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目的 探索直肠癌术后调强放疗患者膀胱充盈与排空体积的改变对计划靶区及正常组织受照射剂量的影响,为直肠癌术后临床IMRT提供参考依据.方法 19例病理证实的直肠癌术后患者膀胱充分充盈状态,行CT扫描;相同CT扫描条件下行膀胱充分排空状态扫描;在治疗计划系统中,勾画膀胱充分充盈扫描图像的肿瘤靶区和周围正常组织;勾画膀胱排空扫描图像的肿瘤靶区和周围正常组织;并进行比较.结果 膀胱充分充盈与排空状态,计划靶区、股骨头受照射剂量,皆没有明显变化(P＞0.05).膀胱充盈与排空两种状态下患者正常组织膀胱、小肠、结肠受照剂量P值分别为0.019、0.022和0.037,其差异都有统计学意义(P＜0.05).结论 直肠癌术后调强放疗,与排空相比膀胱充盈能减少膀胱,小肠及结肠的受照射体积和受照剂量,对靶区股骨头无影响.“,”Objective In order to study how the variation of bladder volume impacts on the distribution of the irradiated dose of planning target volume and normal tissue volume in intensity modulated radiation therapy(IMRT),and to provide reference material for rectal cancer undergoing postoperative IMRT.Methods 19 pathologically confirmed idiopathic patients are taken computed tomography (CT) scan under two situations-bladders full and bladders empty.Making use of those CT images,we delineate their planning target volumes and surrounding normal tissues for the two situations in treatment planning system (TPS).The results are compared.Results Contrasting bladder full and empty situations,we find that the dose of PTV and femoral head do not variate obviously (P ＞ 0.05).However,the dose statistical results of bladder,bowl and colon are 0.019,0.022 and 0.037 (P ＜ 0.05).These differences are obvious on statistics.Conclusion In rectal cancer undergoing postoperative IMRT,compare to bladder empty situation,the irradiated volume and dose of bladder,bowl and colon reduce obviously when bladder is full.But the impact of PTV and femoral head could be ignored in these cases.