故障现象　故障发生时 ,伽玛刀治疗床上安装的是 4ｍｍ准直器 ,现象为机器能正常开机 ,屏蔽门正常启动 ,治疗床也能顺利到达目的位置 ,内外准直器吻合度符合 0 .1ｍｍ的准直器平衡要求 ,机器能按照设定的时间要求完成一次空治疗 ,但是 ,治疗完毕退床时 ,却出现报警灯急速闪烁 , Fault phenomenon When the fault occurs, the gamma knife is equipped with a 4mm collimator on the treatment bed. The phenomenon is that the machine can normally start up, the screen door starts normally, the treatment bed can reach the target position smoothly, and the degree of coincidence of the internal and external collimators is compliant with 0.1mm. The collimator balance requirements, the machine can complete an empty treatment according to the set time requirements, but when the treatment is completed, the alarm light flashes rapidly.