非晶硅电子射野影像系统与ArcCHECK在直肠癌容积旋转调强剂量验证中的应用

A-Si EPID and Arc CHECK dosimetric verification for VMAT of rectum cancer

目的:比较非晶硅电子射野影像系统(a-Si EPID)与旋转照射剂量验证仪器(Arc CHECK)在直肠癌容积旋转调强(VMAT)剂量验证中的应用。方法:随机选取20例直肠癌VMAT病例,分别设计a-Si EPID与Arc CHECK的验证计划,并在UNIQUE加速器上进行验证。采用γ分析方法(3 mm,3%)比较两种不同验证工具的相对剂量与绝对剂量通过率、X和Y方向的profile。结果:Arc CHECK的绝对剂量通过率为(97.73±1.98)%,相对剂量通过率为(96.96±2.34)%;aSi EPID的绝对剂量通过率为(97.58±1.88)%,相对剂量通过率为(98.13±1.47)%。X、Y方向的profile理论值与实测值很相近,理论剂量分布图与实测计算剂量分布图在高低剂量点分布上重合度较高。结论:Arc CHECK和a-Si EPID的验证结果在剂量学上没有明显差异,两者在直肠癌VMAT剂量验证中都是可行的,但a-Si EPID操作简单、使用方便、显示剂量即时,可以更便捷地进行VMAT剂量验证。

Objective To compare the amorphous silicon electronic portal imaging device（a- Si EPID） and Arc CHECK dosimetric verification for volumetric modulated arc therapy（VMAT） of rectum cancer. Methods Totally, 20 patients with rectum cancer were randomly selected. The verification plans of a- Si EPID and Arc CHECK were respectively designed,and the plans were performed on UNIQUE accelerator. The relative dosage pass rate, absolute dosage pass rate, and the profile of X and Y directions between the two different verification tools were compared by using Gamma method（3 mm,3%）. Results The absolute dosage pass rate and relative dosage pass rate of Arc CHECK were respectively（97.73±1.98）%and（96.96±2.34）%, and those of a-Si EPID were respectively（97.58±1.88）% and（98.13±1.47）%. The theoretical values of the profile of X and Y directions were close to the measurements, and the high and low dose point distribution of theoretical dose distribution diagram had high coincidence with that of measured dose distribution diagram. Conclusion No significant differences were found between Arc CHECK and a- Si EPID verification, both of which are feasible for dosimetric verification of VMAT of rectum cancer. But a- Si EPID which is easy to operate, showing the dosage immediately can be used more conveniently in the dosimetric verification of VMAT.