摘要
目的:比较宫颈癌盆腔照射螺旋断层放射治疗(Helical Tomotherapy,HT)计划与七野-静态调强放疗(7F-IMRT)计划的靶区和危及器官的剂量学差异。方法:选取2015年3月~2017年10月行HT治疗的25例宫颈癌患者,均采用俯卧位,憋尿状态。分别进行HT和7F-IMRT两种计划设计,比较两种计划模式之间靶区和危及器官之间的剂量学参数及机器输出跳数。结果:(1)计划靶区(PTV):HT组CI和HI均优于7F-IMRT组,具有统计学差异(0.898±0.017 vs 0.834±0.013,P<0.001;0.062±0.012 vs 0.109±0.019,P<0.001);HT组PTV的D_1、D_2均低于7F-IMRT组(P<0.001),D_(mean)、D_(98)、D_(95)均较7F-IMRT组高(P=0.048,P<0.001,P=0.015)。(2)对于正常组织,HT组小肠、结肠、直肠和膀胱的D_(max)、D_(mean)、V_(30)、V_(40)以及直肠V_(50)均显著低于7F-IMRT组(P<0.001,P<0.001,P<0.001,P=0.001,P=0.006),其余V_(50)略低,无统计学差异(P=0.130);HT组双侧股骨头V_(25)、D_5、D_(mean)、D_(max)也显著低于7F-IMRT组(P<0.001);但是,HT组的机器输出量明显高于7F-IMRT组。结论:HT计划在适形度、均匀性及周围正常组织保护上显著优于7F-IMRT计划,在充分保证靶区剂量的同时又不增加患者放疗毒副反应;但其机器输出量高于7F-IMRT计划,对射束的利用率不高。在后续治疗实施过程中,HT系统作为影像引导放射治疗技术,确保每次治疗过程中的精准度,值得临床应用。
Objective To compare the dosimetric differences of target areas and organs-at-risk between helical tomotherapy(HT)and 7-field intensity-modulated radiotherapy(7F-IMRT)for cervical cancer.Methods Twenty-five patients with cervical cancer who underwent helical tomography between March 2015 and October 2017 were enrolled in this study.All enrolled patients were treated in prone position,with a full bladder.Both HT planning and 7F-IMRT planning were carried out for each patient.The dosimetry parameters of target areas and organs-at-risk,and monitor units(MU)were compared between two planning modes.Results HT plan was better than 7F-IMRT plan in conformity index and homogeneity index[0.898±0.017 vs 0.834±0.013,P<0.001;0.062±0.012 vs 0.109±0.019,P<0.001].The D_(1 )and D_(2 )of planning target volume in HT group were lower than those in 7F-IMRT group(all P<0.001),while D_(mean),D_(98)and D_(95)in HT group were higher than those in 7F-IMRT group(P=0.048,P<0.001,P=0.015).The D_(max),D_(mean),V_(30)and V_(40)of small intestine,colon,rectum and bladder and the V_(50)of rectum were significant lower(P<0.001,P<0.001,P<0.001,P=0.001,P=0.006),and the V_(50)of the other organs-at-risk was slightly lower(P=0.130)in HT group as compared with 7F-IMRT group.Moreover,the V_(25),D_5,D_(mean)and D_(max)of femoral heads in HT group were significantly lower than those in 7F-IMRT group(all P<0.001).However,compared with 7F-IMRT group,HT group had a much higher MU.Conclusion HT plan which ensures the target dose without increasing the radiotherapy toxicity is superior to 7F-IMRT plan in conformity index,homogeneity index andorgans-at-risk sparing.However,the MU of HT plan is higher than that of 7F-IMRT plan,which indicates a lower utilization rate of beams in HT plan.As an image-guided radiotherapy technology,HT system is worthy of application for it can ensure the accuracy of each radiotherapy.
引文
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