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Title: Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams

Abstract

Purpose: Neutron exposure is of concern in proton therapy, and varies with beam delivery technique, nozzle design, and treatment conditions. Uniform scanning is an emerging treatment technique in proton therapy, but neutron exposure for this technique has not been fully studied. The purpose of this study is to investigate the neutron dose equivalent per therapeutic dose, H/D, under various treatment conditions for uniform scanning beams employed at our proton therapy center. Methods: Using a wide energy neutron dose equivalent detector (SWENDI-II, ThermoScientific, MA), the authors measured H/D at 50 cm lateral to the isocenter as a function of proton range, modulation width, beam scanning area, collimated field size, and snout position. They also studied the influence of other factors on neutron dose equivalent, such as aperture material, the presence of a compensator, and measurement locations. They measured H/D for various treatment sites using patient-specific treatment parameters. Finally, they compared H/D values for various beam delivery techniques at various facilities under similar conditions. Results: H/D increased rapidly with proton range and modulation width, varying from about 0.2 mSv/Gy for a 5 cm range and 2 cm modulation width beam to 2.7 mSv/Gy for a 30 cm range and 30 cm modulationmore » width beam when 18 Multiplication-Sign 18 cm{sup 2} uniform scanning beams were used. H/D increased linearly with the beam scanning area, and decreased slowly with aperture size and snout retraction. The presence of a compensator reduced the H/D slightly compared with that without a compensator present. Aperture material and compensator material also have an influence on neutron dose equivalent, but the influence is relatively small. H/D varied from about 0.5 mSv/Gy for a brain tumor treatment to about 3.5 mSv/Gy for a pelvic case. Conclusions: This study presents H/D as a function of various treatment parameters for uniform scanning proton beams. For similar treatment conditions, the H/D value per uncollimated beam size for uniform scanning beams was slightly lower than that from a passive scattering beam and higher than that from a pencil beam scanning beam, within a factor of 2. Minimizing beam scanning area could effectively reduce neutron dose equivalent for uniform scanning beams, down to the level close to pencil beam scanning.« less

Authors:
; ; ; ;  [1];  [2];  [2];  [2];  [2]
  1. ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22098881
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 39; Journal Issue: 6; Other Information: (c) 2012 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; 62 RADIOLOGY AND NUCLEAR MEDICINE; BRAIN; DOSE EQUIVALENTS; MODULATION; NEOPLASMS; NEUTRON DETECTION; NEUTRONS; PATIENTS; PROTON BEAMS; PROTONS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Zheng Yuanshui, Liu Yaxi, Zeidan, Omar, Schreuder, Andries Niek, Keole, Sameer, INTEGRIS Cancer Insititute, 5911 West Memorial Road, Oklahoma City, Oklahoma 73142, ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142, ProCure Treatment Centers, 420 North Walnut Street, Bloomington, Indiana 47404, and ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142. Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams. United States: N. p., 2012. Web. doi:10.1118/1.4718685.
Zheng Yuanshui, Liu Yaxi, Zeidan, Omar, Schreuder, Andries Niek, Keole, Sameer, INTEGRIS Cancer Insititute, 5911 West Memorial Road, Oklahoma City, Oklahoma 73142, ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142, ProCure Treatment Centers, 420 North Walnut Street, Bloomington, Indiana 47404, & ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142. Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams. United States. doi:10.1118/1.4718685.
Zheng Yuanshui, Liu Yaxi, Zeidan, Omar, Schreuder, Andries Niek, Keole, Sameer, INTEGRIS Cancer Insititute, 5911 West Memorial Road, Oklahoma City, Oklahoma 73142, ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142, ProCure Treatment Centers, 420 North Walnut Street, Bloomington, Indiana 47404, and ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142. Fri . "Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams". United States. doi:10.1118/1.4718685.
@article{osti_22098881,
title = {Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams},
author = {Zheng Yuanshui and Liu Yaxi and Zeidan, Omar and Schreuder, Andries Niek and Keole, Sameer and INTEGRIS Cancer Insititute, 5911 West Memorial Road, Oklahoma City, Oklahoma 73142 and ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142 and ProCure Treatment Centers, 420 North Walnut Street, Bloomington, Indiana 47404 and ProCure Proton Therapy Center, 5901 West Memorial Road, Oklahoma City, Oklahoma 73142},
abstractNote = {Purpose: Neutron exposure is of concern in proton therapy, and varies with beam delivery technique, nozzle design, and treatment conditions. Uniform scanning is an emerging treatment technique in proton therapy, but neutron exposure for this technique has not been fully studied. The purpose of this study is to investigate the neutron dose equivalent per therapeutic dose, H/D, under various treatment conditions for uniform scanning beams employed at our proton therapy center. Methods: Using a wide energy neutron dose equivalent detector (SWENDI-II, ThermoScientific, MA), the authors measured H/D at 50 cm lateral to the isocenter as a function of proton range, modulation width, beam scanning area, collimated field size, and snout position. They also studied the influence of other factors on neutron dose equivalent, such as aperture material, the presence of a compensator, and measurement locations. They measured H/D for various treatment sites using patient-specific treatment parameters. Finally, they compared H/D values for various beam delivery techniques at various facilities under similar conditions. Results: H/D increased rapidly with proton range and modulation width, varying from about 0.2 mSv/Gy for a 5 cm range and 2 cm modulation width beam to 2.7 mSv/Gy for a 30 cm range and 30 cm modulation width beam when 18 Multiplication-Sign 18 cm{sup 2} uniform scanning beams were used. H/D increased linearly with the beam scanning area, and decreased slowly with aperture size and snout retraction. The presence of a compensator reduced the H/D slightly compared with that without a compensator present. Aperture material and compensator material also have an influence on neutron dose equivalent, but the influence is relatively small. H/D varied from about 0.5 mSv/Gy for a brain tumor treatment to about 3.5 mSv/Gy for a pelvic case. Conclusions: This study presents H/D as a function of various treatment parameters for uniform scanning proton beams. For similar treatment conditions, the H/D value per uncollimated beam size for uniform scanning beams was slightly lower than that from a passive scattering beam and higher than that from a pencil beam scanning beam, within a factor of 2. Minimizing beam scanning area could effectively reduce neutron dose equivalent for uniform scanning beams, down to the level close to pencil beam scanning.},
doi = {10.1118/1.4718685},
journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 39,
place = {United States},
year = {2012},
month = {6}
}