医科达ComPact电子直线加速器小机头外挂多叶光栅——引发机架故障分析和改进

Failure Analysis and Improvement of A Mini-head for Layering Multi-leaf Grating on A Medical Computerdriven ComPact Electron Linear Accelerator

医用电子直线加速器是肿瘤放射治疗的一种主要设备。直线加速器产生的高能X射线通过束流系统、均整器和准直器形成具有一定大小、规则的照射野,照射肿瘤靶区,在临床肿瘤放射治疗中,肿瘤的大小形状是不规则的,为了满足肿瘤治疗区域很高的治愈剂量且周围正常组织接受很少的损伤剂量目的,在治疗时用铅档对形状规则的射野进行遮挡,形成肿瘤大小、形状一致的照射野,从而达到治疗肿瘤保护正常组织的目的。遮挡技术经历了挡铅、外置多叶光栅、内置多叶光栅的发展历程。由于外置光栅大多并非厂家设计,外挂光栅会引起设备的结构变化,导致意想不到的故障,特别是与机头连接的机架运动方面受影响而引发故障。

Medical electron linear accelerator is a kind of main equipment of radiotherapy for tumor.The high-energy x-ray produced by linear accelerator forms a regular radiation field through beam system,homogenizer and collimator,which irradiates the target area of tumor.The size and shape of tumor are irregular in clinical radiotherapy,in order to meet the goal of high cure dose in tumor treatment area and little damage dose to normal tissues around,the regular shaped radiation field is blocked by lead shield to form the same size and shape radiation field of tumor,in order to achieve the goal of treating tumor and protecting normal tissue.The shielding technology has experienced the development course of shielding lead,external multi-leaf grating and internal multi-leaf grating.Because most of the external grating is not designed by the manufacturer,the external grating will cause the change of the structure of the equipment,which will lead to unexpected faults,especially the motion of the frame connected with the head.