摘要目的 探讨模拟退火逆向优化算法(IPSA)在以插植针为施源器的宫颈癌三维后装腔内放疗中的应用效果.方法 以2016年10月至2018年7月接受根治性外照射及腔内联合组织间插植的局部晚期宫颈癌患者60例为研究对象,其中宫腔管联合1～4根插植针的患者各15例.在每例患者的同一套CT图像上,分别用正向的图形优化(GRO)方式和IPSA完成两种放疗计划,采用配对t检验分析两种计划方式的剂量学差异.结果 IPSA计划的D90、V100均高于GRO计划(t=-4.742、-4.823,P＜0.05),但靶区一致性指数(CI)和靶区适形指数(COIN)略低于GRO计划(t=9.642、8.783,P＜0.05).两组计划的靶区高量(V150、V200、V300)比较,差异无统计学意义(P＞0.05).两组计划的膀胱、直肠D2cm3相近(P＞0.05).宫腔管联合1根插植针时,IPSA较GRO的平均D90只提高了4 cGy(P＞0.05);但随着插植针管数的增加,IPSA相比于GRO,D90提高的幅度也逐渐增加;当增加到4根插植针时,IPSA较GRO的平均D90增加了14 cGy(t=-3.180,P＜0.05).与GRO相比,IPSA的V100提高的幅度同样随着插植针管数的增加而逐渐增加.结论 在以宫腔管联合插植针为施源器的宫颈癌三维后装治疗中,相比于GRO计划,IPSA计划在未增加靶区高量和危及器官剂量的情况下,可以提高靶区的覆盖度(D90、V100),且随着插植针管数的增多,IPSA较GRO在提高靶区覆盖度方面的优势也更为明显.

abstractsObjective To evaluate the effect of an inverse planning simulated annealing (IPSA) in the treatment of cervical cancer with combined intracavitary and interstitial three-dimensional brachytherapy.Methods A total of 60 patients with locally advanced cervical cancer who received both external beam radiotherapy and combined intracavitary and interstitial brachytherapy in our hospital from October 2016 to July 2018 were enrolled.Patients were divided into four groups with 15 patients each according to the number of needles applied (1,2,3,and 4 needles,respectively).Dosimetric distributions were optimized with both Graphical optimization (GRO) and IPSA.Paired t-test was applied to compare the dosimetric differences between plans optimized with GRO and IPSA.Results The Dg0 and V100 of IPSA plans were higher than those of GRO (t=-4.742,-4.823,P＜0.05),while the conformity index (CI) and conformal index (COIN) were slightly lower than those of GRO plans (t=9.642,8.783,P＜0.05).No significant difference in the V150,V200,V300 between IPSA and GRO (P＞0.05) was observed.There was also no significant difference in the D2cm3 of bladder and rectum between IPSA and GRO (P＞0.05).The difference of Dg0 between IPSA and GRO was increased as the number of implanted needles increased,which increased from 4 cGy to 14 cGy as the number of needle increased from 1 to 4.The difference of V100 between GRO and IPSA was also increased as the number of needle increased.Conclusions In the treatment of cervical cancer with combined intracavitary and interstitial threedimensional brachytherapy,IPSA plan could improve the target coverage(D90,V100)without increasing the dose to the OARs and high dose region in the target compared with GRO.With the numbers of needles increased,the advantage of IPSA increased in terms of target coverage.