Abstract

Info

Title:: A position detection system for multi-leaf collimator on medical linear accelerator

Author(s):: ZU Chongyang1; YU Gang1; ZHANG Chuanyi1; LU Yukun1; QIU Qingtao1; HOU Yong2; LI Dengwang1; 1. Shandong Province Key Laboratory of Medical Physics and Image Processing Technology; School of Physics and Electronics, Shandong Normal University, Ji’nan 250000, China; 2. Department of Radiotherapy, Qianfo Mountain Hospital of Shandong Province, Ji’nan 250000, China

Keywords:: ; accelerator; multi-leaf collimator; open source computer vision library; position detection; camera calibration

Abstract:: A direct design proposal is proposed for the position detection system of multi-leaf collimator on medical linear accelerator. Firstly, appropriate markers are made at the front end of the grating blade, and the vidicon is fixed on the center of the multi-leaf collimator, and the camera is calibrated. Then, use the vidicon to obtain the video images of multi-leaf collimator movement, and send them to the PC end through USB 2.0. Subsequently, the obtained images are corrected using the calibration parameters, and the ratio of the actual displacement of blade and the number of image pixels moved is calculated. Finally, the actual displacement of the marked points is determined based on the calculated ratio and number of image pixels moved. During the simulation test, 38 interested points are moved over an distance of 2, 4, 7 and 11 cm, respectively, and the test results showed that the vidicon accurately capture the 38 test points. The position calculation of the interested points utilizing this method is accurate with the error less than 1 mm, which meets the requirements of the system. This research is expected to provide some guidance for the self-inspection of multi-leaf collimator in the radiotherapy.