Angular dependence study on two-dimensional ionization chamber matrix detector in IMRT fields
10.3760/cma.j.cn121382-20200206-00408
- VernacularTitle:基于调强放疗射野下的二维电离室矩阵探测器的方向性响应研究
- Author:
Lifang LI
1
;
Hezheng ZHAI
;
Yongzhi WANG
;
Xin MING
;
Baolin HAN
Author Information
1. 天津市宝坻区人民医院放疗科，天津医科大学宝坻临床学院放疗科 301800
- From:
International Journal of Biomedical Engineering
2020;43(4):297-303
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To study the dose response of two-dimensional ionization chamber matrix detectors under IMRT fields irradiation at different gantry angles and different directions.Methods:After the dose calibration of the medical accelerator and the two-dimensional ionization chamber matrix detector respectively, the solid water phantom was used to cover the upper part of the two-dimensional ionization chamber matrix detector. Adjusting the thickness of the solid water, the effective distances between the effective measuring center of the two-dimensional ionization chamber matrix detector and the incident point of the central axis of the radiation on the surface of the phantom was always controlled at 5 cm. Four locations with 0、45、90 and 135 degrees of the long axis of the treatment bed were selected, and each location was irradiated by IMRT fields at different frame angle of 60°, 45°, 30°, 15°, 0°, -15°, -30°, -45° and -60°, respectively.Results:The dose deviation of the medical accelerator was less than 0.18% in the range of different rack angles. The directional response deviation of the two-dimensional ionization chamber matrix detector was less than 0.63%, and the measurement deviation of each probe of the two-dimensional ionization chamber matrix detector to its center probe was less than 0.50%.Conclusions:The two-dimensional ionization chamber matrix detector has good directional response and it is a useful tool for developing intensity-modulated radiotherapy technology. The method proposed in this study can provide a basic basis for the relevant medical accelerator metrology departments to formulate corresponding quality control test specifications.
