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Session Information

2009 Annual Meeting

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Emerging Themes in Proton Radiation Therapy

Track : Panel

Program Code: PAN10

Date: Monday, November 2, 2009

Time: 3:45 PM to 5:15 PM EST

Duration: 90 Minutes

Location: W184

SPEAKER(S):

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James Metz, Radiation Oncologist, University of Pennsylvania

Ajay Kapur, Physicist

WORK EXPERIENCE Current: Director of Medical Physics and Dosimetry, ProCure Proton Therapy Center, Oklahoma City, OK 2005-2009: Assistant Professor of Radiation Oncology, Columbia University, New York, NY 1999-2005: Senior Systems Engineer, General Electric Global Research, Schenectady, NY RESEARCH / CLINICAL INTERESTS: Monte Carlo Dose Calculations in Radiation Therapy Image Guided Radiation Therapy TEACHING: 2005-2009: Faculty Council of Columbia University Medical Center, NY 2005-2009: Taught a 3 credit course "Diagnostic Radiological Physics" to graduate students of Medical Physics CLINICAL MEDICAL PHYSICS EXPERIENCE Commissioning of Linear Accelerators, Brachytherapy Systems, Proton Therapy Systems, Treatment Planning, Dosimetry, QA Radiation Safet,y. SELECT PUBLICATIONS AND PATENTS: Abdalrahman A Al-Khalidy, Kapur A., Eberhard J., Souchay H., Shoemaker P., 2008, United States Patent 7349521 Compression paddle for mammography systems Rebecca C. Booi, Jochen F. Krcker, Mitchell M. Goodsitt, MatthewODonnell, Ajay Kapur, Gerald L. LeCarpentier, Marilyn A. Roubidoux, J. Brian Fowlkes and Paul L. Carson, Evaluating Thin Compression Paddles for Mammographically CompatibleUltrasound, Ultrasound in Medicine & Biology, 2007, Vol. 33, no. 3, Page 472-482. Alyassin A., Kapur A., 2007, United States Patent 7313259, Method, system and computer program product for multi-modality registration using virtual cursors Eberhard J., Alyassin A., Kapur A., 2007, United States Patent 7218766 Computer aided detection (CAD) for 3D digital mammography Lokhandwalla M., Kapur A., 2007, United States Patent 7299806 Compliant probe interface assembly Claus B. Kapur A., Eberhard J, 2005, United States Patent 6940943 Continuous scan tomosynthesis system and method Kapur A., Thomenius K, 2005, United States Patent Publication 20050288581 Acoustic coupling gel for combined mammography and ultrasound image acquisition and methods thereof Kapur A.,Carson P, Eberhard JW, Goodsitt M, et al, Combinationof digital mammography and 3D semi-automated breast ultrasound, Technologies in Cancer Research and Treatment, 2004, Vol. 3, no. 4, Page 309-410 Kapur A et al, 2003, United States Patent Publication 20030149364, Methods, system and apparatus for digital imaging Miften M., Wiesmeyer M., Kapur A., and Ma C.-M., Comparison of RTP dose distributions in heterogeneous phantoms with the BEAMMonte Carlo simulation system Journal of Applied Clinical Medical Physics, Vol. 2, Issue 1, Page 21-31. Ma C.-M, Pawlicki T., Jiang S.B., Li, J.S., Deng, J., Mok E.C.,Kapur A.,Xing, L., Ma, L. and Boyer, A.L., Monte Carlo verificationof IMRT dose distributions from a commercial treatment planning optimization system, Physics in Medicine and Biology, 2000, vol.45, no.9 , Page: 2483-95. Deng J., Jiang, S.B., Kapur, A., Li J, Pawlicki, T. and Ma, C.-M., Photon beam characterization and modeling for Monte Carlotreatment planning, Physics in Medicine and Biology , vol.45, no.2 , Page: 411-27. Jiang S.B., Kapur A. and Ma C.-M, Electron beam modeling and commissioning for Monte Carlo treatment planning, Medical Physics, vol.27, no.1, Page: 180-91. Ma C. M, Mok E.C., Kapur A., Findley D., Brain S. and Boyer A.L., Clinical implementation of a Monte Carlo treatment planning system,Medical Physics, vol.26, no.10, Page: 2133-43. Kapur A., Ma C.-M, Stopping power ratios for clinical electron beams from a scatter-foil linear accelerator, Physics in Medicine and Biology, 1999, vol.44, no.9, Page: 2321-41. Kapur A., Ma C.-M, Mok E.C., Findley D and Boyer A.L., Monte Carlo calculations of electron beam output factors for a medical linear accelerator, Physics in Medicine and Biology, 1998 vol.43, no.12,Page:3479-94.

Sameer Keole, Radiation Oncologist, University of Florida Proton Therapy Institute

Wen Hsi, Assistant Professor, University of Florida Proton Therapy Institute

The mansucript with a title of 'In-vivo verification of proton beam path by using post-treatment PET/CT imaging' will be published in Medical Physics. The purpose of this study is to establish the in vivo verification of proton beam path by using proton-activated positron emission distributions. A total of 50 PET/CT imaging studies were performed on ten prostate cancer patients immediately after daily proton therapy treatment through a single lateral portal. The PET/CT and planning CT were registered by matching the pelvic bones, and the beam path of delivered protons was defined in vivo by the positron emission distribution seen only within the pelvic bones, referred to as the PET-defined beam path. Because of the patient position correction at each fraction, the marker-defined beam path, determined by the centroid of implanted markers seen in the posttreatment post-Tx CT, is used for the planned beam path. The angular variation and discordance between the PET- and marker-defined paths were derived to investigate the intrafraction prostate motion. For studies with large discordance, the relative location between the centroid and pelvic bones seen in the post-Tx CT was examined. The PET/CT studies are categorized for distinguishing the prostate motion that occurred before or after beam delivery. The post-PET CT was acquired after PET imaging to investigate prostate motion due to physiological changes during the extended PET acquisition.The less than 2 of angular variation indicates that the patient roll was minimal within the immobilization device. Thirty of the 50 studies with small discordance, referred as good cases, show a consistent alignment between the field edges and the positron emission distributions from the entrance to the distal edge. For those good cases, average displacements are 0.6 and 1.3 mm along the anterior-posterior DAP and superior-inferior DSI directions, respectively, with 1.6 mm standard deviations in both directions. For the remaining 20 studies demonstrating a large discordance more than 6 mm in either DAP or DSI, 13 studies, referred as motion-after-Tx cases, also show large misalignment between the field edge and the positron emission distribution in lipomatous tissues around the prostate. These motion-after-Tx cases correspond to patients with large changes in volume of rectal gas between the post-Tx and the post-PET CTs. The standard deviations for DAP and DSI are 5.0 and 3.0 mm, respectively, for these motion-after-Tx cases. The final seven studies, referred to as position-error cases, which had a large discordance but no misalignment, were found to have deviations of 4.6 and 3.6 mm in DAP and DSI, respectively. The positionerror cases correspond to a large discrepancy on the relative location between the centroid and pelvic bones seen in post-Tx CT and recorded x-ray radiographs.Systematic analyses of proton-activated positron emission distributions provide patient-specific information on prostate motion M and patient position variability p during daily proton beam delivery. The less than 2 mm of displacement variations in the good cases indicates that population-based values of p and M used in margin algorithms for treatment planning at the authors institution are valid for the majority of cases. However, a small fraction of PET/CT studies approximately 14% with 4 mm displacement variations may require different margins. Such data are useful in establishing patient-specific planning target volume margins.

Hanne Kooy, Professor, Massachusetts General Hospital, Northeast Proton Therapy Center

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