由于三维放疗方法的日益普及,多叶准直器(muhi-leaf collimator,MLC)的使用越来越多.笔者在实际工作中遇到1例连线方面故障,现介绍如下.一、故障现象在维修机器其他故障时,对MLC的B面电路板进行了拆卸,复位后对MLC进行自检.开始时所有的叶片都回到了零位,只有B31叶片没用收回,工作站电脑提示Carriage已运动到极限位置,自检中断停止.用Service panel单独操作B31,进退都无反应.将B31电机拆下,保持接线正常连接,仍用Service panel操作,发现电机不转。

[Objective] To present a more effective way to determinate the target volume in electron beam irradiation while using three-dimensional treatment planning system.[Methods] Contoured the target volume according to the images from CT simulation,and designed the electron beam irradiation field by using 3DTPS.Calculated the shifting coordinate of irradiation field based on the original coordinate.Installed the applicator with the leaden block of electron beam onto the accelerator.Turned on the lamp field and marked the cross line on the plate.A foam mould which was marked with filed centre and direction should be cutted based on the DR image from TPS.The leaden block would be made on a premise that the cross lines on the plate and the foam were coincident.Evaluated the feasibility of this method by radiotherapy verification.[Results] The offset degree of target centre was less than 2.2 mm,also the maximum deviation is less than 1.7 mm.[Conclusion] The method that coincide the irradiation field centre and the centre from TPS can solve the problem of target area's variation.Also the method can ensure the process of electron irradiation going smoothly.

故障现象 在没有安装托架和限光筒的情况下,旋转机架,准直器上的Reset按钮红灯被点亮,使机架旋转、床升降等运动被锁住,按Reset按钮不能恢复,若一直按住Reset按钮不放,能够恢复各运动.