A method for determination of dwell position offset of ring applicator using GafchromicTM EBT3 film and ImageJ software
10.3760/cma.j.issn.0254-5098.2018.11.013
- VernacularTitle:一种采用辐射显色胶片EBT3和ImageJ软件确定环形施源器驻留位置偏移量的方法
- Author:
Hongfu ZHAO
1
;
Zhipeng ZHAO
;
Dongmei HAN
;
Guanghui CHENG
Author Information
1. 吉林大学中日联谊医院放疗科
- Keywords:
Brachytherapy;
Applicator reconstruction;
GafchromicTM EBT3;
ImageJ
- From:
Chinese Journal of Radiological Medicine and Protection
2018;38(11):865-869
- CountryChina
- Language:Chinese
-
Abstract:
Objective To report a simple method for determination of dwell position offset of ring applicator using GafchromicTM EBT3 film and ImageJ software. Methods In the dummy plan, this study reconstructed the ring applicator point by point manually according to the MR line marker, the most distal reconstruction point was at the end of marker, set the offset to zero. The first, eleventh, and twenty-third dwell positions were activated with the step length of 2. 5 mm. A setup image was designed to immobilize the ring applicator. The setup image was composed of two perpendicular thin lines and a circular with a diameter of 16 mm. GafchromicTM EBT3 film was fixed behind the setup image by plastic tapes. After irradiation, a ruler was put on the bottom of the irradiated film as a plotting scale. Photos were taken with the help of a vertical camera using a tripod. The file was imported into ImageJ software and the coordinate values were obtained by semi-automatic recognition of the center of exposure area. The test was repeated five times at one week interval to evaluate the uncertainty. For every time, each dwell position was measured five times. Results The angle between the radius of the first dwell position and the x-axis was 43° in the dummy plan, and (46. 8 ± 0. 9)° for actual measurement. The offset was 0. 9 mm for the ring applicator combined with the MR according to calculation. The distances between the first,the eleventh and the twenty-third dwell positions and the center of the ring were ( 12. 9 ± 0. 1 ) mm, ( 12. 5 ± 0. 1 ) mm, (12. 4 ± 0. 1) mm, respectively. Conclusions Using GafchromicTM EBT3 film and the ImageJ software is a simplified method to validate the dwell position offset of the ring applicator.
