Study on the Performance of Two-Dimensional Semiconductor Matrix and Its Application in Dose Verification of Multi-Target Radiotherapy Plan
LI Xiaohong1, MEI Jie2, LONG Hao3, YANG Jing2
1. Department of Oncology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan Hubei 430077, China; 2. Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan Hubei 430022, China; 3. College of Electronic and Information Engineering, South-Central Minzu University,
Wuhan Hubei 430074, China
Abstract：Objective To test the performance of MapCHECK2 (two-dimensional semiconductor matrix detector) and verify its effect on intensity modulated radiation therapy (IMRT), especially the dose verification of multi-target radiotherapy plans. Methods Used the 6 MV photon beam of Precise accelerator under specific irradiation conditions, took the measured average value of five detectors within 5 mm of the central axes of matrix as the point dose value, and analyzed the dose repeatability, dose linearity and dose rate response. The symmetry and angular response were studied by gamma indices analysis comparing the dose distributions calculated by matrix measurement and the planning system. Forty cases of IMRT plans for tumors in different parts were selected, and a matrix-based QA angle plan was developed and dose validation was performed. Results The maximum deviation of matrix repeatability was not exceed 0.18%, the dose linear determination coefficient R2=1, and the dose-rate deviation was not greater than 1.6%. The deviation of gamma passing rate was not more than 0.21% for the symmetry of 0°and 180°. The γ
(3%/2 mm) passing rate was greater than 96.4% in the range of 80° deflection with vertical incidence (gantry 0°~80° and 280°~0°), the γ (2%/2 mm) passing rate was greater than 92.4% in the range of 60° deflection with vertical incidence ( gantry 0°~60° and 300°~0°). The average γ (3%/2 mm) and γ (2%/2 mm) passing rate of 40 IMRT plans were 98.3%±0.3%/98.5%±0.4% and 96.5%±0.6%/96.7%±0.8% respectively. Conclusion The performance of the MapCHECK2 semiconductor matrix detector meets the dose verification work under the vertical single beam sequential irradiation method in the clinical IMRT plans of tumors at various parts based on 6 MV uniform photon beam. The dose verification under the real composite method requires the equipment to be equipped with specially designed phantom.
李小红1，梅杰2，龙浩3，杨晶2. 二维半导体矩阵的性能及在多靶点放疗计划剂量验证中的应用研究[J]. 中国医疗设备, 2022, 37(4): 23-26.
LI Xiaohong1, MEI Jie2, LONG Hao3, YANG Jing2. Study on the Performance of Two-Dimensional Semiconductor Matrix and Its Application in Dose Verification of Multi-Target Radiotherapy Plan. China Medical Devices, 2022, 37(4): 23-26.
