瑞迪RD/DB碳纤维定位体架质量保证

Quality Assurance for RuiDi RD/DB Carbon Fiber Immobilization Body-Frame

目的:对新购进瑞迪RD/DB碳纤维定位体架进行全面检验,建立相应的质量保证体系。方法:(1)肉眼外观检查体架一般情况;使用钢卷尺测量外表坐标刻度的准确性。(2)在模拟机下使用激光灯检测左右Y轴,Z轴外表刻度的一致性。(3)使用直线加速器6MVX-线,固体水模及0.66cc电离室测量体架穿射因子随测量深度及机架角度变化情况。(4)使用模体模仿实际情况检测内置坐标同外表刻度的一致性。结果:卷尺测量右侧Y轴,右侧Z轴及X轴均无差异;Y轴外表坐标刻度400～100范围左侧较右侧数值最大范围小1mm,800～400间无差异;Z轴左右对应无差异;X轴100外表刻度对应内置坐标之定位基准线;穿射因子随测量深度和机架角增加而增加,机架角15°以前变化较缓,后变化加快;1mm,3mm,5mm,7mm层厚CT扫描传入TPS重建并计算得等中心坐标同预设坐标均有差异,最大值<1.8mm。结论:实际检测结果符合临床治疗要求,但仍须对新购体架作全面验证,实际计算出等中心坐标需经模拟机或EPID验证后方能作为治疗坐标使用。

Objective： To check the new-purchased RuiDi RD/DB carbon fiber immobilization body-frame to set up the related quality assurance system. Methods： （1）The RuiDi body-flame＇s appearance was evaluated objectively and its outside coordinates was verifide measured to check their accuracy by using a steel ruler. （2）The agreement of outside coordinates for Y-axis and Z-axis were checked by using simulator laser. （3）The body-flame transmission factor was measured in solid water phantom using 0.6 cc ion chamber for 6 MV X-ray .Absorbed dose fluctuation with different measured depth and gantry angle was also measured. （4）The agreement of outside and inner coordinates system was also verified by simulating actual treatment process in which the solid water phantom was also used .Results： The scale of right outside Y, Z, X coordinates are accurate. The left outside Y-axis scale is 1 mm shorter than the right one between 400-100 while there is no difference between them for the range 400-800.The transmission factor increases with the measured depth and gantry angle＇s increase.It changes slowly with the gantry angle less than 15 degree.The CT studies of 1 mm,3 mm,5 mm,7 mm slices were transfered to the TPS to be reconstructed. There are differences between all the measured ISO-coordinates and the preset coordinates, but the maximum error is less than 1.8 mm. Conclusions： The checked results for RuiDi RD/DB carbon fiber immobilization body-frame meet our clinical radiotherapy requirement after recalibrated. However, Every newly purchased immobilization body-frame should be checked comprehensively .The actual measured treatment ISO-coordinates can not be used until they＇re verified by using simulator or EPID.