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Title: Leakage and scatter radiation from a double scattering based proton beamline

Abstract

Proton beams offer several advantages over conventional radiation techniques for treating cancer and other diseases. These advantages might be negated if the leakage and scatter radiation from the beamline and patient are too large. Although the leakage and scatter radiation for the double scattering proton beamlines at the Loma Linda University Proton Treatment Facility were measured during the acceptance testing that occurred in the early 1990s, recent discussions in the radiotherapy community have prompted a reinvestigation of this contribution to the dose equivalent a patient receives. The dose and dose equivalent delivered to a large phantom patient outside a primary proton field were determined using five methods: simulations using Monte Carlo calculations, measurements with silver halide film, measurements with ionization chambers, measurements with rem meters, and measurements with CR-39 plastic nuclear track detectors. The Monte Carlo dose distribution was calculated in a coronal plane through the simulated patient that coincided with the central axis of the beam. Measurements with the ionization chambers, rem meters, and plastic nuclear track detectors were made at multiple locations within the same coronal plane. Measurements with the film were done in a plane perpendicular to the central axis of the beam and coincident with themore » surface of the phantom patient. In general, agreement between the five methods was good, but there were some differences. Measurements and simulations also tended to be in agreement with the original acceptance testing measurements and results from similar facilities published in the literature. Simulations illustrated that most of the neutrons entering the patient are produced in the final patient-specific aperture and precollimator just upstream of the aperture, not in the scattering system. These new results confirm that the dose equivalents received by patients outside the primary proton field from primary particles that leak through the nozzle are below the accepted standards for x-ray and electron beams. The total dose equivalent outside of the field is similar to that received by patients undergoing treatments with intensity modulated x-ray therapy. At the center of a patient for a whole course of treatment, the dose equivalent is comparable to that delivered by a single whole-body XCT scan.« less

Authors:
; ; ;  [1]
  1. Proton Therapy, Inc., Colton, California 92324 (United States)
Publication Date:
OSTI Identifier:
21036121
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 35; Journal Issue: 1; Other Information: DOI: 10.1118/1.2805086; (c) 2008 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; COMPUTERIZED TOMOGRAPHY; DOSE EQUIVALENTS; DOSIMETRY; ELECTRON BEAMS; IONIZATION CHAMBERS; MONTE CARLO METHOD; NEOPLASMS; NEUTRONS; PATIENTS; PHANTOMS; PROTON BEAMS; RADIATION DOSES; RADIOTHERAPY; X RADIATION

Citation Formats

Moyers, M F, Benton, E R, Ghebremedhin, A, Coutrakon, G, Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078, and Loma Linda University Medical Center, Department of Radiation Medicine, Loma Linda, California 92354. Leakage and scatter radiation from a double scattering based proton beamline. United States: N. p., 2008. Web. doi:10.1118/1.2805086.
Moyers, M F, Benton, E R, Ghebremedhin, A, Coutrakon, G, Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078, & Loma Linda University Medical Center, Department of Radiation Medicine, Loma Linda, California 92354. Leakage and scatter radiation from a double scattering based proton beamline. United States. https://doi.org/10.1118/1.2805086
Moyers, M F, Benton, E R, Ghebremedhin, A, Coutrakon, G, Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078, and Loma Linda University Medical Center, Department of Radiation Medicine, Loma Linda, California 92354. 2008. "Leakage and scatter radiation from a double scattering based proton beamline". United States. https://doi.org/10.1118/1.2805086.
@article{osti_21036121,
title = {Leakage and scatter radiation from a double scattering based proton beamline},
author = {Moyers, M F and Benton, E R and Ghebremedhin, A and Coutrakon, G and Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078 and Loma Linda University Medical Center, Department of Radiation Medicine, Loma Linda, California 92354},
abstractNote = {Proton beams offer several advantages over conventional radiation techniques for treating cancer and other diseases. These advantages might be negated if the leakage and scatter radiation from the beamline and patient are too large. Although the leakage and scatter radiation for the double scattering proton beamlines at the Loma Linda University Proton Treatment Facility were measured during the acceptance testing that occurred in the early 1990s, recent discussions in the radiotherapy community have prompted a reinvestigation of this contribution to the dose equivalent a patient receives. The dose and dose equivalent delivered to a large phantom patient outside a primary proton field were determined using five methods: simulations using Monte Carlo calculations, measurements with silver halide film, measurements with ionization chambers, measurements with rem meters, and measurements with CR-39 plastic nuclear track detectors. The Monte Carlo dose distribution was calculated in a coronal plane through the simulated patient that coincided with the central axis of the beam. Measurements with the ionization chambers, rem meters, and plastic nuclear track detectors were made at multiple locations within the same coronal plane. Measurements with the film were done in a plane perpendicular to the central axis of the beam and coincident with the surface of the phantom patient. In general, agreement between the five methods was good, but there were some differences. Measurements and simulations also tended to be in agreement with the original acceptance testing measurements and results from similar facilities published in the literature. Simulations illustrated that most of the neutrons entering the patient are produced in the final patient-specific aperture and precollimator just upstream of the aperture, not in the scattering system. These new results confirm that the dose equivalents received by patients outside the primary proton field from primary particles that leak through the nozzle are below the accepted standards for x-ray and electron beams. The total dose equivalent outside of the field is similar to that received by patients undergoing treatments with intensity modulated x-ray therapy. At the center of a patient for a whole course of treatment, the dose equivalent is comparable to that delivered by a single whole-body XCT scan.},
doi = {10.1118/1.2805086},
url = {https://www.osti.gov/biblio/21036121}, journal = {Medical Physics},
issn = {0094-2405},
number = 1,
volume = 35,
place = {United States},
year = {Tue Jan 15 00:00:00 EST 2008},
month = {Tue Jan 15 00:00:00 EST 2008}
}