用于质子扩展布拉格峰束的 MOSFET 剂量测量。
MOSFET dose measurements for proton SOBP beam.
机构信息
Medical Physics Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Guishan Dist., Taoyuan City 333, Taiwan; Particle Physics and Beam Delivery Core Laboratory, Institute for Radiological Research, Chang Gung University/Chang Gung Memorial Hospital, Guishan, Taoyuan 333, Taiwan.
Department of Medical Imaging and Radiological Sciences, Chang Gung University, Guishan Dist., Taoyuan City 333, Taiwan.
出版信息
Phys Med. 2021 Jan;81:185-190. doi: 10.1016/j.ejmp.2020.12.007. Epub 2021 Jan 16.
PURPOSE
The aim of this work was to develop a computational scheme for the correction of the LET dependence on the MOSFET response in water phantom dose measurements for a spread-out Bragg peak (SOBP) proton beam.
METHODS
The LET dependence of MOSFET was attributed to the stopping power ratio of SiO to HO and to the fractional hole yield in the SiO layer. Using literature values for the stopping powers of the continuous slowing down approximation and measured fractional hole yields vs. electric field and LET, formulas were derived for the computation of a dose-weighted correction factor of a SOBP beam.
RESULTS
Dose-weighted correction factors were computed for a clinical 190-MeV proton SOBP beam in a high-density polyethylene phantom. By applying correction factors to the SOBP beam, which consisted of weighted monoenergetic Bragg peaks, the MOSFET outputs were predicted and agreed well with the measured MOSFET responses.
CONCLUSION
By applying LET dependent correction factors to MOSFET data, quality assurance of dose verification based on MOSFET measurements becomes possible for proton therapy.
目的
本工作旨在为扩展布拉格峰（SOBP）质子束水模剂量测量中 MOSFET 响应的 LET 依赖性开发一种计算方案。
方法
MOSFET 的 LET 依赖性归因于 SiO 与 HO 的阻止本领比以及 SiO 层中的空穴产额分数。利用连续慢化近似的阻止本领的文献值以及测量的空穴产额与电场和 LET 的关系，推导出了用于计算 SOBP 束剂量加权校正因子的公式。
结果
在高密度聚乙烯水模中计算了临床 190MeV 质子 SOBP 束的剂量加权校正因子。通过将由加权单能布拉格峰组成的 SOBP 束的校正因子应用于 MOSFET 数据，预测了 MOSFET 的输出并与实测的 MOSFET 响应吻合良好。
结论
通过将 LET 相关的校正因子应用于 MOSFET 数据，基于 MOSFET 测量的质子治疗剂量验证的质量保证成为可能。
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