直肠癌术后造口患者调强放疗计划的角度优化剂量学研究

The Study of Beam Angle Optimization in IMRT Plans for Postoperative Rectal Cancer Patients

[目的]探讨在直肠癌术后造口患者术后放疗中,射野角度优化对调强放疗计划剂量分布及肠造口受量的影响。[方法]随机选取10例直肠癌术后造口患者,采用6野角度优化计划与7野角度均分调强计划进行比较,统计分析靶区(PTV)剂量分布及机器跳数、危及器官的受照剂量,分析不同计划的剂量学差异。[结果]与7野均分计划组相比,6野角度优化计划组PTVD_(max)、D_(mean)、D_(min)、均匀指数差异无统计学意义(P>0.05);PTV适形指数稍劣于7野均分计划组(t=3.359,P<0.05);6野角度优化计划的肠造口D_(max)、D_(mean)均有显著降低(P<0.001),而小肠(V_(40)、V_(30))、膀胱(V_(40)、V_(30))、造口侧及对侧股骨头(V_(30))两组差异均无统计学意义;2组Mu数相似,差异无统计学意义(t=0.432,P>0.05)。[结论]直肠癌术后造口患者放疗6野角度优化后的调强计划,降低了肠造口的受照剂量,基本保持与7野均分计划相当的靶区和危及器官的剂量学结果。

[Objective] To explore the effect of beam angle optimization on intensity modulated radiation therapy（IMRT） plan in postoperative rectal cancer patients with stoma. [Methods] Ten postoperative rectal cancer patients with stoma were randomly enrolled. 6 beams angle optimization（6WO） was compared with 7 equiangular-spaced beams（7WD） IMRT plans. PTV dose distribution,monitor unit（Mu） and dose of organ at risk were calculated and dosimetric difference between each plans were analyzed. [Results] There were no significant dosimetric differences of PTVD_（max）,D_（mean）,D_（min） and comfort index（CI） compared 6WO with 7WD plan（P0.05）. 7WD plans showed significant advantage in PTV homogeneity index（HI）. 6WO plan showed significant lower stoma D_（max） and D_（mean） compared with 7WD plan（P0.001）. But there was no significant difference in small intestine（V_（40）,V_（30））,bladder（V_（40）,V_（30））,femur（V_（30）） and Mu among two different plans（P 0.05）. [Conclusions] In postoperative rectal cancer patients with stoma receiving radiotherapy,6beams angle optimization IMRT plan could reduce stoma dose and nearly keep the same target volume and dose for organ at risk with 7 equiangular-spaced beams plan.