton
2015 Fuangrod T, Greer P, Middleton R, 'DEVELOPMENT OF ACTION LIMITS FOR PATIENT ERROR DETECTION FOR AN EPID-BASED REAL-TIME DELIVERY VERIFICATION SYSTEM', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2015) [E3]
Co-authors Richard Middleton
2015 Panicker N, Watt L, Kahl R, Dun M, Greer P, Skelding K, Verrills N, 'REDUCED EXPRESSION OF PROTEIN PHOSPHATASE 2A SUBUNIT, B55A, IN BREAST CANCER DNA DAMAGE REPAIR PATHWAYS', ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY (2015) [E3]
Co-authors Nikki Verrills, Kathryn Skelding, Matt Dun
2014 Rivest-Hénault D, Ghose S, Pluim JPW, Greer PB, Fripp J, Dowling JA, 'Fast multiatlas selection using composition of transformations for radiation therapy planning', Medical Computer Vision: Algorithms for Big Data. International Workshop, MCV 2014 Held in Conjunction with MICCAI 2014 Cambridge, MA, USA, September 18, 2014 Revised Selected Papers (2014) [E1]
DOI 10.1007/978-3-319-13972-2_10
Citations Scopus - 2Web of Science - 2
2014 Lee D, Greer P, Arm J, Hunter P, Pollock S, Makhija K, et al., 'SU-E-J-29: Audiovisual Biofeedback Improves Tumor Motion Consistency for Lung Cancer Patients.', Med Phys (2014)
DOI 10.1118/1.4888080
2014 Lee D, Greer P, Pollock S, Whelan B, Kim T, Keall P, 'WE-G-18C-08: Real Time Tumor Imaging Using a Novel Dynamic Keyhole MRI Reconstruction Technique.', Med Phys (2014)
DOI 10.1118/1.4889527
2014 Rivest-Hénault D, Greer P, Fripp J, Dowling J, 'Structure-guided nonrigid registration of CT-MR pelvis scans with large deformations in MR-based image guided radiation therapy', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (2014)

Multimodal registration of CT and MR scans is a required step in leading edge adaptive MR-based image guided radiation therapy protocols. Yet, anatomical changes limit the precisi... [more]

Multimodal registration of CT and MR scans is a required step in leading edge adaptive MR-based image guided radiation therapy protocols. Yet, anatomical changes limit the precision of the registration process and therefore that of the whole intervention. In prostate radiation therapy, the difference in bladder and rectum filling can significantly displace both the targeted area and the organs at risk. Here, we describe a method that integrates an image-based similarity criterion with the anatomical information from manual contours to guide the registration process toward an accurate solution. Whole pelvis CT and MR scans of 33 patients have been nonrigidly registered, and the proposed method leads to an average improvement of 0.17 DSC when compared to a baseline nonrigid registrations. The increased accuracy will thus enhance an MR-based prostate radiation therapy protocol. © 2014 Springer International Publishing.

DOI 10.1007/978-3-319-05666-1_9
Citations Scopus - 4
2013 Vial P, Blake SJ, McNamara AL, Holloway L, Greer PB, Kuncic Z, 'A new concept in detector design for radiation therapy: Simultaneous imaging and dosimetry for comprehensive treatment verification', 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) (2013)
Citations Scopus - 2
2013 Sun J, Dowling J, Menk F, Stanwell P, Salvado O, Parker J, Greer P, 'Investigation on CIVCO coil mount for MR-based prostate treatment planning', Australasian Physical & Engineering Sciences in Medicine (2013) [E3]
DOI 10.1007/s13246-012-0168-7
Co-authors Fred Menk, Peter Stanwell
2013 Greer P, Fuangrod T, Woodruff H, Rowshanfarzad P, van Uytven E, McCurdy B, 'Real-Time EPID-Based Dose Verification System for Detection of Gross Radiation Treatment Delivery Errors', INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS (2013)
2012 Fuangrod T, Woodruff H, Vanuytven E, McCurdy B, O'Connor JD, Greer PB, 'Simulations of real-time geometric and dosimetic verification system using EPID', Medical Physics (2012) [E3]
Citations Web of Science - 1
Co-authors John Oconnor
2012 Blake S, Vial P, Holloway L, McNamara A, Greer PB, Kuncic Z, 'Sensitivity analysis of an electronic portal imaging device Monte Carlo model to variations in optical transport parameters', Medical Physics (2012) [E3]
2012 King BW, Greer PB, 'A method to remove support arm backscatter from EPID images', Medical Physics (2012) [E3]
2012 Vial P, Deshpande S, Blake S, McNamara A, Holloway L, Greer PB, Kuncic Z, 'First experiments of a prototype device for simultaneous imaging and dose verification in radiotherapy', Medical Physics (2012) [E3]
Citations Web of Science - 2
2012 Whelan B, Kumar S, Dowling J, Lambert JA, Lim K, Salvado O, et al., 'Requirements for the accuracy of electron density data planning for MRI based cervix cancer treatment planning', Medical Physics (2012) [E3]
2012 Whelan B, Kumar S, Dowling J, Lambert J, Lim K, Salvado O, et al., 'SU-E-J-179: Requirements for the Accuracy of Electron Density Data Planning for MRI Based Cervix Cancer Treatment Planning.', Med Phys (2012)
DOI 10.1118/1.4735020
2012 Vial P, Deshpande S, Blake S, Mcnamara A, Holloway L, Greer P, Kuncic Z, 'TH-C-BRA-11: First Experiments of a Prototype Device for Simultaneous Imaging and Dose Verification in Radiotherapy', Medical Physics (2012)

Purpose: Current model electronic portal imaging devices (EPIDs) used in radiotherapy are optimised for imaging but problematic for accurate dosimetry. The aim of this project is ... [more]

Purpose: Current model electronic portal imaging devices (EPIDs) used in radiotherapy are optimised for imaging but problematic for accurate dosimetry. The aim of this project is to develop a new EPID capable of simultaneous imaging and water equivalent dosimetry. This work reports our first experimental results. Methods: A prototype device based on a segmented plastic scintillator (SegmentedPS) was developed. The prototype device was tested in comparison with three other detector configurations, all utilising the same a-Si photodiode array used in conventional EPIDs. The configurations tested were; i) standard indirect configuration with phosphor/copper (STANDARD), ii) direct configuration with 1.5 cm solid water build-up (DIRECT), iii) 2 cm thick sheet of plastic scintillator (PSsheet), and iv) 1.5 cm thick prototype SegmentedPS. The sensitivity, dose response and image quality was assessed in each configuration. The dose response was assessed in terms of field size response and off-axis response relative to reference dose in water measurements at the equivalent depth. The image quality was assessed using an image quality phantom. Results: The sensitivity of each device relative to the STANDARD configuration was 0.03(DIRECT), 0.63(PSsheet), and 0.35(SegmentedPS). The agreement in field size response relative to dose in water data for square field sizes 4 cm to 15 cm was within 4.8%(STANDARD), 0.9%(DIRECT), 22%(PSsheet), and 1.3%(SegmentedPS). The agreement in off-axis ratios at 15 cm off-axis, relative to dose in water data, was within 23%(STANARD), 4%(DIRECT), 5%(PSsheet), and 4%(SegmentedPS). Image quality parameters (f50/CNR) for each configuration were 0.41/993(STANDARD), 0.30/167(DIRECT), 0.22/125(PSsheet) and 0.23/214(SegmentedPS). Conclusions: First experiments with the prototype SegmentedPS EPID demonstrated the potential for simultaneous imaging and water equivalent dosimetry. Further design optimisation is required to approach the imaging performance of STANDARD a-Si EPIDs, while maintaining water equivalent dose response. Cancer Council NSW Research Project Grant (RG 11-06) Cancer Institute NSW Research Equipment Grant (10/REG/1-20). © 2012, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.4736327
Citations Scopus - 2
2012 Fuangrod T, Woodruff H, Vanuytven E, Mccurdy B, O'connor D, Greer P, 'MO-G-213AB-03: Simulations of Real-Time Geometric and Dosimetic Verification System Using EPID', Medical Physics (2012)

Purpose: To demonstrate a new method for real-time geometric and dosimetric verification of IMRT and VMAT using synchronization between predicted and measured EPID images. Methods... [more]

Purpose: To demonstrate a new method for real-time geometric and dosimetric verification of IMRT and VMAT using synchronization between predicted and measured EPID images. Methods: Predicted EPID images were calculated using a comprehensive physics-based model. Each predicted image represents the integrated signal expected from the delivery between control points. The measured images are acquired in cine mode and compared to the set of predicted images in real-time. The system performs geometric verification prior to dosimetric verification. When the measured image is acquired, the algorithm automatically detects the MLC leaf positions. A comparison between the leaf positions of the measured image and control points in the MLC file is made using the cosine similarity technique. The similarity index(SI) provides geometric MLC verification and synchronization between the measured and predicted images, as a uniform dose-rate cannot be assumed for IMRT or VMAT deliveries. The SI threshold was based on a series of experiments including 21 dynamic-IMRT fields defining pass/fail boundary(5 brain, 8 H & N, and 8 prostate cases).If geometric verification is successful, dosimetic verification is performed with the Gamma comparison(3%,3mm).The system reports the verification Result in real-time. Results: The system was simulated by MATLAB/SIMULINK and detected geometric and dosimetric errors during delivery. Both artificially introduced errors and clinical data were used for testing and analysis of the system performance. For a tested prostate field, the cumulative dose comparisons showed the minimum and maximum number of points with Gamma index < 1 as 93.5% and 98.5%, respectively. For individual dose comparisons on the same field, the values were 87% and 97%, respectively. Conclusion: This method includes automatic MLC leaf positioning, synchronization, and dosimetric verification. The pass/fail boundary of geometry was calculated based on the experiments. This system is a useful approach to detect unexpected possible errors occurring in the clinical setting and to prevent patient overdoses during radiotherapy especially in complex deliveries such as arc-IMRT. © 2012, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.4735840
Citations Scopus - 1
Co-authors John Oconnor
2012 King B, Greer P, 'TU-E-BRA-02: A Method to Remove Support Arm Backscatter from EPID Images.', Med Phys (2012)
DOI 10.1118/1.4735962
2011 Fuangrod T, O'Connor JD, McCurdy BMC, Greer PB, 'Development of EPID-based real time dose verification for dynamic IMRT', Proceedings of World Academy of Science, Engineering and Technology (2011) [E1]
Citations Scopus - 4
Co-authors John Oconnor
2011 Greer PB, Vial P, 'Epid dosimetry', Concepts and Trends in Medical Radiation Dosimetry: Proceedings of the SSD Summer School (2011) [E1]
DOI 10.1063/1.3576163
Citations Scopus - 8Web of Science - 6
2011 Lambert J, Dowling J, Menk F, Parker J, Capp A, Denham J, et al., 'SU-D-110-05: MR-Based Dose Calculation for Prostate Radiotherapy Using Atlas- Based Auto-Segmentation', Medical Physics (2011)

