直肠癌术后不同体位调强放疗的研究

目的比较直肠癌术后俯卧位和仰卧位调强放疗（IMRT）照射，靶N（CTV、PTV），小肠、膀胱、股骨头的体积一剂量关系，探讨直肠癌术后IMRT放疗的合适体位。方法统一规定直肠癌术后辅助性放疗的临床肿瘤体积（CTV）范围，设定计划靶体积（PTV）为CTV~I＂扩0．5～1．0cm。对14例直肠癌术后俯卧位和仰卧位IMRT计划进行剂量学评估，比较2种体位IMRT~术下靶区．小肠，膀胱，股骨头受照射剂量一体积关系。结果直肠癌术后放疗采~IMRT技术时，仰卧位和俯卧位时的靶N（CTV45，CTV50．PTV45、PTV50）、小肠（平均剂量Dmean、V20，V30、V40、V45、V50）、膀胱（平均剂量Dmean．V30、V40，V50）及股骨头（平均剂量Dmean．V40，V50）均无统计学差异炒0．05。结论直肠癌术后IMRT时，无有孔腹板条件下，仰卧位放疗，较之俯卧位，不会导致靶区剂量分布变劣及小肠、膀胱、股骨头等正常结构受照射的剂量、体积增加，并有较好的重复性和舒适度，值得采用。

Study of Intensity-modulated Radiotherapy in Supine and Prone Position for Postoperative Rectal Cancer

Objective To retrospectively study whether there were any differences among rectal cancer patients who accepted postoperative adjuvant intensity-modulated radiotherapy（IMRT） in supine and prone position.Methods 14 patients with rectum cancer accepted postoperative adjuvant IMRT,6 of them in traditional prone position,the other 8 in supine position.The dose distribution of clinic target volume（CTV） and planning target volume（PTV） at 45Gy and 50Gy,the mean dose of bowel and the volume receiving dose of 20Gy,30Gy,40Gy,45Gy,50Gy,the mean dose of bladder and the volume receiving dose of 30Gy,40Gy,50Gy,the mean dose of bilateral femoras and the volume receiving dose of 40Gy,50Gy were evaluated by means of dose--volune histogram （DVH） respectively.Results No significant differences were noted between prone and supine position groups on dose distribution of CTV and PTV and dose-volume relationship of bowel,bladder ,femoras.Conclusion postoperative adjuvant IMRT in supine position for rectal cancer seems comparative to that in prone position regarding to both the target coverage and the tolerance of bowel, bladder, remoras.