PET-CT同机融合精度验证及在放疗靶区勾画中的应用

Accuracy verification of PET-CT image fusion and its utilization in target delineation of radiotherapy

目的 验证PET- CT同机融合的精度并实际应用于患者,为放疗的PET- CT定位及靶区勾画提供临床依据。方法 用不同浓度的18FDG灌注体模上的标志点和不同尺寸的圆柱体,PET和CT以层厚4mm扫描后的影像传输至eNTEGRA工作站和放疗计划系统(TPS)工作站,进行图像融合和三维重建,在PET和CT影像上测量标志点之间的距离和PET CT的融合误差。用扣除一定比例像素值的方法测量圆柱体的PET影像体积和CT影像体积,并把两者进行比较,同样的方法应用于10例非小细胞肺癌患者的10个肿瘤体积测量。结果 eNTEGRA和TPS工作站有良好的长度线性,但后者的图像融合误差明显大于前者。不同体积肿瘤、不同浓度18FDG需采用不同的像素值扣除比例。圆柱体和10个肿瘤PET影像体积和CT影像体积有较好的一致性。结论 PET -CT同机融合的精度完全符合放疗的临床要求,扣除一定比例像素值的方法可用于PET影像的肿瘤范围的勾画。

Objective Evaluate the accuracy o f co-registration of PET and C T (PET-CT) images on line with phantom, and utilize it on patients to provide c l inical evidence for target delineation in radiotherapy. Methods A phantom with m arkers and different volume cylinders was infused with various concentrations of 18FDG, and scanned at 4?mm by PET and CT respectively. Aft er having been transmi tted into GE eNTEGRA and treatment planning system (TPS) workstations, the image s were fused and reconstructed. The distance between the markers and the errors were monitored in PET and CT images respectively. The volume of cylinder in PET and CT images were measured and compared by certain pixel value proportion deduc tion method. The same procedure was performed on the pulmonary tumor image in te n patients. Results eNTEGRA and TPS workstations had a good length linearity, b ut the fusion error of the latter was markedly greater than the former. Tumors i n different volume filled by varying concentrations of 18FDG required different pixel deduction proportion. The cylinder volume of PET and CT images were almost the same, so were the images of pulmonary tumor of ten patients. Conclusions T he accuracy of image co-registration of PET-CT on line may fulfill the clinica l demand. Pixel value proportion deduction method can be used for target delineati on on PET image.