Purpose: A method that could enable dose calculations to be performed using magnetic resonance (MR) images for conventional treatment planning and adaptive planning using MR-accel... [more]

Purpose: A method that could enable dose calculations to be performed using magnetic resonance (MR) images for conventional treatment planning and adaptive planning using MR-accelerator systems would be to apply bulk electron densities to the MR images. However currently bone must be manually segmented making this impractical. This work develops and tests an atlas-based method to automatically segment bone on pelvic MR images for dose calculations. Methods: An MR whole-pelvic atlas was created using manually delineated scans from 39 patients. Atlas-based pelvic-bone auto-segmentations were then created for 25 patient scans using deformable image registration of the atlas to each patients scan with a leave-one-out atlas approach. These and corresponding expert manual segmentations were compared using the Dice similarity coefficient. Bone was assigned a density of 1.19 g/cm3 and all other tissues a water equivalent density. Treatment plans were generated on the whole-pelvis MR images and doses compared for the manual and auto-segmented bone plans. Results: The average Dice coefficient was 0.83 (standard deviation = 0.05). The average manual bone volume was 834.6 cm3 compared to the atlas based average volume of 840.0 cm3, with a mean difference of 5.4 cm3 (0.64%). The average ICRU point dose calculated on the MR images using the atlas-based bone segmentations was 0.2% lower (standard deviation 0.3%) than the dose calculated using the manual bone segmentations. Conclusions: The atlas based method for auto-segmentation of pelvic bone enables MR-based prostate radiotherapy dose calculations for treatment and adaptive planning. © 2011, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3611541
Co-authors Jim Denham, Fred Menk
2011 King B, Morf D, Greer P, 'SU-C-224-06: Investigation of a Modified Backscatter-Shielded EPID Dosimetry System for Improved IMRT Verification', Medical Physics (2011)

Purpose: To investigate the performance of a modified backscatter-shielded Electronic Portal Imaging Device (BS-EPID) system and to develop a model to convert the BS-EPID images t... [more]

Purpose: To investigate the performance of a modified backscatter-shielded Electronic Portal Imaging Device (BS-EPID) system and to develop a model to convert the BS-EPID images to water-equivalent dose. Methods: Images were acquired with a modified Varian aS-1000 BS-EPID and compared to those from a comparable clinical EPID. The asymmetry of in-plane profiles was examined as a measure of how well the system reduces the effect of the support arm backscatter. A new pixel-sensitivity correction method was assessed by comparing BS-EPID images of the same fields at different detector offset positions. A model was developed to determine the water equivalent dose from images acquired with the BS-EPID. The model converts the BS-EPID image to fluence using a deconvolution kernel, then to dose in water using a convolution kernel. The model was optimized based on experimental measurements and can be applied to construct dose in water at any depth. The validity of the model was tested using gamma analysis to compare 28 two-dimensional dose maps of IMRT fields measured with the BS-EPID at different depths to those predicted by the Eclipse TPS. Results: The BS-EPID profiles gave reduced asymmetry (0.6% compared to 3.3%), showing that the backscatter shielding is effective. BS-EPID images were consistent with different detector offsets within 0.4% on average. The IMRT dose maps measured with the BS-EPID gave good agreement with those predicted by the TPS, with mean values of 94.6%, 91.8%, 94.0% and 95.3% of pixels meeting the gamma criteria of 2%, 2mm at depths of 1.5, 5, 10 and 20 cm respectively. Conclusions: The BS-EPID performs effectively in reducing the effect of the backscatter from the support arm in Varian EPIDs. The BS-EPID dosimetry system and model allows high-resolution water equivalent doses to be measured with the BS-EPID, streamlining IMRT quality assurance. The authors have received support, in the form of equipment loans and technical information, from Varian Medical Systems iLab GmbH. © 2011, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3611454
2011 Dowling JA, Fripp J, Chandra S, Pluim JPW, Lambert JA, Parker J, et al., 'Fast automatic multi-atlas segmentation of the prostate from 3D MR images', International Workshop on Prostate Cancer Imaging: Image Analysis and Image-Guided Interventions Proceedings (LNCS 6963) (2011) [E1]
DOI 10.1007/978-3-642-23944-1_2
Citations Scopus - 23Web of Science - 20
Co-authors Jim Denham
2011 Rowshan Farzad P, Sabet M, McCowan P, McCurdy B, O'Connor JD, Greer PB, 'A new method for linear accelerator characterization for VMAT using Cine-EPID', Medical Physics (2011) [E3]
Co-authors John Oconnor
2011 Blake S, Vial P, Holloway L, Greer PB, Kuncic Z, 'An investigation into optical photon transport effects on electronic portal imaging performance using Geant4', Medical Physics (2011) [E3]
2011 King BR, Morf D, Greer PB, 'Investigation of a modified backscatter-shielded EPID dosimetry system for improved IMRT verification', Medical Physics (2011) [E3]
2011 Lambert JA, Dowling J, Menk FW, Parker J, Capp A, Denham J, et al., 'MR-based dose calculation for prostate radiotherapy using atlas-based auto-segmentation', Medical Physics (2011) [E3]
Co-authors Jim Denham, Fred Menk
2011 McCowan P, Rickey D, Rowshan Farzad P, Ansbacher W, Greer PB, McCurdy B, 'Precise gantry angle determination for EPID images during rotational IMRT', Medical Physics (2011) [E3]
2011 Mccowan P, Rickey D, Rowshanfarzad P, Ansbacher W, Greer P, Mccurdy B, 'SU-E-T-210: Precise Gantry Angle Determination for EPID Images during Rotational IMRT', Medical Physics (2011)

Purpose: Utilization of an aSi EPID to develop an in vivo patient dose verification system for rotational IMRT (rIMRT) delivery requires accurate knowledge of gantry angle as a fu... [more]

Purpose: Utilization of an aSi EPID to develop an in vivo patient dose verification system for rotational IMRT (rIMRT) delivery requires accurate knowledge of gantry angle as a function of time. Currently the accuracy of the gantry angle stamp in the header of the EPID image is limited to approximately +/-3 degrees. This work investigates several unique methods for a more accurate determination of the gantry angle during rIMRT. Methods: Gantry angles were determined using: (1) an incremental rotary encoder attached to the rotational axis of the gantry, (2) a direct analogue-to-digital measurement of the gantry potentiometer, and (3) through EPID image analyses of an in-house phantom (manufactured at sub-millimeter precision). The phantom consists of a cylindrical acrylic frame with one wire wrapped helically around its surface and one straight wire traversing its central axis. This design creates EPID images with unique and identifiable wire intersection points as a function of gantry orientation. Analysis of the treatment console log files was compared to the above methods. Results: The gantry potentiometer is considered the most accurate gantry angle but is unavailable during treatment. The ClinacLog produced discrepancies of up to ±2 degrees, the DynaLog up to ±1 degrees, and the encoder up to ±0.5 degrees with respect to the potentiometer. Preliminary analysis comparing our phantom-determined gantry angles with the encoder gantry angles showed agreement within ±0.5 degrees of each other for 85% of the data and differed at most by 1.3 degrees from each other. Conclusions: We have developed several techniques to determine gantry angle as a function of time during rIMRT. We have shown a strong agreement in gantry determination by our phantom and encoder. This investigation of gantry angle is critical to develop an accurate in vivo patient dose verification system for rIMRT delivery. © 2011, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3612160
Citations Scopus - 3
2011 Blake S, Vial P, Holloway L, Greer P, Kuncic Z, 'SU-F-BRA-02: An Investigation Into Optical Photon Transport Effects on Electronic Portal Imaging Performance Using Geant4', Medical Physics (2011)

Purpose: To develop a comprehensive Monte Carlo (MC) model of an indirect-detection electronic portal imaging device (EPID) that can self-consistently quantify the effect of optic... [more]

