基于Varian加速器海马保护全脑放疗剂量学技术比较

Dosimetric study of hippocampal protective whole brain radiotherapy based on Varian accelerator

目的通过比较Varian加速器共面动态调强dIMRT与共面VMAT计划在海马保护全脑放疗(WBRT)中剂量学差异,为临床放疗计划选择提供一种依据。方法 10例海马保护WBRT患者,每名患者均设计dIMRT与VMAT计划,比较两者靶区剂量、危及器官剂量和机器跳数的差异;。结果 2种技术计划PTV V_(30 Gy)、D_(98%)和D_(2%)均符合RTOG 0933标准,对于PTV HI VMAT组优于dIMRT组(P=0.004)。海马剂量dIMRT组优于VMAT组,但均未达到RGOT 0933标准:dIMRT组与VMAT组海马D_(max)均值分别为18.44 Gy和19.30 Gy,有统计学差异(P=0.004);海马D_(min)均值分别为10.03 Gy和10.77 Gy,有统计学差异(P=0.013);海马D_(mean)均值分别为14.20 Gy和15.12 Gy,有统计学差异(P=0.002)。晶体、眼球和视神经剂量均符合RTOG 0933标准,dIMRT组也明显优于VMAT组,均P=0.000。VMAT组治疗时间低于dIMRT组。结论 Varian dIMRT相比VMAT控制海马剂量和保护晶体更有优势,但VMAT组PTV HI和治疗效率更高。

Objective The purpose of this study is to provide a reference for the selection of clinical radiotherapy plan by comparing the difference of dosimetry between coplanar dynamic intensity modulation dIMRT and coplanar VMAT plan in hippocampal protective whole brain radiotherapy(WBRT).Methods 10 patients were selected whose hippocampal were protected by WBRT,dIMRT and VMAT plans were designed for each patient,the differences of target dose,organ-endangering dose and machine hop count were compared between the two groups.Results The two technical plans PTV V_(30) Gy,D_(98%) and D_(2%) all meet the standard of RTOG 0933,which is better than the dIMRT group for the PTV HI VMAT group(P=0.004).The hippocampal dose of dIMRT group was better than that of VMAT group,but it did not meet the standard of RGOT 0933.The average D_(max) of hippocampus in dIMRT group and VMAT group was 18.44 Gy and 19.30 Gy,respectively(P=0.004).The average value of hippocampal Dmin was 10.03 Gy and 10.77 Gy,respectively(P=0.013),and the mean value of hippocampal Dmean was 14.20 Gy and 15.12 Gy,respectively(P=0.002).The doses of lens,eyeball and optic nerve all met the standard of RTOG0933,and the dose of dIMRT group was significantly better than that of VMAT group(P=0.000).The treatment time in VMAT group was significantly lower than that in dIMRT group.The treatment time in VMAT group was significantly lower than that in dIMRT group.Conclusion Varian dIMRT has more advantages in controlling hippocampal dose and protecting lens than VMAT,but PTV HI and treatment efficiency are higher in VMAT group.