目的：比较CT图像和CT/MRI融合图像来源的肺癌脑转移肿瘤靶区，评价CT/MRI融合靶区容积应用于三维适形放射治疗时，对治疗剂量的影响。方法：将20例非小细胞肺癌脑转移患者的增强CT和MRI扫描的图像传送至图像处理工作站，在CT和CT/MRI融合图像上分别勾画GTV和周围重要的器官。每个病例分别在CT图像和CT/MRI融合图像都做1个三维适形放射治疗计划。肿瘤的处方剂量为60 Gy，比较2个治疗计划中肿瘤靶区的95%容积（D95）受照平均剂量、周围正常组织的5%容积（D5）受照平均剂量。结果：CT/MRI融合图像上的肿瘤靶区平均比CT上的肿瘤靶区大21.32％。用CT上勾画的靶区有一部分肿瘤处于低剂量区，CT/MRI融合图像上的靶区D95剂量分布较好，但在周围重要器官的剂量分布较高。结论：CT/MRI融合图像有助于靶区的确定，在三维适形放射治疗计划上的肿瘤靶区剂量分布足够，能提高靶区勾画的准确性，更利于精确放疗的实施。%Objective:To compare the CT images and CT/MRI images fusion sources of lung cancer with brain metastasis tumor target,and to evaluae the effects of dose for treatment on target volume CT/MRI fusion for three-dimensional conformal radiotherapy. Method:The enhancement CT and MRI scan image of 20 patients with brain metastases from non-small cell lung cancer was transfer to image processing workstation,GTV and surrounding vital organs on CT and CT/MRI images fusion was delineated respectively. A three-dimensional conformal radiotherapy plan was done in CT images and CT/MRI fusion images of ach case. Tumor prescription dose was 60 Gy. Compared the average dose of the 95%volume(D95)tumor target,the average dose of the 5%of the normal tissue around of the two treatment plans. Result:The tumor targets of the CT/MRI images fusion was greater than those of the CT tumor targets on average 21.32%. A part of the tumor was in the low dose region which was paint with CT target area delineated.The target D95 dose distribution was better on the CT/MRI images fusion,but which was higher in the surrounding vital organs.Conclusion:CT/MRI fusion image is helpful to determine the target area,which is enough in the three dimensional conformal radiotherapy plan on tumor target dose distribution,and can improve the accuracy of the target sketch,also more helpful to the implementation of precise radiotherapy.
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