Purpose: To develop a comprehensive Monte Carlo (MC) model of an indirect-detection electronic portal imaging device (EPID) that can self-consistently quantify the effect of optical blur on the output signal. Methods: A model of an indirect-detection EPID was developed using the Geant4 MC toolkit. The EPID was modeled as a series of uniform slabs with thicknesses and material properties obtained from published literature. The model also included a slab of solid water backscatter material directly beyond the EPID rear housing. The standard electromagnetic and optical physics Geant4 modules were incorporated into the model to simultaneously simulate both high energy and optical photon transport relevant for indirect-detection EPIDs. A narrow, monoenergetic beam of 1 MeV photons was used to generate a line of radiation normally incident on the EPID surface. The beam width was equal to the pixel pitch of 0.4 mm used for scoring particle hits and energy deposition in the gadolinium oxysulfide scintillator and amorphous silicon photodiode layers. Optical and gamma photons were scored separately in the photodiode layer to measure their relative effects on the output signal. Line spread functions (LSFs) were generated indicating the distribution of hits and energy deposited across the scintillator and photodiode planes. Results: The LSFs for optical photon hits in the photodiode array and energy deposition events in the scintillator had a FWHM of approximately 4.7 mm and 0.82 mm, respectively. This indicates a significant increase in image blurring due to optical photon scatter. Conclusions: Our results indicate that modeling optical photon transport may be important when simulating imager performance for an indirect-detection EPID. Further analysis of calculated LSFs, including determination of the detector modulation transfer function, is required to further quantify imager performance. Cancer Council NSW Research Project Grant RG 11-06 Cancer Institute NSW Research Equipment Grant 10/REG/1-20. © 2011, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3612869
2011 Chytyk K, Van Uytven E, Van Beek T, Greer P, Mccurdy B, 'SU-E-T-205: Physical Model for in Vivo Dose Image Prediction', Medical Physics (2011)

Purpose: To create a physical fluence model for portal dose image prediction that will be used to verify patient radiation treatment delivery. Methods and Materials: A physical fl... [more]

Purpose: To create a physical fluence model for portal dose image prediction that will be used to verify patient radiation treatment delivery. Methods and Materials: A physical fluence model was created to predict portal dose images. This model utilized Monte Carlo simulation and linac-specific engineering schematics of the MLCs to create as accurate a model as possible. The fluence model consists of a focal and extra-focal source, determined to be a Gaussian and Gaussian-like function, respectively. The MLC transmission is calculated by attenuating a pre-MLC BEAMnrc spectrum through the leaves; the MLC leaf-tip and tongue-and-groove are modeled using the schematics. Incident energy fluence profiles from BEAMnrc are used to account for the field shape and beam horns. The asymmetric backscatter from the EPID arm is also modeled. The energy fluence is converted to dose using a superposition of EPID-specific dose kernels. Scatter from the patient or phantom is approximated using Monte Carlo calculated scatter fluence kernels. The model is tested on simple slab phantoms for a variety of field sizes, thicknesses and air gaps. It was also tested on one field acquired during a patient's prostate IMRT treatment. Results: Predicted images with phantoms in the beam agreed within 2%, 2 mm in relative comparison with the measured images. After calibration of measured and predicted images to absolute units, the images agreed within 3% and 3 mm. The patient IMRT field predicted image was not ideal when compared to the measured image, mainly because the patient is heterogeneous. Conclusions: The physical fluence model, in conjunction with the patient scatter model, is accurate and could be used to verify patient treatment. The algorithm is versatile and can be applied to a variety of treatment scenarios. © 2011, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3612155
2011 Rowshanfarzad P, Sabet M, Mccowan P, Mccurdy B, O''connor D, Greer PB, 'MO-F-214-08: A New Method for Linear Accelerator Characterization for VMAT Using Cine-EPID', Medical Physics (2011) [C3]

Purpose: A cine-EPID based method to separately measure the mechanical motion characteristics of gantry, jaws and multi-leaf collimator as a function of gantry angle during VMAT h... [more]

Purpose: A cine-EPID based method to separately measure the mechanical motion characteristics of gantry, jaws and multi-leaf collimator as a function of gantry angle during VMAT has been developed. Methods: Irradiations were performed using 6 MV beams of a Varian Trilogy linear accelerator with an aS1000 EPID. Images were acquired using 360 MU irradiations at 600 MU/min in cine acquisition mode at 2 Hz frame-rate. To establish the gantry isocentre, a Winston-Lutz technique was used with a circular collimator rigidly attached to the gantry head. The displacement of the centre of a fixed tungsten ball at isocentre from the field centre was determined on each image with a sub-pixel thresholding technique. EPID coordinates were transformed to room coordinates. Jaw and MLC sag relative to the gantry head were determined from the displacement of a gantry-mounted tungsten ball relative to static jaw and MLC positions. MLC speed constancy was determined by segmenting MLC positions on each image for a constant leaf-speed test pattern. Gantry speed constancy was assessed with an independent liquid-based inclinometer and the linac gantry angle potentiometer. Results: The gantry isocentre was ~ 1 mm amplitude with changes in isocentre occuring over time suggesting frequent measurement is required. Jaw sag was found to be very small ~ 0.2 mm amplitude, with MLC sag ~ 0.6 mm. Average leaf speed was found to be consistent for the MLC leaves however the variation in speed varied systematically across the leaf bank which requires further investigation. Gantry speed was consistent although the inclinometer was found to lag ~ 2 degrees in reading from the potentiometer. Conclusions: The cine-EPID based method quantifies the mechanical motion characteristics of the linac as a function of gantry angle during arc-therapy with improved precision and efficiency of quality assurance over previous methods. © 2011, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3613021
Co-authors John Oconnor
2010 Vial P, Kunic Z, Gustafsson H, Oliver L, Sabet M, Baldock C, Greer PB, 'Developing a next generation detector for radiotherapy treatment verification', Sydney Cancer Conference 2010. Profiling Risk, Personalising Treatment and Predicting Outcomes. Conference Program and Abstract Book (2010) [E3]
2010 Dowling J, Lambert J, Parker J, Fripp J, Denham JW, Wratten C, et al., 'Sci¿Sat AM(1): Planning ¿ 05: Feasibility of Atlas-Based Organ Segmentation and Electron Density Mapping for MRI-Based Prostate Radiation Therapy Planning', Medical Physics (2010)

This project develops atlas-based deformable image registration methods to map electron densities and automatically segment organs on MRI scans. This will enable dose calculations... [more]

This project develops atlas-based deformable image registration methods to map electron densities and automatically segment organs on MRI scans. This will enable dose calculations to be performed using the MRI scan without the requirement for an additional CT scan. The method developed uses atlas-based deformable image registration. An MRI atlas was developed based on whole pelvic MRI scans for 39 patients. The atlas is then registered to an individual patient MRI scan. The registration of the atlas organ contours gives the automatically segmented organs on that patient scan. A CT or electron-density atlas was also developed that corresponds to the MRI atlas. The deformation vectors that register the MRI-atlas to the patient MRI scan are applied to the CT-atlas to produce a pseudo-CT scan for the patient. This can then be used for dose planning and digitally reconstructed radiographs. The feasibility of the entire workflow has been tested for one patient. The rectum, bladder, prostate and bone were automatically segmented on the MRI scan with Dice coefficient results of 0.82, 0.59, 0.62 and 0.81. The patient's plan was applied to the pseudo-CT using a commercial treatment planning system. Dose at the normalisation point was 2.9% lower than on the full density CT plan. This method will improve the workflow of prostate radiotherapy planning and will reduce systematic uncertainties introduced by MRI-CT registration. © 2010, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3476205
Citations Scopus - 1
Co-authors Jim Denham
2010 Sabet M, Vial P, Menk FW, Denham JW, Greer PB, 'Sci¿Sat AM(2): Brachy ¿ 08: Evaluation of an A-Si EPID in Direct Detection Configuration for Transit Dosimetry in Radiotherapy', Medical Physics (2010)

The accuracy of dosimetry measurements using a-Si EPIDs is affected by their structural characteristics particularly due to the presence of the Gd 2 O 2 S phosphor layer. Our prev... [more]

The accuracy of dosimetry measurements using a-Si EPIDs is affected by their structural characteristics particularly due to the presence of the Gd 2 O 2 S phosphor layer. Our previous measurements have shown that modification of the structure to direct detection configuration by removal of the phosphor layer can improve the imager properties for transit dosimetry applications. In this study a research dedicated Varian a-Si EPID has been changed to direct detection configuration and evaluated for transit dosimetry measurements using 7 prostate and 9 IMRT fields with a 20 cm thick phantom in the beam by comparison to a MatriXX detector array. The EPID images were converted to dose using a calibrated 0.6 cc ionization chamber. Gamma evaluation (3%, 3 mm criteria) of the results for for all points greater than 10% of the maximum dose showed that the fraction of points with a Gamma index less than 1 was at least 94.6% in head and neck fields and 99.3% in prostate fields. The mean Gamma was 0.360 and 0.288 for head and neck and prostate fields, respectively. In conclusion, The EPID results are very close to the reference dosimeter and the direct EPID appears to be a promising device for online patient dosimetry applications for the future. © 2010, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3476220
Co-authors Jim Denham, Fred Menk
2010 Dowling J, Lambert JA, Parker J, Greer PB, Fripp J, Denham J, et al., 'Automatic MRI atlas-based external beam radiation therapy treatment planning for prostate cancer', Prostate Cancer Imaging: Computer-Aided Diagnosis, Prognosis, and Intervention International Workshop, Held in Conjunction with MICCAI 2010, Beijing,China, September 24, 2010. Proceedings (2010) [E1]
Citations Scopus - 14Web of Science - 11
Co-authors Jim Denham
2010 Mccowan PM, Mccurdy BM, Greer PB, Rickey DW, Rowshanfarzad P, 'Poster ¿ Thur Eve ¿ 51: An Investigation of Geometry Issues for EPID Dosimetry during Rotational IMRT', Medical Physics (2010)

INTRODUCTION: Amorphous-silicon electronic portal imaging devices (EPIDs) have been established as useful tools for dosimetry. To accurately reconstruct the patient dose delivered... [more]

