Zhu Libing, Du Yi, Peng Yahui, Xiang Xincheng, Wang Xiangang
Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China.
Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Gels. 2023 Mar 10;9(3):212. doi: 10.3390/gels9030212.
With the complexity and high demands on quality assurance (QA) of photon beam radiation therapy, end-to-end (E2E) QA is necessary to validate the entire treatment workflow from pre-treatment imaging to beam delivery. A polymer gel dosimeter is a promising tool for three-dimensional (3D) dose distribution measurement. The purpose of this study is to design a fast "one delivery" polymethyl methacrylate (PMMA) phantom with a polymer gel dosimeter for the E2E QA test of the photon beam. The one delivery phantom is composed of ten calibration cuvettes for the calibration curve measurement, two 10 cm gel dosimeter inserts for the dose distribution measurement, and three 5.5 cm gel dosimeters for the square field measurement. The one delivery phantom holder is comparable in size and shape to that of a human thorax and abdomen. In addition, an anthropomorphic head phantom was employed to measure the patient-specific dose distribution of a VMAT plan. The E2E dosimetry was verified by undertaking the whole RT procedure (immobilization, CT simulation, treatment planning, phantom set-up, imaged-guided registration, and beam delivery). The calibration curve, field size, and patient-specific dose were measured with a polymer gel dosimeter. The positioning error can be mitigated with the one-delivery PMMA phantom holder. The delivered dose measured with a polymer gel dosimeter was compared with the planned dose. The gamma passing rate is 86.64% with the MAGAT-f gel dosimeter. The results ascertain the feasibility of the one delivery phantom with a polymer gel dosimeter for a photon beam in E2E QA. The QA time can be reduced with the designed one delivery phantom.
由于光子束放射治疗的复杂性和对质量保证（QA）的高要求，端到端（E2E）QA对于验证从治疗前成像到束流输送的整个治疗工作流程是必要的。聚合物凝胶剂量计是一种用于三维（3D）剂量分布测量的有前途的工具。本研究的目的是设计一种带有聚合物凝胶剂量计的快速“单次输送”聚甲基丙烯酸甲酯（PMMA）模体，用于光子束的E2E QA测试。单次输送模体由十个用于校准曲线测量的校准比色皿、两个用于剂量分布测量的10 cm凝胶剂量计插入件和三个用于方形野测量的5.5 cm凝胶剂量计组成。单次输送模体支架在尺寸和形状上与人体胸部和腹部相当。此外，还采用了一个仿真人头模体来测量容积调强弧形治疗（VMAT）计划的患者特定剂量分布。通过进行整个放疗程序（固定、CT模拟、治疗计划、模体设置、影像引导配准和束流输送）来验证E2E剂量测定。用聚合物凝胶剂量计测量校准曲线、射野尺寸和患者特定剂量。使用单次输送的PMMA模体支架可以减轻定位误差。将用聚合物凝胶剂量计测量的输送剂量与计划剂量进行比较。使用MAGAT-f凝胶剂量计的γ通过率为86.64%。结果确定了带有聚合物凝胶剂量计的单次输送模体用于光子束E2E QA的可行性。使用所设计的单次输送模体可以减少QA时间。
