口服造影剂对胰腺癌容积旋转调强放疗剂量分布的影响  

Influence of oral contrast medium on dose calculation of volumetric modulated radiotherapy for pancreatic cancer

作　　者：牛静[1] 谭丽娜[1] 孙晓欢[1] 肖锋[1] 

机构地区：[1]第四军医大学西京医院放射治疗科,陕西西安710032

出　　处：《中华肿瘤防治杂志》2015年第8期629-632,共4页Chinese Journal of Cancer Prevention and Treatment

摘　　要：目的研究口服造影剂对胰腺癌容积旋转调强(volumetric-modulated arc therapy,VMAT)放疗剂量分布的影响。方法选取2013-04-01-2013-08-30第四军医大学西京医院放射治疗科6例胰腺癌放疗患者进行非增强CT扫描定位并设计VMAT计划,并在该套CT图像上分别赋予胃和十二指肠等造影剂区域不同CT值,将VMAT计划分别移植到改变了CT值的图像上,保持所有参数不变,重新计算剂量,利用剂量体积直方图和剂量分布图分别比较危及器官和靶区的剂量分布差异。结果随着CT值的增加,靶区适形度和均匀度均有变差趋势,靶区Dmin、Dmax和V95呈下降趋势。当CT值≥800HU时,靶区已不符合临床要求,多层CT横断面上95%的处方剂量已不能包绕靶区。危及器官的剂量分布差异有统计学意义(P<0.05),但各项参数均在临床正常范围内,可忽略不计。结论口服造影剂浓度的变化对胰腺癌容积旋转调强的剂量分布有一定影响,为了提高靶区和危及器官勾画的准确率,放疗定位时可适当口服造影剂,但应掌握好剂量和扫描时间。当CT值<800 HU时,造影剂并不会对靶区和危及器官的剂量分布造成太大影响。当CT值≥800HU时,造影剂会对靶区和危及器官的剂量分布造成影响,定位时应尽量避免。OBJECTIVE To evaluate the effect of an oral contrast medium on dose calculations in volumetric-modu- lated radiation therapy （VMAT） of pancreatic cancer. METHODS A total of 6 oral-contrasted patients with pancreatic cancer were given one set of CT in the position without oral contrast medium and VMAT was designed. The Hounsfield u- nit （HU） values of the stomach and duodenum were overridden to model the different contrast-enhanced scenarios and the plans were copied to enhanced CT to be recalculated. The radiation doses calculated from the sets of CT were compared with regard to planning volumes（PTV） and the organs-at- risk（OARs）. RESULTS The doses （Drain , Dmax and V95 ） of PTV calculated from different scenarios were decreased with the increase of HU value, but CI and HI in the target area had statistically negative influence. When the HU value of enhanced area exceeded 800 the average variation could not meet clinical tolerable,PTV volume could not receive 95% of the prescribed dose on some CT scans. There was no statistically significant difference for OARs（P〈0.05）, but all parameters met the clinical requirements that can be ignored. CONCLU- SIONS The oral contrast medium has significant effect on the dosage of VMAT of pancreatic cancer. In order to improve the accuracy of PTV and OARs,oral contrast medium should be taken carefully for optical dosage at the right time. When the HU value of enhanced area exceeded 800 the average variation could not meet clinical tolerable, It should be taken into account in radiotherapy.

关 键 词：胰腺癌 容积旋转调强 口服造影剂 剂量分布 

分 类 号：R735.9[医药卫生—肿瘤]