螺旋断层放疗在早期年轻宫颈癌患者保卵巢根治术后放疗中的剂量学研究

A dosimetric study of helical tomotherapy in radiotherapy after ovarianconserving radical surgery for young patients with early-stage cervical cancer

目的:比较螺旋断层放疗(helical tomotherapy,TOMO)和调强放射治疗(intensity-modulated radiotherapy,IMRT)在早期年轻宫颈癌患者保卵巢根治术后放疗中的剂量学特点。方法:共纳入宫颈癌保卵巢根治术的早期年轻患者21例,同一患者均分别采用TOMO和IMRT两种照射技术设计放疗计划,比较2种计划靶区剂量的适形度(conformity index,CI)和均匀性(homogeneity index,HI),靶区和危及器官(organs at risk,OARs)的剂量学分布以及机器跳数(monitor unit,MU)、治疗时间(delivery time,DT)。结果:采用TOMO放疗技术的肿瘤靶区CI为0.894±0.006,HI为1.082±0.006,均优于IMRT(0.855±0.008,1.106±0.006)(P=0.000,P=0.023),差异有统计学意义。对于卵巢的保护,TOMO计划的V5仅有17.20±0.18,明显小于IMRT计划(38.92±0.70),差异有统计学意义(P=0.000);Dmean(4.21±0.03)也低于IMRT计划(4.82±0.04)。对于其他正常器官,TOMO同样具有剂量学优势,但是TOMO需要更多的治疗跳数(7 729±42),而IMRT的平均治疗跳数为(1 974±23),差异有统计学意义(P=0.000)。两者的治疗时间相当。结论:TOMO技术能获得更好的靶区适形度和均匀性,对于卵巢及盆腔正常器官的保护更优,是早期年轻宫颈癌患者保卵巢根治术后放疗的最好选择。

Objective:To investigate the dosimetric characteristics of helical tomotherapy(TOMO) versus intensity-modulated radiotherapy(IMRT) in radiotherapy after ovarian-conserving radical surgery for young patients with early-stage cervical cancer. Methods:A total of 21 young patients with early-stage cervical cancer were enrolled,and each of them received radiotherapy with both TOMO and IMRT. The two methods were compared in terms of conformity index(CI) and homogeneity index(HI) of target volume,dose distribution in target volume and organs at risk(OARs),number of monitor units(MUs),and delivery time(DT). Results:TOMO had sig-nificantly better CI and HI of the target volume than IMRT(CI:0.894±0.006 vs. 0.855±0.008,P=0.000;HI:1.082±0.006 vs. 1.106±0.006,P=0.023). As for ovarian protection,TOMO had significantly lower V5 and Dmean than IMRT(V5:17.20±0.18 vs. 38.92±0.70,P=0.000;Dmean:4.21±0.03 vs. 4.82±0.04). TOMO also had dosimetric advantages for the normal tissues,but TOMO needed a significantly higher number of MUs than IMRT(7729±42 vs. 1974±23,P=0.000). These two methods had a similar DT. Conclusion:Compared with IMRT,TOMO can obtain better conformity and homogeneity of target volume and better protect the ovary and the pelvic cavity,and therefore,it is the best choice for radiotherapy after ovarian-conserving radical surgery for young patients with early-stage cervical cancer.