CT增强剂对食管癌三维适形放疗剂量分布的影响

目的探讨CT增强剂对食管癌靶区及各危及器官剂量分布的影响。方法选择食管癌患者10例,分别采集CT平扫和CT增强扫描的断层图像,然后将图像传入计划系统。分别在增强CT上勾画靶区、危及器官和设计三维适形放疗计划,并将勾画轮廓及计划复制到CT平扫上重新计算。对2套计划得出的剂量分布进行对比分析。结果靶区在D2%、D50%、D95%、D98%、Body95%、CI和HI方面的差异无统计学意义。危及器官肺V5、V20及Dmean;心脏V40及Dmean;脊髓最大剂量两者之间无统计学差异。Body、PTV、肺、心脏的CT值和电子密度在增强时高,差异有统计学意义。结论静脉注射造影剂对食管癌三维适形放疗剂量分布的影响很小,临床上可以接受这样的误差。

Effects of CT Strengthening Agent on Dose Distribution of Three-dimensional Conformal Radiotherapy in Esophageal Cancer

Objective To explore effects of CT strengthening agent on dose distribution of target area of esophageal and endangered organs.Methods 10 patients with esophageal cancer were selected,and plain CT and CT enhanced scan images were collected respectively into the planning system.The target region and organs at risk were sketched out on enhanced CT and three-dimensional conformal radiotherapy plan was designed,and then the sketched profiles and the plan were copied to plain CT to be recalculated.The dose distributions of the two sets of plans were compared and analyzed.Results The differences of D2%,D50%,D95%,D98%,Body 95%,CI and HI in the target area were not statistically significant.For the organs at risk,V5,V20,and Dmean of lung;V40 and Dmean of heart;maximal dose of spinal cord showed no significant difference between the two methods.Body,PTV,CT and electron density of lung and heart of enhanced CT were statistically higher than that of plain scan.Conclusion The influence of intravenous injection of contrast agents on dose distribution of three-dimensional conformal radiotherapy in esophageal cancer is very small,and such error is clinically acceptable.