直肠癌盆腔放疗后肠受照射影响因素的研究

目的 评价体位、性别、手术、膀胱充盈状态对直肠癌放疗后肠受照射的影响。方法36例直肠癌患者被研究，盆腔放疗采用1后2侧野三维适形放射治疗（3DCRT）的方法，处方剂量为50Gy。利用每个计划的剂量．体积直方图（DVH）对盆腔内肠的受照剂量和体积进行分析。结果膀胱充盈差和好时肠受照射的平均剂量分别是23．8和18．3Gy（P=0．004），V45高剂量受照体积分别是15．7％和7．8％（P=O．004）；体位仅对肠V15，低剂量受照体积有显著影响；性别对肠受照射的最大剂量和V15，有显著影响；手术对肠受照射的平均剂量有显著影响，分别是术前19．0Gy和术后22．5Gy（P=0．015）；在仰卧或俯卧、术前或术后膀胱充盈好时均比差时肠受照射剂量要低或体积要小。膀胱充盈好和差时肠受到高剂量照射的体积V4，在俯卧位分别是15．3％和7．4％（P=0．023），术后分别是14．1％和7．2％（P=0．014），差异有统计学意义。结论 患者治疗体位、性别、手术对盆腔内肠受照射剂量和体积有一定的影响，膀胱充盈状态有显著影响。

Analysis of influence factors on the volume of pelvic bowel irradiated for rectal cancer

Objective To evaluate influence of prone supine position, gender, operation, bladder distension on bowel irradiated for patients with rectal cancer during pelvic radiotherapy. Methods 36 patients with rectal cancer were investigated. Treatment plans were created with three dimensional treatment planning system. The dose and volume of bowel irradiated were analyzed according to dose-volume histograms (DVH) for every patient. The prescribed dose was 50 Gy. Results The extent of bladder distension significantly influenced the mean doses and the V₄₅ high dose volumes of bowel irradiated. The treatment position and gender significantly influenced the V₁₅ low dose volume of bowel irradiated, the operation significantly influenced the mean doses of bowel. Either prone and supine position, or preoperative and postoperative, the doses of bowel irradiated for good bladder distension were lower and the volumes were smaller than that for bad bladder distension. The V₄₅ high dose volume of bowel irradiated for bad and good bladder distension at prone position were 15.3% and 7.4%(P=0.023),respectively, and at postoperative 14.1% and 7.2%(P=0.014), respectively. Conclusions The doses and volumes of pelvic bowel irradiated were significantly influenced by the extent of bladder distension, and partly influenced by the prone/supine position, gender and operation.