直肠癌术后三维适形放疗和三种共面分野调强计划设计的对比分析赵钦发1（1.监利县人民医院肿瘤科，湖北监利433300）摘要：目的：探讨直肠癌术后三维适形放疗（3D-CRT）与三种共面设野调强（IMRT）放射治疗技术计划设计的靶区和正常组织器官的受照剂量的差异，为直肠癌的术后放疗方法的临床选择提供理论依据。
方法：选取10例直肠癌术后患者，经过增强CT扫描后，在Ecilpse计划系统医生工作站，由同一个医生完成对靶区和正常组织器官的勾画，处方剂量46.8Gy（1.8*26)。
分别对病人进行三野（009002700）三维适形，五野（8504500031502750），七野（85060030000330030002750）和九野（1000750500250003350310028502600）共面调强计划设计，计算靶区的均匀指数（HI），适形指数（CI），最大照射剂量，最小照射剂量，平均照射剂量和危及正常组织器官的照射量的体积，然后进行对比分析。
结果:（1）靶区的适形指数五野，七野，九野IMRT均优于3D-CRT。
（2）对危及器官，小肠V30，V40，膀胱V30，V40，股骨头V30，V40，三种共面调强方法明显优于3D-CRT。
（3）三种共面调强在适形指数上，七野，九野IMRT略优于五野IMRT。
在对危及器官的剂量体积比较无统计学意义。
结论:直肠癌术后的辅助放疗中，共面调强中无论从靶区的适形指数，对正常组织器官的保护均优于3D-CRT。
五野调强相对七野，九野在治疗时间，机器磨损，剂量散射有一定优势。
共面五野IMRT值得在临床上推广。
关键词：直肠癌；三维适形；调强放射治疗；Dosimetric study of postoperative3-dimensional conformal radiotherapy and intensity-modulated radiotherapy for rectal cancerAbstract:ObjectiveAbstract:Objective::To compare the difference of the dose distribution in clinical target volume andMethods::Ten postoperative Ten postoperative patients with organs at risk radiotherapy of rectal cancer.Methodsrectal cancer were selected to undergo CT Scan planning target volume and OAR contouring.3-field（009002700）dimensional conformal,5-field（8504500031502750）,7-field（85060030000330030002750）and9-field（1000750500250003350310028502600）IMRT planning was performed for each patientwith a prescribed dose of46.8Gy.The homogeneity index,conformal index,maximum dose,minimumResults:: dose,mean dose and irradiated volume of OAR were calculated and the results were compared.Results(1)5-field IMRT,7-field IMRT and9-field IMRT plans had a significant better conformity index(CI)ofPTV compared with3D-CRT.(2)Compared with3D-CRT plans,V30,V40,of the bladder,V30,V40,of thesmall bowel,as the femoral head in the coplanar IMRT plans were all significantly reduced but showedno significant differences among the IMRT plans.(3)9-field and7-field has a little better conformityConclusion::IMRT plans is superior to3D-CRT plan in terms of the index than5-field-IMRT Conclusionconformity index full of the PTV and sparing the bladder and small bowel.7-field and9-field IMRT doa little benefits than5-field IMRT,and5-field IMRT can significantly reduce the treatment time andcosts．Keywords:rectal cancer;3-dimensional-radiotherapy;intensity-modulated radiotherapy;直肠癌（rectal cancer）发生于直肠齿状线以上至乙状结肠起始部之间，是消化道常见的肿瘤。
