TY - JOUR

T1 - Evaluation of radiophotoluminescent glass dosimeter response for therapeutic spot scanning proton beam

T2 - suggestion of linear energy transfer-based correction

AU - Nagata, Junya

AU - Yasui, Keisuke

AU - Omachi, Chihiro

AU - Toshiyuki, Toshito

AU - Shimizu, Hidetoshi

AU - Aoyama, Takahiro

AU - Hayashi, Naoki

N1 - Funding Information:
We appreciate the cooperation of Fujita Health University, Nagoya Proton Therapy Center, and Aichi Cancer Center Hospital for their support of this study.
Publisher Copyright:
© 2021 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine

PY - 2021/8

Y1 - 2021/8

N2 - A radiophotoluminescent glass dosimeter (RGD) is used for a postal audit of a photon beam because of its various excellent characteristics. However, it has not been used for scanning proton beams because its response characteristics have not been verified. In this study, the response of RGD to scanning protons was investigated to develop a dosimetry protocol using the linear energy transfer (LET)-based correction factor. The responses of RGD to four maximum-range-energy-pattern proton beams were verified by comparing it with ionization chamber (IC) dosimetry. The LET at each measurement depth was calculated via Monte Carlo (MC) simulation. The LET correction factor ((Formula presented.)) was the ratio between the uncorrected RGD dose ((Formula presented.)) and the IC dose at each measurement depth. (Formula presented.) can be represented as a function of LET using the following equation: (Formula presented.). (Formula presented.) showed a linear under-response with increasing LET, and the maximum dose difference between the IC dose and (Formula presented.) was 15.2% at an LET of 6.07 keV/μm. The LET-based correction dose ((Formula presented.)) conformed within 3.6% of the IC dose. The mean dose difference (±SD) of (Formula presented.) and (Formula presented.) was –2.5 ± 6.9% and 0.0 ± 1.6%, respectively. To achieve accurate dose verification for scanning proton beams using RGD, we derived a linear regression equation based on LET. The results show that with appropriate LET correction, RGD can be used for dose verification of scanning proton beams.

AB - A radiophotoluminescent glass dosimeter (RGD) is used for a postal audit of a photon beam because of its various excellent characteristics. However, it has not been used for scanning proton beams because its response characteristics have not been verified. In this study, the response of RGD to scanning protons was investigated to develop a dosimetry protocol using the linear energy transfer (LET)-based correction factor. The responses of RGD to four maximum-range-energy-pattern proton beams were verified by comparing it with ionization chamber (IC) dosimetry. The LET at each measurement depth was calculated via Monte Carlo (MC) simulation. The LET correction factor ((Formula presented.)) was the ratio between the uncorrected RGD dose ((Formula presented.)) and the IC dose at each measurement depth. (Formula presented.) can be represented as a function of LET using the following equation: (Formula presented.). (Formula presented.) showed a linear under-response with increasing LET, and the maximum dose difference between the IC dose and (Formula presented.) was 15.2% at an LET of 6.07 keV/μm. The LET-based correction dose ((Formula presented.)) conformed within 3.6% of the IC dose. The mean dose difference (±SD) of (Formula presented.) and (Formula presented.) was –2.5 ± 6.9% and 0.0 ± 1.6%, respectively. To achieve accurate dose verification for scanning proton beams using RGD, we derived a linear regression equation based on LET. The results show that with appropriate LET correction, RGD can be used for dose verification of scanning proton beams.

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U2 - 10.1002/acm2.13378

DO - 10.1002/acm2.13378

M3 - Article

C2 - 34339583

AN - SCOPUS:85111926898

VL - 22

SP - 265

EP - 272

JO - Journal of Applied Clinical Medical Physics

JF - Journal of Applied Clinical Medical Physics

SN - 1526-9914

IS - 8

ER -