局部进展期宫颈癌四野盒式照射联合ICBT融合剂量学研究

摘要

目的:分析局部进展期宫颈癌(locally advanced cervical cancer,LACC)四野盒式照射联合腔内近距离放疗(intracavitary brachytherapy,ICBT)靶区和危及器官(organs at risk,OARs)融合剂量学分布.方法:20例LACC患者,行MRI和模拟CT扫描,融合MRI/CT图像,勾画靶区和OARs.设置四野/ICBT计划,单独计算靶区和OARs剂量,相加为几何剂量;叠加四野与ICBT形成融合计划,计算靶区和OARs融合剂量.计算ICBT对靶区和OARs剂量贡献.结果:几何计算导致低估靶区剂量和高估OARs剂量.除GTV外,ICBT对CTV和PTV也有贡献.膀胱充盈及空虚比较,靶区几何剂量低于融合剂量(P<0.05),OARs几何剂量高于融合剂量(P<0.05).膀胱充盈有利于降低OARs剂量.结论:LACC四野联合ICBT放疗融合剂量学评估可能优于几何评估,但有待进一步临床观察.膀胱保持一定容量有利于降低OARs剂量.%Objective:To analyze fusion dose distribution of targets and organs at risk(OARs)for locally advanced cervical cancer(LACC)with BOX irradiation combining intracavitary brachytherapy(ICBT).Methods:Total 20 patients with LACC were undergone MRI and simulation computed tomography(Sim-CT)scan respectively,and fused MRI/Sim-CT,delineated targets and OARs.Designed BOX/ICBT radiation plan in TPS,radiation source as 6MV-x-ray and 192Ir respectively.Separately alone calculated BOX/ICBT doses of targets and OARs,and adding up as geometric dose.Used TPS plan superposition function,superimposed BOX/ICBT plans as an integration plan and calculated fusion doses of targets and OARs.Calculated the geometric and fusion dose contribution rates for targets and OARs from ICBT.Results:Geometric calculation of irradiation dose for targets and OARs woud result to underestimate targets dose and overstimate OARs dose under different bladder statues.The dose contribution of GTV was main contribution from ICBT,but for CTV and PTV also contribute.Compared filling and empty bladder,geometric doses of targets were lower than the fusion doses(P<0.05),geometric doses of OARs were higher than the fusion dose(P<0.05).Filling bladder was beneficial to reduce exposed dose of OARs.Conclusion:Fusion dosimetric assessments may be superior to geometric dosimetric assessments for LACC with BOX irradiation combining ICBT radiotherapy,but it would be further clinical observation.Bladder would maintain certain capacity,it would be beneficial to reduce exposed dose of OARs.