INTRODUCTION: Amorphous-silicon electronic portal imaging devices (EPIDs) have been established as useful tools for dosimetry. To accurately reconstruct the patient dose delivered during rotational IMRT, one must acquire time-resolved EPID images as a function of gantry-angle. Dose reconstruction accuracy is directly impacted by the accuracy of the geometry of the imaging system, including the gantry-angle readout (i.e. source geometry) and the EPID support-arm sag (i.e. imager geometry). This work investigates these two factors. METHODS: The EPID support-arm sag was investigated through measurements performed on Varian E-arm and R-arm models at two institutes and employing two different analysis methods. One method imaged an isocentric ball-bearing whose position was tracked over all gantry-angles. The second method involved analysing field edges to obtain the field centre location of all images. Gantry-angle accuracy was examined by comparing the gantry-angle indicated at the treatment console readout to the gantry-angle written to the EPID DICOM header. We developed a method of measuring gantry-angle directly from the gantry-angle potentiometer. RESULTS: The E-arm showed maximum displacement of roughly 0.6mm (cross-plane) and 0.8mm (in-plane). R-arm results were significantly worse, estimated at 8.5mm (cross-plane) and 5.0mm (in-plane). Gantry-angle analysis demonstrated approximately 2 degrees of uncertainty in the gantry-angle contained in the EPID image. A direct measurement of the gantry angle potentiometer was demonstrated. CONCLUSIONS: Two main factors affecting patient dose reconstruction using EPID dosimetry have been investigated. EPID support-arm sag can be measured (and corrected). Near real-time gantry-angle measurement can be performed through directly monitoring the potentiometer signal. © 2010, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3476156
Citations Scopus - 2
2010 Rowshanfarzad P, Sabet M, O'connor DJ, Greer PB, 'Sci¿Sat AM(2): Brachy ¿ 07: Amelioration of the Effect of Non-Uniform Arm Backscatter on Dosimetry with a Varian A-Si EPID', Medical Physics (2010)

The backscattered radiation from the support arm of Varian a-Si EPIDs can affect the accuracy of dosimetric measurements using these devices. In this study the effect of insertion... [more]

The backscattered radiation from the support arm of Varian a-Si EPIDs can affect the accuracy of dosimetric measurements using these devices. In this study the effect of insertion of lead sheets between the EPID and the arm has been investigated for the E-type arms. The optimum lead thickness was determined by comparison of the imager response on and off the arm with increasing lead thicknesses and 2 mm of lead was selected as the optimal thickness considering the reasonable extra weight added to the imager. It reduced the arm backscatter from a maximum of about 6% and 3.5% higher than the off-arm signal in 6 MV and 18 MV beams to about 2% for both energies. On-axis EPID response measurements for different field sizes showed a considerable decrease in arm backscatter with the addition of lead. The symmetry improved for the largest field from about 105% and 103% to 101% and 100% using 2 mm lead. Changing the SDD did not affect the backscatter component more than 1%. The addition of lead decreased the contrast-to-noise ratio and resolution by 1.3% and 0.8% for 6 MV and by 0.5% and 0.4% for 18 MV beams. The root mean square deviation for the difference in EPID central pixel position with and without lead during a whole gantry rotation was one pixel at maximum. In conclusion a 2 mm thick lead layer seems sufficient for acceptable dosimetry results with no major degradation to the routine performance of the imager. © 2010, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3476219
Co-authors John Oconnor
2009 Hatton J, Capp A, Gupta S, Tang C, Wright P, Greer PB, 'Assessment of dose delivered during prostate radiotherapy using cone beam CT scans for adaptive radiotherapy', Journal of Medical Imaging and Radiation Oncology (2009) [E3]
Co-authors Joan Hatton
2009 Gustafsson H, Vial P, Kuncic Z, Baldock C, Denham J, Greer PB, 'Intensity modulated radiation therapy verification with a novel modified EPID design', Journal of Medical Imaging and Radiation Oncology (2009) [E3]
Co-authors Jim Denham
2009 Rowshan Farzad P, Sabet M, McCurdy BMC, O'Connor JD, Greer PB, 'A measurement-based model for backscatter from an a-Si EPID support arm to improve IMRT dose verification', Journal of Medical Imaging and Radiation Oncology (2009) [E3]
Co-authors John Oconnor
2009 Dowling J, Neubert A, Fripp J, Bourgeat P, Patterson J, Denham J, et al., 'Atlas-based, automatic segmentation of the pelvis for prostate radiotherapy planning', Journal of Medical Imaging and Radiation Oncology (2009) [E3]
DOI 10.1111/j.1440-1673.2009.01207.x
Co-authors Jim Denham
2009 Sabet M, Menk FW, Greer PB, 'Evaluation of a modified amorphous silicon electronic portal imaging device for transit dosimetry', Journal of Medical Imaging and Radiation Oncology (2009) [E3]
DOI 10.1111/j.1440-1673.2009.01207.x
Co-authors Fred Menk
2009 Sabet M, Menk FW, Greer PB, 'Investigation of the effect of dose rate variations on response of an a-Si EPID in clinical and modified configurations', Journal of Medical Imaging and Radiation Oncology (2009) [E3]
DOI 10.1111/j.1440-1673.2009.01211.x
Co-authors Fred Menk
2009 Dowling J, Bourgeat P, Raffelt D, Fripp J, Greer PB, Patterson J, et al., 'Non-rigid correction of interleaving artefacts in pelvic MRI', Medical Imaging 2009: Image Processing (2009) [E1]
DOI 10.1117/12.812460
Citations Scopus - 5
Co-authors Jim Denham, Peter Stanwell
2009 McCurdy BMC, Greer PB, 'Dosimetric properties of an EPID for real-time dose verification', Medical Physics (2009) [E3]
2009 Mccurdy B, Greer PB, 'Sci¿Wed PM: Delivery¿11: Dosimetric Properties of an EPID for Real-Time Dose Verification', Medical Physics (2009)

PURPOSE: Dosimetric properties of an amorphous-silicon electronic portal imaging device (EPID) operated in a real-time acquisition mode were investigated. This mode will be essent... [more]

PURPOSE: Dosimetric properties of an amorphous-silicon electronic portal imaging device (EPID) operated in a real-time acquisition mode were investigated. This mode will be essential for time-resolved dose verification of dynamic-IMRT and arc-IMRT. METHODS: The EPID was used in continuous acquisition mode, where individual sequential image frames are acquired in real-time. Properties studied include dose linearity and reproducibility. Summed continuous acquisition mode results were also compared to dose results using the well-studied integrated acquisition mode, for example treatment deliveries including dynamic-IMRT and single-arc-IMRT. Comparison was made using percentage dose difference of in-field pixels (pixels > 10% of maximum signal). Temporally-resolved EPID response was also compared to that of ion-chamber data for selected points in the deliveries. RESULTS: Using continuous acquisition mode, EPID response was not linear with dose, with response approximately corresponding to 1¿1.5 missed images per irradiation. Reproducibility of EPID response improved with increasing MU. Analysis of the example irradiations revealed summed continuous acquisition mode compared well to integrated acquisition mode, within 2% of maximum dose for more than 95% of in-field pixels. Time resolved EPID data compared well to ion chamber data, with dose increases/decreases overlying each other. CONCLUSION: Continuous acquisition mode is suited for time-resolved dosimetry applications including single-arc-IMRT and dynamic IMRT, giving comparable dose results to the integrated acquisition mode. Linearity and reproducibility should be adequate for clinical applications although caution should be used in low MU work. Time-resolved EPID dose information also compared well to time-resolved ion-chamber measurements. © 2009, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.3244103
2008 Lee CG, Greer PB, Menk FW, 'The effect of non-uniform backscatter on EPID dosimetry', EPSM ABEC 2008: Innovations in Patient Care: Conference Handbook (2008) [E3]
Co-authors Fred Menk
2008 Lambert JA, Greer PB, Patterson J, Dowling J, Salvado O, Menk FW, 'Bulk electron density treatment planning for MRI-based prostate radiotherapy', EPSM ABEC 2008: Innovations in Patient Care: Conference Handbook (2008) [E3]
Co-authors Fred Menk
2008 Vial P, Greer PB, Lee CG, Gustafsson H, Oliver L, Baldock C, 'Contributing factors in the field size response of an EPID', EPSM ABEC 2008: Innovations in Patient Care: Conference Handbook (2008) [E3]
2008 Hatton J, Greer PB, 'Evaluation of cone beam CT data for dose calculation in adaptive planning', EPSM ABEC 2008: Innovations in Patient Care: Conference Handbook (2008) [E3]
Co-authors Joan Hatton
2008 Wang S, Gordon JJ, Greer P, Li W, Siebers J, 'MO-E-332-06: Monte Carlo-Based EPID Dose Kernels Accounting for Variations in Field Size Response', Medical Physics (2008)

Purpose: To create a series of EPID Monte Carlo dose computation kernels which accounts for observed machine-to-machine variations in EPID response. Method and Materials: Field si... [more]

