不同铅门模式下高危分期前列腺癌螺旋断层放射治疗剂量学比较

【摘要】目的:探讨高危分期前列腺癌行螺旋断层局部照射同步盆腔淋巴结照射时，不同铅门模式下（静态和动态）靶区及危及器官的剂量学特点。方法:选取8例需行局部照射同步盆腔淋巴结照射的高危分期前列腺癌患者，分别设计铅门宽度为1.050、2.512和5.050 cm的3组静态铅门计划（F1.050、F2.512、F5.050）以及宽度为2.512、5.050 cm的2组动态铅门计划（D2.512、D5.050）。比较不同计划设计下靶区及危及器官的剂量分布、剂量体积直方图以及出束时间和机器跳数等。结果:在不同铅门模式下，靶区剂量学差异几乎无统计学意义（P>0.05）。而在膀胱、直肠以及股骨头的剂量学比较上，当铅门宽度相同时，动态铅门计划几乎与静态铅门计划相当；当铅门宽度不同时，静态铅门计划远优于比之大一档宽度的动态铅门计划。在非肿瘤组织的剂量辐射比较上，动态铅门技术均体现出了明显的剂量学优势。在计划实施效率方面，各计划平均机器跳数、平均出束时间均随F5.050、D5.050、F2.512、D2.512、F1.050顺序依次递增。结论:对于需行局部照射同步盆腔淋巴结照射的高危分期前列腺癌患者，动态铅门优势有限且在一定程度上降低了计划的实施效率。

Dosimetric study of helical tomotherapy for high-risk prostate cancer under different jaw modes

Objective To explore the dosimetric characteristics of target areas and organs-at-risk(OAR)in high-risk prostate cancer patients treated with helical tomotherapy for local irradiation combined with pelvic lymph node irradiation under different jaw modes(static state and dynamic state).Methods Eight patients with high-risk prostate cancer scheduled for local irradiation combined with pelvic lymph node irradiation were enrolled in this study.Three groups of static plans with the jaw widths of 1.050,2.512 and 5.050 cm(F1.050,F2.512 and F5.050)and two groups of dynamic plans with the jaw widths of 2.512 and 5.050 cm(D2.512 and D5.050)were designed for each patient.The dose distributions and dose-volume histograms of target areas and organs-at-risk,delivery time and monitor units were compared among different plans.Results Under different jaw modes,the dosimetric difference of target areas was trivial,without statistical differences(P>0.05).For the dosimetric comparison of rectum,bladder and femur head,with the same jaw width,dynamic jaw plan was almost the same as static jaw plan;however,static jaw plan was obviously superior to dynamic jaw plan with larger jaw width when the jaw width was different.Dynamic jaw technique had obvious dosimetric advantages in the dose to normal tissues.The average monitor units and average delivery time of 5 plans were increased with the order of F5.050,D5.050,F2.512,D2.512 and F1.050.Conclusion For patients with high-risk prostate cancer scheduled for local irradiation and pelvic lymph node irradiation,dynamic jaw mode has limited advantages and reduces the delivery efficiency.