调强适形放疗结合俯卧位减少小肠受照剂量的临床评价

目的:评价盆腔调强适形放射疗法(IMRT)结合俯卧位加置腹部平板治疗妇科恶性肿瘤时是否可以更大程度上减少小肠的受照剂量.方法:13例妇科恶性肿瘤患者,其中子宫颈癌10例,子宫内膜癌3例,均给予盆腔放射治疗.放疗前均行仰卧位和俯卧位腹、盆部CT扫描.正常组织兴趣区包括小肠、大肠和膀胱.IMRT治疗方案使用180°弧形调强技术和340°弧形调强技术.运用t检验分别比较小肠、大肠和膀胱在仰卧位和俯卧位时的受照剂量.结果:运用180°弧形调强技术时,俯卧位加置腹部平板有助于小肠的旷置,小肠的受照剂量在俯卧位比仰卧位减少12～26 Gy;运用340°弧形调强技术时,俯卧位小肠受照剂量减少不明显;大肠和膀胱在仰卧位和俯卧位的受照剂量差异均无显著性意义.结论:妇科恶性肿瘤盆腔180°弧形调强技术结合俯卧位加置腹部平板的方法可以减少小肠的受照剂量,具有临床实用价值.

Combination of Prone Position and Intensity Modulated Radiation Therapy for Reduction of Small Bowel Radiation Dose LI

Objective:To evaluate if the combination of prone position on a belly board and intensity-modulated radiotherapy (IMRT) further reduces the radiation dose to small bowel in pelvic RT for gynecologic malignancies.Methods:Conformal pelvic RT were performed in 13 patients with gynecologic malignancies,10 cervical cancer and 3 endometrial cancer,in both the supine position and prone position on a belly board.IMRT plans consisted of a limited arc technique (180 arc length),and an extended arc technique (340 arc length).Normal tissue regions of interest included small bowel,large bowel and bladder.Dose and volume for normal tissue structures were traced and compared between supine and prone plans using the paired t-test.Results:For the limited arc technique,prone position using a belly board device improved small bowel sparing.Analysis of the results showed a 12~26Gy reduction of volume of small bowel irradiated in prone position compared to the supine position.With the extended arc technique,a small advantage of the prone position remained.Large bowel and bladder dose showed no significant differences between prone and supine position with either technique.Conclusion:Prone positioning on a belly board decreases the small bowel dose in gynecologic pelvic IMRT,and the magnitude of improvement depends on the limited arc IMRT technique used.