Purpose: To create a series of EPID Monte Carlo dose computation kernels which accounts for observed machine-to-machine variations in EPID response. Method and Materials: Field size response of aS500 and aS1000 imagers are measured for several Varian Cl21-series machines that were dosimetrically matched in a water phantom. Deviations in imager response are attributed to differences in back-scattering materials beneath the imaging panels. Mono-energetic convolution kernels with various backscatter thicknesses are simultaneously created by sub-dividing a thick back-scattering slab into multiple sub-slabs and using the EGSnrc LATCH bit to score sub-slab kernel contributions. Energy-binned particle fluence incident upon the detector convolved with the imager-specific kernels are used to compute the EPID image. Imager-specific kernels are determined by matching computed and measured EPID field-size response, using the number of sub-slabs as a free parameter. Final kernels are used for Monte Carlo-based pre-treatment and in-treatment EPID dose computations. Results: The EPID imagers on dosimetrically matched accelerators are found to differ. Most, but not all of the deviations appear to be correlated with the imager mounting arm type. The imager-specific kernels matched the field-size response for each imager within 1%, and resulted in dosimetric agreement between measured and computed images for pre-treatment dosimetric verification of IMRT fields. Conclusion: Dosimetric differences between portal imagers on matched accelerators can be accounted for by using computation kernels with differing amounts of back-scattering materials. Kernels for multiple different back-scattering thickness can be efficiently calculated. Resultant imager-specific kernels may be useful for efficient pre-treatment and in-treatment Monte Carlo-based EPID dose computations. Conflict of Interest: This work was funded in part by Varian Medical Systems. © 2008, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.2962405
2008 Greer P, Cadman P, Bzdusek K, 'SU-GG-T-129: A High Resolution Fluence-Convolution Model for Prediction of Amorphous Silicon EPID IMRT Images', Medical Physics (2008)

In this work an amorphous silicon electronic portal imaging device (a-Si EPID) dose prediction model based on the fluence model of the Pinnacle treatment planning system Version 7... [more]

In this work an amorphous silicon electronic portal imaging device (a-Si EPID) dose prediction model based on the fluence model of the Pinnacle treatment planning system Version 7 (Philips Medical Systems, Madison, WI, USA) is developed. A fluence matrix at very high resolution (0.5 mm) is used to incorporate multileaf collimator (MLC) leaf transmission effects in the predicted EPID images. The primary dose deposited in the EPID is calculated from the fluence using experimentally derived radially dependent EPID interaction coefficients for the open and MLC transmitted fluence components. A spatially invariant EPID dose deposition kernel that describes both radiative dose deposition and optical scatter is convolved with the primary dose. The kernel is further optimised to give accurate EPID scatter factor with changing MLC field size. Model predictions were compared to a-Si EPID images corrected for pixel sensitivity variation, support-arm backscatter and calibrated to dose for various static jaw defined and MLC defined fields and a step and shoot intensity modulated radiotherapy (IMRT) field. For the static fields the model predicts EPID off-axis ratio, penumbral shape as well as inter-leaf leakage. For the IMRT field with a Gamma criteria of 2% and 2 mm, 97.2% of points had a Gamma index less than 1. We found that incorporating the difference in EPID response to open and MLC transmission did not improve the accuracy of the prediction for the IMRT field. The developed model incorporates the effects of MLC design on the dose and therefore should improve the verification of IMRT treatments with EPIDs. © 2008, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.2961881
2008 Vial P, Hunt P, Greer P, Oliver L, Baldock C, 'SU-GG-T-130: A Software Tool for IMRT and EPI Dosimetry Research', Medical Physics (2008)

Purpose: To develop a software tool for intensity modulated radiotherapy (IMRT) and electronic portal imaging (EPI) dosimetry research. The software tool implements correction fac... [more]

Purpose: To develop a software tool for intensity modulated radiotherapy (IMRT) and electronic portal imaging (EPI) dosimetry research. The software tool implements correction factors to a commercially available EPI dosimetry model to account for the change in EPI response to multileaf collimator (MLC) transmitted beam as compared to open beam in IMRT fields. Method and Materials: Software was designed to perform the following tasks: i) Read MLC files from IMRT treatment plans and calculate a matrix of open beam and MLC transmission components. ii) Read portal dose image prediction (PDIP) files exported from the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA). iii) Interpolate correction factors from look-up tables for each PDIP based on the MLC transmission components of the corresponding MLC file. iv) Calculate and write a corrected PDIP that can be imported back into the planning system. The software tool was developed using the Microsoft Visual Studio.NET framework with the C¿ compiler. The software tool was validated for functionality and accuracy with a series of test IMRT fields. Results: The software tool correctly calculated the open and MLC beam components for different MLC models and collimator rotations. The corrected PDIP pixel values agreed with manual calculations to within 1% in all cases. Artifacts in the corrected PDIP in regions of high dose gradients were avoided when the MLC transmission matrix was sampled with pixel size ¿ PDIP pixel size. Additional functions available with the software tool include the ability to write the open beam matrix to file, perform arithmetic operations on images, display and save image files, and to plot profile comparisons across images and open beam matrices. Conclusion: A software tool was developed and validated for IMRT and EPI dosimetry investigations. The software tool is being developed further for EPI dosimetry using transit IMRT beams. © 2008, American Association of Physicists in Medicine. All rights reserved.

DOI 10.1118/1.2961882
2008 Vial P, Hunt P, Greer P, Oliver L, Baldock C, 'Proceedings of Student Research Symposium of the ACT/NSW Branch of the Australasian College of Physical Scientists and Engineering in Medicine Friday 7 December 2007 Slade Lecture Theatre Institute of Medical Physics School of Physics University of Sydney', AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE (2008) [C1]
2007 Denham J, Joseph D, Lamb D, Tai KH, Turner S, Matthews J, et al., 'Reasons for initial PSA (iPSA) and biochemical failure (BF) being poor predictors of prostate cancer (PC) mortality', European Journal of Cancer Supplements (ECCO 14 Abstract Book) (2007) [E3]
DOI 10.1016/s1359-6349(07)71071-6
Co-authors Allison Steigler, Jim Denham
2007 Clews L, Greer PB, 'Linear accelerator quality assurance with an a-Si EPID', Australasian Physical and Engineering Sciences in Medicine (2007) [E3]
2007 Hatton J, Tehovnik T, Greer PB, 'Investigation of an objective comparison of measured and calculated profiles using dose and distance to agreement', Australasian Physical and Engineering Sciences in Medicine (2007) [E3]
2007 Greer PB, Cadman P, Bzdusek K, 'A Fluence-convolution model for prediction of amorphous silicon EPID IMRT images', Australasian Physical and Engineering Sciences in Medicine (2007) [E3]
2007 Tehovnik T, Greer PB, Carolan M, Ansbacher W, Metcalfe P, 'Three dimensional dose verification for IMRT using amorphous silicon EPIDS', Australasian Physical and Engineering Sciences in Medicine (2007) [E3]
2007 Vial P, Hunt P, Greer PB, Oliver L, Baldock C, 'A comparison of portal dosimetry and dose to water measurements of IMRT beams', Australasian Physical and Engineering Sciences in Medicine (2007) [E3]
2007 Ebert MA, Lambert JA, Greer PB, 'CT-number dependence on KV/MA settings - Influence of auto-mA', EPSM-ABEC 2007. Australasian Physical and Engineering Sciences in Medicine. Proceedings (2007) [E3]
2007 Popescu C, Greer P, 'Eclipse AAA versus pinnacle dose prediction for transit dosimetry: Comparison with Monte Carlo', RADIOTHERAPY AND ONCOLOGY (2007)
2007 Greer PB, Clews L, 'Comprehensive linear accelerator quality assurance with an A-SI EPID', Radiotherapy & Oncology (2007) [E3]
2007 Popescu C, Greer PB, 'Eclipse AAA Vs Pinnacle dose prediction for transit dosimetry: Comparison with Monte Carlo', Radiotherapy & Oncology (2007) [E3]
2007 Lee C, Greer PB, Cadman P, 'A simple approach to using the AS500 amorphous silicon EPID to verify IMRT fields', Radiotherapy & Oncology (2007) [E3]
2006 Greer PB, Dahl K, Ostwald PM, Denham J, Lau P, Hughes C, White M, 'An investigation of MRI dose planning for high precision prostate radiotherapy', Australasian Physical & Engineering Sciences in Medicine (2006) [E3]
Co-authors Patricia Ostwald, Jim Denham
2006 Greer PB, Dahl K, Ostwald PM, Pichler P, Denham J, Wratten C, White M, 'Initial clinical experience with implanted fiducial guided prostate radiotherapy', Australasian Physical & Engineering Sciences in Medicine (2006) [E3]
Co-authors Patricia Ostwald, Jim Denham
2006 Lee CG, Greer PB, Menk FW, 'Determination of optimal depth in water for comparison of planning system dose maps and EPID images', Australasian Physical & Engineering Sciences in Medicine (2006) [E3]
Co-authors Fred Menk
2006 Joseph D, Lamb D, Denham J, Tai K-H, Turner S, Matthews J, et al., 'The biological significance of longitudinal changes in PSA; Post treatment variation sand mistaken biochemical failure.', RADIOTHERAPY AND ONCOLOGY (2006)
Co-authors Allison Steigler, Jim Denham
2006 Denham J, Joseph D, Lamb D, Tai K-H, Turner S, Matthews J, et al., 'The biological significance of longitudinal changes in PSA; Doubling time during biochemical failure', RADIOTHERAPY AND ONCOLOGY (2006)
Co-authors Jim Denham, Allison Steigler
2006 Haworth A, Joseph D, Lamb D, Duchesne G, Kearvell R, Hooton B, et al., 'Quality control studies for radiation delivery in a multicentre prostate cancer clinical trial', RADIOTHERAPY AND ONCOLOGY (2006)
Co-authors Jim Denham
2006 Lamb D, Denham J, Joseph D, Tai K, Turner S, Matthews J, et al., 'The biological significance of longitudinal changes in PSA; Post treatment variations and mistaken biochemical failure', INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS (2006)
DOI 10.1016/j.ijrobp.2006.07.632
Co-authors Jim Denham, Allison Steigler
2006 Denham J, Joseph D, Lamb D, Tai K, Turner S, Matthews J, et al., 'The biological significance of longitudinal changes in PSA; Doubling time during biochemical failure', Proceedings of the 48th Annual Meeting of the American Society for Therapeutic Radiology and Oncology, 48th Annual Meeting of the American Society for Therapeutic Radiology and Oncology (2006) [E3]
Co-authors Jim Denham, Allison Steigler
2006 Greer PB, 'Preliminary investigaton of the effect of a-Si EPID spectral response on IMRT dosimetry', EPI2K6: Programme and Abstracts (2006) [E3]
2006 Greer PB, Cadman P, Bzdusek K, Carolan M, 'A fluence-convolution model for prediction of dosimetric EPID images incorporating off-axis spectral response', EPI2K6: Programme and Abstracts (2006) [E3]
2006 Haworth A, Kearvell R, Price S, Greer PB, Baily M, Hooton B, et al., 'The radar set-up accuracy study', EPI2K6: Programme and Abstracts (2006) [E3]
Co-authors Jim Denham
2006 Kenny J, Greer PB, Ebert MA, 'Generation of low kV portal images from a linear accelerator with an aSi EPID and an external imaging target', EPI2K6: Programme and Abstracts (2006) [E3]
2005 Dempsey CL, Greer PB, 'Verification of step-and-shoot breast compensator IMRT fields with an amorphous silicon EPID', Radiotherapy & Oncology (2005) [E3]
Co-authors Claire Dempsey
2005 Greer PB, 'The off-axis response of an amorphous silicon electronic portal imaging device', Radiotherapy & Oncology (2005) [E3]
2005 Greer PB, Barnes M, 'The two-dimensional dosimetric stability of the aS500 amorphous silicon EPID for measurement of absolute dose and beam profiles', Radiotherapy & Oncology (2005) [E3]
2005 Greer PB, Barnes M, 'Assessment of the aS500 amorphous silicon EPID for measurement of enhanced dynamic wedge', Radiotherapy & Oncology (2005) [E3]
2005 Ebrahimpour H, Greer PB, Ebert MA, Ourselin S, Popescu D, 'Evaluation of Art and Feildkamp Algorithms for Megavoltage CT', EPSM 2005 Conference Handbook (2005) [E3]
2004 Greer PB, 'Prediction of transmitted portal dose for in-vivo dosimetry by a superposition-convolution planning system', Conference Handbook (2004) [E3]
2004 Greer PB, 'An investigation of dose and beam profile dosimetry with an amorphous silicon epid', Conference Handbook (2004) [E3]
2004 Greer PB, Kenny J, 'Implementation of virtual simulation with a side-bore multislice helical CT scanner', Conference Handbook (2004) [E3]
2004 Kenny J, Ebert MA, Greer PB, 'Generation of low KV X-ray portal images with mega-voltage electron beams', Conference Handbook (2004) [E3]
2004 Greer PB, 'Assessment of an amorphous silicon epid for quality assurance of enhanced dynamic wedge', Conference handbook (2004) [E3]
2004 Greer PB, 'On-line imaging during treatment', Program and Abstract Book (2004) [E3]
2003 Greer PB, Chaney J, Bremner L, Graham C, 'Comparison of Inter-Observer Variability in Portal Image Registration with Single and Double-Exposure Images', CD-Rom (2003) [E3]
2002 Popescu C, Greer P, Wells D, 'Use of an amorphous silicon electronic portal imaging device for dynamic multileaf collimator quality assurance', MEDICAL PHYSICS (2002)
Citations Web of Science - 1
Show 115 more conferences

