图像引导对宫颈癌治疗的作用

目的 分析宫颈癌根治性图像引导放疗(IGRT)对靶区剂量的影响,探讨其合理应用模式。方法 选取2012—2016年于中国人民解放军总医院第七医学中心行螺旋断层放疗(HT)的20例宫颈癌患者,应用兆伏级CT(MVCT)图像在HT自适应模块上进行重建及模拟,分别得到有/无图像引导下的受照剂量参数;将各单次剂量分布和对应的融合CT图像传输至形变软件中进行剂量叠加得到总剂量参数。结果 无图像引导的模拟计划(Plan 2)的CTV、GTV和子宫体各方向位移均大于图像引导下的计划(Plan 1),以腹背方向和宫体位置变化最大;CTV、宫体V45Gy、V50Gy、D98%、Dmean和GTV的V50Gy均低于Plan 1(P<0.05);Plan 1左右位移与CTV和宫体D2%、D98%呈负相关(P<0.05),头脚位移与GTV的V45Gy、V50Gy呈负相关(P<0.05),腹背位移与宫体D98%呈负相关(P<0.05);Plan 2左右位移与CTV的D2%和宫体V50Gy呈负相关(P<0.05),头脚位移与CTV的D98%和宫体D98%、Dmean、V45Gy、V50Gy呈负相关(P<0.05),腹背位移与CTV的D98%和宫体D98%、Dmean、V45Gy、V50Gy及GTV的Dmean、V45Gy呈负相关(P<0.05)。结论 宫颈癌调强放疗中宫体位移较大且CTV低量区主要位于宫体,IGRT可明显降低位置偏差带来的剂量学差异。

The impact of image-guided radiation therapy on treatment of cervical cancer

Objective To evaluate the effect of radical image-guided radiotherapy (IGRT) on the target dose in cervical cancer and investigate the appropriate application mode. Methods Twenty patients with cervical cancer treated with helical tomotherapy (HT) in Seventh Medical Center of PLA General Hospital from 2012 to 2016 were selected. A megavoltage CT (MVCT) scan was performed before each treatment. The obtained MVCT images were used for dose parameter in the adaptive module of HT to obtain the actual dose (Plan 1) and the non-image-guided dose parameter was simulated (Plan 2). Each single dose distribution and the corresponding fused CT images were transferred to the software Mimvista 6.5 to obtain the total radiation dose parameter by dose superposition. Results The motion of CTV,uterus and GTV in Plan 2 was significantly larger than that of Plan 1(all P<0.05), and the largest changes were seen in the ventrodorsal and uterine direction. The V45Gy, V50Gy, D98% and Dmean of CTV and uterus and V50Gy of GTV in Plan 2 were significantly decreased compared with those in Plan 1(all P<0.05). The left-right motion of Plan 1 was negatively correlated with D2% and D98% of CTV and uterus (both P<0.05). The head-foot motion was negatively associated with V45Gy and V50Gy of GTV (both P<0.05). The ventrodorsal motion was negatively correlated with D98% of uterus (P<0.05). The left-right motion of Plan 2 was negatively correlated with D2% of CTV and V50Gy of uterus (both P<0.05). The head-foot motion was negatively associated with D98% of CTV, and D98%, Dmean, V45Gy and V50Gy of uterus (all P<0.05). The ventrodorsal motion was negatively correlated with D98% of CTV,D98%, Dmean, V45Gy and V50Gy of uterus, and Dmean and V45Gy of GTV (all P<0.05). Conclusions In intensity-modulated radiotherapy for cervical cancer, the uterine body displacement is large and the low CTV area is mainly located in the uterine body. IGRT can significantly reduce the dosimetric deviation induced by organ movement.