Measurement performance of Gafchromic film dosimeter
10.3969/j.issn.1005-202X.2024.05.003
- VernacularTitle:自显影胶片剂量测量系统的测量性能
- Author:
Hui ZHANG
1
;
Hui ZHANG
;
Pingquan WANG
;
Junkai YANG
;
Fan LI
;
Ya'nan ZHANG
Author Information
1. 中国计量科学研究院,北京 100029
- Keywords:
Gafchromic film;
blackening time;
dosimetry range;
dosimetry resolution;
dose response non-uniformity
- From:
Chinese Journal of Medical Physics
2024;41(5):541-547
- CountryChina
- Language:Chinese
-
Abstract:
Objective To determine the applicable conditions and the film reading time of Gafchromic EBT3 film dosimeter through the research and test of the measurement performance such as blackening time,dosimetry range,dosimetry resolution and dose response non-uniformity.Methods Three Gafchromic films were exposure to different doses,and the optical densities were read at different moments after irradiation for analyzing and confirming the effects of blackening time on dose measurement and different doses on blackening time.The absorbed dose-optical density curve was used to determine Gafchromic film dosimetry range.The Gafchromic film dosimetry resolution was obtained by calculating the average optical densities of two groups with a dose difference of 0.01 Gy.The dose response non-uniformity of Gafchromic film was evaluated by irradiating the whole film and the cutting film.Results Relative to the optical density at the termination moment of irradiation,the optical density changes at 4 h were 1.69%(2 Gy),2.53%(4 Gy)and 2.13%(8 Gy);the changes at 24 h were 2.91%(2 Gy),3.31%(4 Gy)and 3.20%(8 Gy);and the changes at 48 h were 2.91%(2 Gy),3.31%(4 Gy)and 3.96%(8 Gy).The optical density given by Gafchromic film dosimeter within 0.1 to 10.0 Gy had a linear relationship with the absorbed dose,while the optical density of Gafchromic film dosimeter within 10.0 to 30.0 Gy had a nonlinear relationship with the absorbed dose,but there was still a one-to-one correspondence.The difference of the average optical densities of two groups was 0.004 when the inter-group dose difference was 0.01 Gy.The non-uniformity was 2.2%for the whole film and 2.8%for the cutting film.Conclusion Gafchromic EBT3 film reading time can be set at 24 h after irradiation,and the dose is independent of blackening time.Gafchromic film dosimeter can be used for point dosimetry and dose distribution measurement within 0.1 to 10.0 Gy,and point dosimetry within 10.0 to 30.0 Gy.The dosimetry resolution of the Gafchromic film dosimeter is better than 0.01 Gy.To avoid the effect of scattered rays,the cutting film is recommended for testing dose response non-uniformity.