Other (1 outputs)

Year Citation Altmetrics Link
2016 Lehmann J, Miri N, Legge K, Greer P, 'Virtual EPID Standard Phantom Audit (VESPA) for remote IMRT and VMAT credentialing', (2016) [O1]
Citations Scopus - 1Web of Science - 1
Edit

Grants and Funding

Summary

Number of grants 47
Total funding $13,471,485

Click on a grant title below to expand the full details for that specific grant.


20181 grants / $210,045

The Australian MRI-Linac Program: Transforming the Science and Clinical Practice of Cancer Radiotherapy$210,045

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team Professor Paul Keall, Professor Michael Barton, Professor Stuart Crozier, Conjoint Professor Peter Greer
Scheme Program Grant
Role Lead
Funding Start 2018
Funding Finish 2022
GNo G1701287
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON Y

20172 grants / $792,823

Improving patient safety in radiation therapy with the Watchdog real-time treatment delivery verification system$602,815

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team Conjoint Professor Peter Greer, Professor Rick Middleton, Conjoint Associate Professor Jarad Martin, Dr Jeremy Booth, Dr Boyd McCurdy, Dr Dale Lovelock, Dr Andrew Kneebone
Scheme Project Grant
Role Lead
Funding Start 2017
Funding Finish 2020
GNo G1600453
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON Y

HMRI MRSP Cancer Research Program$190,008

Funding body: Hunter Medical Research Institute

Funding body Hunter Medical Research Institute
Project Team Conjoint Professor Stephen Ackland, Professor Xu Dong Zhang, Laureate Professor Rodney Scott, Doctor Nikki Verrills, Conjoint Associate Professor Jarad Martin, Doctor Steve Smith, Associate Professor Christine Paul, Conjoint Professor Peter Greer, Conjoint Associate Professor Anthony Proietto, Doctor Fiona Day, Associate Professor Christopher Scarlett
Scheme NSW MRSP Infrastructure Grant
Role Investigator
Funding Start 2017
Funding Finish 2017
GNo G1700603
Type Of Funding Other Public Sector - State
Category 2OPS
UON Y

20163 grants / $1,134,197

Reducing the greatest uncertainty in radiotherapy$594,197

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team

Holloway L, Haworth A, Dowling J, Ebert MA, Jameson M, Kron T, Vinod S, Leong T, Greer PB, Creutzberg C

Scheme Project Grant
Role Investigator
Funding Start 2016
Funding Finish 2016
GNo
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON N

A multistage multi centre international randomised trial of Conventional care Or Radioablation (CORE)$435,000

Funding body: Cancer Australia

Funding body Cancer Australia
Project Team

Faroudi F, Khoo V, Pryor D, Foote M, Ball D, Graham P, Martin J, Greer PB, Millwood M,

Scheme Priority-driven Collaborative Cancer Research Scheme
Role Investigator
Funding Start 2016
Funding Finish 2016
GNo
Type Of Funding Aust Competitive - Non Commonwealth
Category 1NS
UON N

The accuracy and utility of Intra-fraction Motion Review (IMR) in clinical practice using the Truebeam STx$105,000

Funding body: Varian Medical Systems, Inc.

Funding body Varian Medical Systems, Inc.
Project Team

Simpson J, Greer PB, Lehmann J

Scheme Research Grant
Role Investigator
Funding Start 2016
Funding Finish 2016
GNo
Type Of Funding International - Competitive
Category 3IFA
UON N

20154 grants / $637,000

Improving cancer imaging and targeted radiotherapy using audiovisual biofeedback$588,000

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team

Keall P, Kay, J, O’Brien R, Kron T, Greer PB, Hebblewhite M, Sawant A

Scheme Development Grant
Role Investigator
Funding Start 2015
Funding Finish 2016
GNo
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON N

Radiotherapy treatment for prostate cancer - a change in practice based on direct evidence for targeting and toxicity effects using real outcomes data$24,000

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team Associate Professor Martin Ebert, Dr Jason Dowling, Conjoint Professor Jim Denham, Professor David Joseph, Dr Sarah Gulliford, Professor David Dearnaley, Associate Professor Annette Haworth, Dr Lois Holloway, Professor Tomas Kron, Conjoint Professor Peter Greer
Scheme Project Grant
Role Investigator
Funding Start 2015
Funding Finish 2017
GNo G1401429
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON Y

VESPA$15,000

Funding body: Calvary Mater Newcastle

Funding body Calvary Mater Newcastle
Project Team Conjoint Professor Peter Greer, Doctor John Holdsworth, Doctor Andrew Fleming, Dr Joerg Lehmann, Miss Narges Miri
Scheme Project Grant
Role Lead
Funding Start 2015
Funding Finish 2015
GNo G1500770
Type Of Funding Contract - Aust Non Government
Category 3AFC
UON Y

VESPA project$10,000

Funding body: TROG (Trans Tasman Radiation Oncology Group)

Funding body TROG (Trans Tasman Radiation Oncology Group)
Project Team Conjoint Professor Peter Greer, Doctor John Holdsworth, Doctor Andrew Fleming, Dr Joerg Lehmann
Scheme Research Grant
Role Lead
Funding Start 2015
Funding Finish 2015
GNo G1401525
Type Of Funding Grant - Aust Non Government
Category 3AFG
UON Y

20144 grants / $5,890,346

Renewing Intersects share of the national computing infrastructure$1,025,000

Funding body: ARC (Australian Research Council)

Funding body ARC (Australian Research Council)
Project Team

Hawkes, Evatt R; Yu, Aibing B; Ferry, Michael; Lewis, Geraint F; Muller, Dietmar; Wilkins, Marc R; Radom

Scheme Linkage Projects
Role Investigator
Funding Start 2014
Funding Finish 2016
GNo
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON N

Renewing Intersect's share of the National Computational Infrastructure's peak facility$40,000

