WS531-2017《螺旋断层治疗装置质量控制检测规范》的实施及评价

Implementation and evaluation of WS531-2017 "specification for testing of quality control in helical tomotherapy unit"

目的:依据WS531-2017《螺旋断层治疗装置质量控制检测规范》,对浙江省首台螺旋断层治疗系统(Tomotherapy,TOMO)进行年度系统稳定性检测,进一步规范质量控制操作,明确系统的各项性能,保证临床放射治疗的准确实施。方法:利用8通道计量仪(TomoElectrometer)、电离室A1SL(Standing Imaging, USA)和A17(Standing Imaging, USA)、圆柱形模体(Cheese Phantom)、等效矩形固体水、二维水箱、EBT3胶片和Vidar胶片分析仪,按照WS531-2017要求,对TOMO的10个关键指标进行检测。结果:设备静态输出剂量偏差为-0.6%;旋转输出剂量偏差为1.4%。射线质与计划值偏差为0.8%。射野横向剂量曲线的对称性为-1.2%。射野纵向剂量曲线半高宽偏差为0.7 mm。多叶准直器横向偏移为-0.6 mm。绿激光灯在虚拟等中心横断面偏移为0.08 mm、矢状面和冠状面的偏移为0.2 mm;红激光灯指示偏差-0.4 mm。治疗床的移动偏差为0.3 mm。治疗床和机架旋转同步性偏差为-0.6 mm。结论:TOMO的10项关键指标均满足WS531-2017的评价标准,建议TOMO年检时适当增加必要检测项目,如MVCT图像质量检测等,以确保系统的正常工作及良好的稳定性。

Objective To perform an annual test on the system stability of the first helical tomotherapy unit(Tomotherapy,TOMO)in Zhejiang province according toWS531-2017"specification for testing of quality control in helical tomotherapy unit",and to further standardize the quality control operation,understand the properties of the system and ensure the accurate implementation of clinical radiotherapy.Methods According to the requirements of WS531-2017,8-channel measurement instrument(TomoElectrometer),ionization chamber A1SL(Standing Imaging,USA)and A17(Standing Imaging,USA),cylindrical phantom(Cheese Phantom),equivalent rectangular solid water,two-dimensional water tank,EBT3 film,and Vidar film analyzer were used to detect 10 key indicators of TOMO.Results The static output dose deviation was-0.6%,and the rotational output dose deviation was 1.4%.The difference between beam quality and planned value was 0.8%.The symmetry of the horizontal dose curve of the radiation field was-1.2%;and the full width at half-maximum deviation of the longitudinal dose curve of the radiation field was 0.7 mm.The horizontal offset of multi-leaf collimator was-0.6 mm.The green laser offset in axial plane,sagittal plane and coronal plane were 0.08,0.2 and 0.2 mm to the virtual isocenter.The red laser offset was-0.4 mm.The movement deviation of the treatment couch was 0.3 mm;and the synchronous deviation of the rotation of the treatment couch and gantry was-0.6 mm.Conclusion All 10 key indicators of TOMO meet the requirements of WS531-2017.Some necessary testing items,such as MVCT image quality verification,should be added to the annual TOMO quality control in order to ensure the good stability and normal working of system.