一种医用直线加速器多叶光栅的位置检测系统

摘要

针对医用直线加速器多叶光栅提出一种直接的位置检测设计方案.首先,对光栅叶片前端使用标记物进行标记,将摄像机固定于多叶光栅下等中心位置并对相机进行标定;其次,使用摄像机获取多叶光栅运动的视频图像,并通过通用串行总线传输到个人计算机端;然后,利用相机的标定参数对图像进行矫正,并计算叶片实际位移与图像像素移动个数的比例,最终通过该比例以及像素移动个数来计算标记点的实际位移量.在仿真实验中,使用该方法对38个感兴趣点分别移动2、4、7、11 cm位置进行测试,摄像机可以准确捕捉到38个测试点,结果显示感兴趣测试点位置测算准确,误差均在1 mm以内,满足系统要求.本研究有望为放疗临床治疗过程中多叶光栅自检提供一定的指导.%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.