Funding body: University of Newcastle

Funding body University of Newcastle
Project Team Associate Professor Evatt Hawkes, Professor Marc Wilkins, Assoc. Prof Aibing Yu, Professor Michael Ferry, Dr Graham Ball, Professor Geraint Lewis, Professor Dietmar Muller, Professor Leo Radom, Professor Catherine Stampfl, Dr Jeffrey Reimers, Associate Professor Christopher Poulton, Associate Professor Michael Ford, Dr Adel Rahmani, Dr Matthew Arnold, Dr Kei-Wai Cheung, Professor Mark Johnson, Associate Professor Orsola De Marco, Conjoint Associate Professor Frans Henskens, Conjoint Professor Bogdan Dlugogorski, Conjoint Professor Peter Greer, Dr Haibo Yu, Professor Willy Susilo, Professor Abdulkadir Sajeev, Associate Professor Cedric Gondro, Associate Professor Chunhui Yang, Dr Ming Zhao, Professor Graham King, Professor Terry Bossomaier, Professor Arthur Georges
Scheme Equipment Grant
Role Investigator
Funding Start 2014
Funding Finish 2014
GNo G1300203
Type Of Funding Internal
Category INTE
UON Y

Rapid learning from datamining routine clinical datasets in radiotherapy$20,000

Funding body: Hunter Cancer Research Alliance

Funding body Hunter Cancer Research Alliance
Project Team

Lehmann J, Thwaites D, Ludbrook J, Dekker A, Holloway L, Greer PB, Vinod S

Scheme Pilot
Role Investigator
Funding Start 2014
Funding Finish 2016
GNo
Type Of Funding Other Public Sector - Local
Category 2OPL
UON N

20134 grants / $435,980

Safety and Quality: IMRT Treatment Delivery Accuracy$216,307

Funding body: ROI (Radiation Oncology Institute) USA

Funding body ROI (Radiation Oncology Institute) USA
Project Team Conjoint Professor Peter Greer, Dr Jarad Martin, Professor Paul Keall, Dr Michael Lovelock, Dr Yoshiya Yamada, Dr Boyd McCurdy, Dr James Butler, Dr Jeffrey Siebers, Associate Professor Elisabeth Weiss
Scheme Research Grant
Role Lead
Funding Start 2013
Funding Finish 2014
GNo G1300205
Type Of Funding International - Competitive
Category 3IFA
UON Y

The Australian MRI-Linac Program: Improving cancer treatment through real-time image guided adaptive radiotherapy$149,527

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team Professor Paul Keall, Professor Michael Barton, Professor Stuart Crozier, Conjoint Professor Peter Greer
Scheme Program Grant
Role Lead
Funding Start 2013
Funding Finish 2017
GNo G1200920
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON Y

Pre-treatment verification of VMAT and in-vivo verification of patient treatments$50,146

Funding body: Calvary Mater Newcastle

Funding body Calvary Mater Newcastle
Project Team Conjoint Professor Peter Greer, Dr Jarad Martin, Professor Paul Keall, Dr Michael Lovelock, Dr Yoshiya Yamada, Dr Boyd McCurdy, Dr James Butler, Dr Jeffrey Siebers, Associate Professor Elisabeth Weiss
Scheme Project Grant
Role Lead
Funding Start 2013
Funding Finish 2013
GNo G1300893
Type Of Funding Contract - Aust Non Government
Category 3AFC
UON Y

Real-time verification of dynamic radiotherapy$20,000

Funding body: Hunter Cancer Research Alliance

Funding body Hunter Cancer Research Alliance
Scheme Pilot
Role Lead
Funding Start 2013
Funding Finish 2016
GNo
Type Of Funding Other Public Sector - Local
Category 2OPL
UON N

20126 grants / $1,273,437

An adaptable and dedicated linear accelerator for medical radiation research$600,000

Funding body: ARC (Australian Research Council)

Funding body ARC (Australian Research Council)
Project Team

Paul Keall

Scheme Linkage Infrastructure Equipment & Facilities (LIEF)
Role Investigator
Funding Start 2012
Funding Finish 2013
GNo
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON N

Development of high precision MRI based prostate cancer radiation therapy$300,000

Funding body: Prostate Cancer Foundation of Australia

Funding body Prostate Cancer Foundation of Australia
Project Team

Jason Dowling

Scheme Young Investigator Award
Role Investigator
Funding Start 2012
Funding Finish 2013
GNo
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON N

Project EVA: an environmentally responsible facility for interdisciplinary supercomputing applications$263,000

Funding body: University of Newcastle

Funding body University of Newcastle
Project Team Professor Pablo Moscato, Laureate Professor Jon Borwein, Conjoint Professor Keith Jones, Conjoint Professor Chris Levi, Professor Mark Parsons, Professor Michael Ostwald, Professor Hugh Craig, Conjoint Professor Peter Greer, Associate Professor Stephan Chalup, Professor Regina Berretta
Scheme Equipment Grant
Role Investigator
Funding Start 2012
Funding Finish 2012
GNo G1100627
Type Of Funding Internal
Category INTE
UON Y

Optimising radiation therapy delivery for cancer patients using daily image guidance to maximize cure and reduce normal tissue side effects$67,877

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team Doctor Farshad Foroudi, Dr Thomas Eade, Professor Tomas Kron, Dr David Ball, Conjoint Professor Peter Greer
Scheme Project Grant
Role Lead
Funding Start 2012
Funding Finish 2014
GNo G1200358
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON Y

Implementation of EPID imaging infrastructure for research and development$27,560

Funding body: Calvary Mater Newcastle

Funding body Calvary Mater Newcastle
Project Team Conjoint Professor Peter Greer
Scheme Project Grant
Role Lead
Funding Start 2012
Funding Finish 2013
GNo G1201179
Type Of Funding Contract - Aust Non Government
Category 3AFC
UON Y

An adaptable and dedicated linear accelerator for medical radiation research$15,000

Funding body: University of Newcastle

Funding body University of Newcastle
Project Team Professor Paul Keall, Associate Professor Michael Jackson, Professor Anatoly Rozenfeld, Professor Michael Barton, Conjoint Professor Peter Greer, Dr Philip Vial, Professor Clive Baldock, Professor Peter Metcalfe, Professor David Thwaites, Dr Zdenka Kuncic, Dr Lois Holloway, Dr Stephen Bosi, Dr Enid Eslick, Mr Simon Downes
Scheme Equipment Grant
Role Lead
Funding Start 2012
Funding Finish 2012
GNo G1100816
Type Of Funding Internal
Category INTE
UON Y

20114 grants / $722,920

Does the initial treatment plan predict doses delivered to normal tissues during prostate radiation therapy$349,795

Funding body: Cancer Council NSW

Funding body Cancer Council NSW
Project Team Conjoint Professor Peter Greer, Dr Jason Dowling, Conjoint Professor Jim Denham, Dr Olivier Salvado
Scheme Research Program
Role Lead
Funding Start 2011
Funding Finish 2016
GNo G1000377
Type Of Funding Grant - Aust Non Government
Category 3AFG
UON Y

A next generation detector for radiotherapy treatment verification with dual capability for simultaneous imaging and dosimetry$336,125

Funding body: Cancer Council NSW

Funding body Cancer Council NSW
Project Team

Philip Vial

Scheme Project Grant
Role Investigator
Funding Start 2011
Funding Finish 2013
GNo
Type Of Funding Grant - Aust Non Government
Category 3AFG
UON N

The Pierre and Marie Curie GPU computing servers$27,000

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team Professor Pablo Moscato, Conjoint Professor Peter Greer, Professor Regina Berretta, Doctor Carlos Riveros
Scheme Equipment Grant
Role Investigator
Funding Start 2011
Funding Finish 2011
GNo G1100032
Type Of Funding Other Public Sector - Commonwealth
Category 2OPC
UON Y

PULSE Early Career Medical Researcher of the Year Award$10,000

Funding body: Hunter Medical Research Institute

Funding body Hunter Medical Research Institute
Project Team Conjoint Professor Peter Greer
Scheme PULSE Early Career Researcher of the Year Award
Role Lead
Funding Start 2011
Funding Finish 2011
GNo G1001047
Type Of Funding Grant - Aust Non Government
Category 3AFG
UON Y

20105 grants / $812,058

Real-time dose monitoring for patient safety in radiation therapy$360,000

Funding body: Cancer Council NSW

Funding body Cancer Council NSW
Project Team Conjoint Professor Peter Greer, Dr Boyd McCurdy, Dr Zdenka Kuncic, Professor Clive Baldock, Conjoint Professor Jim Denham
Scheme Research Grant
Role Lead
Funding Start 2010
Funding Finish 2012
GNo G0190320
Type Of Funding Grant - Aust Non Government
Category 3AFG
UON Y

Making radiotherapy safer and more accurate: Developing detector technology for the next generation in treatment verification systems$198,000

Funding body: Cancer Institute NSW

Funding body Cancer Institute NSW
Project Team

Philip Vial

Scheme Research Equipment Grant
Role Investigator
Funding Start 2010
Funding Finish 2010
GNo
Type Of Funding Other Public Sector - State
Category 2OPS
UON N

Adaptive Radiotherapy Incorporating Patient Dosimetry Feedback$120,000

Funding body: Cancer Care Manitoba

Funding body Cancer Care Manitoba
Project Team

Boyd McCurdy

Scheme Cancer Care Manitoba Research Grant
Role Investigator
Funding Start 2010
Funding Finish 2011
GNo
Type Of Funding International - Non Competitive
Category 3IFB
UON N

Equipment to assess the accuracy of image-guided and advanced technology used in radiotherapy clinical trials$94,058

Funding body: Cancer Institute NSW

Funding body Cancer Institute NSW
Project Team

Peter Greer

Scheme Research Equipment Grant
Role Lead
Funding Start 2010
Funding Finish 2010
GNo
Type Of Funding Other Public Sector - State
Category 2OPS
UON N

Investigation of Magnetic Resonance Imaging for Prostate Radiation Therapy Planing (PHD Top-up)$40,000

Funding body: Hunter Medical Research Institute

Funding body Hunter Medical Research Institute
Project Team Conjoint Professor Peter Greer, Professor Fred Menk
Scheme Research Higher Degree Support Grant
Role Lead
Funding Start 2010
Funding Finish 2011
GNo G0900135
Type Of Funding Contract - Aust Non Government
Category 3AFC
UON Y

20093 grants / $779,816

Investigation of a new electronic portal imaging device for radiation therapy dose delivery$393,441

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team Conjoint Professor Peter Greer, Professor Clive Baldock, Dr Zdenka Kuncic, Conjoint Professor Jim Denham
Scheme Project Grant
Role Lead
Funding Start 2009
Funding Finish 2011
GNo G0188893
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON Y

Improving patient outcomes of radiotherapy treatments$365,375

Funding body: NHMRC (National Health & Medical Research Council)

Funding body NHMRC (National Health & Medical Research Council)
Project Team

A Fielding

Scheme Project Grant
Role Investigator
Funding Start 2009
Funding Finish 2011
GNo
Type Of Funding Aust Competitive - Commonwealth
Category 1CS
UON N

An investigation of adaptive radiation therapy for improved prostate cancer treatment outcomes$21,000

Funding body: Calvary Mater Newcastle Hospital

Funding body Calvary Mater Newcastle Hospital
Project Team

Joan Hatton

Scheme Wig Week Research Grant
Role Investigator
Funding Start 2009
Funding Finish 2009
GNo
Type Of Funding Other Public Sector - Local
Category 2OPL
UON N

20082 grants / $91,531

An investigation of pre-treatment cone-beam CT and adaptive planning for improved prostate cancer radiotherapy$68,531

Funding body: Cancer Institute NSW

Funding body Cancer Institute NSW
Project Team

Joan Hatton

Scheme Career Development Fellowship
Role Investigator
Funding Start 2008
Funding Finish 2008
GNo
Type Of Funding Other Public Sector - State
Category 2OPS
UON N

Radiation therapy treatment planning research infrastructure$23,000

Funding body: Calvary Mater Newcastle Hospital

Funding body Calvary Mater Newcastle Hospital
Project Team

Peter Greer

Scheme Coalfields and Wig Week Grant
Role Lead
Funding Start 2008
Funding Finish 2008
GNo
Type Of Funding Other Public Sector - Local
Category 2OPL
UON N

20075 grants / $504,878

High precision MRI based prostate radiotherapy$301,750

Funding body: Cancer Council NSW

Funding body Cancer Council NSW
Project Team Conjoint Professor Peter Greer, Conjoint Professor Jim Denham, Dr Sebastien Ourselin, Dr Martin Ebert, Doctor Trish Ostwald, Dr Peter Lau
Scheme Research Grant
Role Lead
Funding Start 2007
Funding Finish 2009
GNo G0186637
Type Of Funding Donation - Aust Non Government
Category 3AFD
UON Y

Improving the Verification of Intensity Modulated Radiation Therapy Dose Delivery with Flat-Panel Imagers$139,500

Funding body: Cancer Council NSW

Funding body Cancer Council NSW
Project Team Conjoint Professor Peter Greer, Dr Martin Ebert, Mr Patrick Cadman, Professor Clive Baldock, Conjoint Professor Jim Denham
Scheme Research Grant
Role Lead
Funding Start 2007
Funding Finish 2008
GNo G0186639
Type Of Funding Donation - Aust Non Government
Category 3AFD
UON Y

On-line verification of patient dose delivery in radiotherapy$25,000

Funding body: Calvary Mater Newcastle Hospital

Funding body Calvary Mater Newcastle Hospital
Project Team

Peter Greer

Scheme Wig Week Research Grant
Role Lead
Funding Start 2007
Funding Finish 2007
GNo
Type Of Funding Other Public Sector - Local
Category 2OPL
UON N

Improving the verification of intensity modulated radiation therapy with flat panel imagers$23,196

Funding body: Calvary Mater Newcastle

Funding body Calvary Mater Newcastle
Project Team Conjoint Professor Peter Greer, Professor Clive Baldock, Conjoint Professor Jim Denham
Scheme Project Grant
Role Lead
Funding Start 2007
Funding Finish 2008
GNo G0188380
Type Of Funding Contract - Aust Non Government
Category 3AFC
UON Y

Medical modelling computing grid$15,432

Funding body: Calvary Mater Newcastle Hospital

Funding body Calvary Mater Newcastle Hospital
Project Team

Peter Greer

Scheme Coalfields Equipment
Role Lead
Funding Start 2007
Funding Finish 2007
GNo
Type Of Funding Other Public Sector - Local
Category 2OPL
UON N

20052 grants / $111,454

NSW centre for research into quality of radiation therapy delivery$102,454

Funding body: Cancer Institute NSW

Funding body Cancer Institute NSW
Project Team Dr Martin Ebert, Mrs Kristie Harrison, Associate Professor Helen Warren-Forward, Conjoint Professor Peter Greer
Scheme Research Infrastructure Grants
Role Investigator
Funding Start 2005
Funding Finish 2005
GNo G0185063
Type Of Funding Not Known
Category UNKN
UON Y

Real-time dosimetry for intensity-modulated radiotherapy$9,000

Funding body: Calvary Mater Newcastle Hospital

Funding body Calvary Mater Newcastle Hospital
Project Team

Peter Greer

Scheme Margaret Mitchell Research Grant
Role Lead
Funding Start 2005
Funding Finish 2005
GNo
Type Of Funding Other Public Sector - Local
Category 2OPL
UON N

20042 grants / $75,000

Image-based in vivo patient and organ localisation in external beam radiotherapy$58,000

Funding body: Cure Cancer Australia Foundation

Funding body Cure Cancer Australia Foundation
Project Team Conjoint Professor Peter Greer
Scheme Research Grant
Role Lead
Funding Start 2004
Funding Finish 2004
GNo G0183186
Type Of Funding Contract - Aust Non Government
Category 3AFC
UON Y

Production of diagnostic-quality X-rays from a megavoltage radiotherapy beam$17,000

Funding body: Hunter Medical Research Institute

Funding body Hunter Medical Research Institute
Project Team Dr Martin Ebert, Conjoint Professor Peter Greer
Scheme Research Grant
Role Investigator
Funding Start 2004
Funding Finish 2004
GNo G0183750
Type Of Funding Contract - Aust Non Government
Category 3AFC
UON Y
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Research Supervision

Number of supervisions

Completed10
Current7

Total current UON EFTSL

Masters0.35
PhD2.35

Current Supervision

Commenced Level of Study Research Title Program Supervisor Type
2017 Masters Development of an MRI Only Imaging Protocol for Radiation Therapy Treatment Planning for Patients With Complex Pelvic Cancers. M Philosophy (Med RadiationSc), Faculty of Health and Medicine, The University of Newcastle Principal Supervisor
2016 PhD Linear Accelerator Quality Assurance for Modern Radiotherapy Clinical Practice PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2015 PhD Investigations of EPID Based Dosimetry Methods for use in MRI-Linac Radiotherapy PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2015 PhD Improved Prostate Tumour Identification and Delineation Using Multiparametric Magnetic Resonance Imaging PhD (Magnet Resonance in Med), Faculty of Health and Medicine, The University of Newcastle Principal Supervisor
2014 PhD Remote EPID-Based Dosimetry for Credentialing Radiation Therapies PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2014 Masters The Use of 3D Ultrasound in the Radiation Therapy Simulation of Breast Cancer M Philosophy (Med RadiationSc), Faculty of Health and Medicine, The University of Newcastle Co-Supervisor
2013 PhD Investigations of EPID Based Dosimetry Methods for Use in MRI-Linac Radiotherapy PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor

Past Supervision

Year Level of Study Research Title Program Supervisor Type
2017 PhD Hypofractionated Prostate Treatments: Dose, Motion Monitoring and Credentialling PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2016 PhD Real-Time Radiotherapy Error Detection Using Transit Beam Image Processing PhD (Electrical Engineering), Faculty of Engineering and Built Environment, The University of Newcastle Co-Supervisor
2016 PhD Real-Time Radiotherapy Error Detection Using Transit Beam Image Processing PhD (Electrical Engineering), Faculty of Science, The University of Newcastle Co-Supervisor
2015 PhD Development of Magnetic Resonance Imaging Based Prostate Treatment Planning PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2013 PhD Investigation of Magnetic Resonance lmaging for Prostate Radiation Therapy Planning With Cone-Beam CT-Based Image Guided Radiation Therapy PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2013 Masters Development of Epid-Based Real-Time Dosimetry and Geometry in Radiation Therapy M Philosophy (Medical Physics), Faculty of Engineering and Built Environment, The University of Newcastle Principal Supervisor
2013 Masters Development of Epid-Based Real-Time Dosimetry and Geometry in Radiation Therapy M Philosophy (Medical Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2012 PhD Investigation of a Modified Electronic Portal Imaging Device for Improving Dosimetry in Radiotherapy PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2012 PhD Improvement of EPID-based Techniques for Dosimetry and Investigation of Linac Mechanical Performance in Advanced Radiotherapy PhD (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
2011 Masters Electronic Portal Imaging for Verification of Intensity Modulated Radiotherapy M Philosophy (Physics), Faculty of Science, The University of Newcastle Principal Supervisor
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Conjoint Professor Peter Greer

Position

Conjoint Professor
Medical Physics Group
School of Mathematical and Physical Sciences
Faculty of Science

Focus area

Physics

Contact Details

Email peter.greer@newcastle.edu.au
Phone (02) 4014 3689
Fax (02) 4014 3169

Office

Room 5.09 C, Radiation Oncology Department.
Building Mater Hospital
Location Mater

,
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