PET-CT图像融合在食管癌精确放疗中的应用

目的探讨PET-CT融合图像勾画靶区的食管癌三维适形放疗计划的优势。方法对16例食管癌病例分别进行CT、PET同机扫描,图像重建后传输至三维治疗计划系统(3D-Treatment planning system,TPS),进行自动图像融合,由同一临床医师分别在CT、PET-CT融合图像上勾画出,同一物理师分别设计优化TPS计划,给予常规处方剂量2.0Gy×30次,每个计划采用5个方向照射野来实现较好的靶区剂量分布,并达到周围正常组织保护的目的。计算各计划的靶区体积并显示剂量体积直方图(dose-volume histogram,DVH),比较2个计划的全肺平均受量(mean lung dose,MLD)、双肺受照超过20Gy的体积占全肺体积的百分比(V20)、气管平均受量、心脏平均受量、脊髓最大受量。结果CT勾画的GTV体积均值为67.10cm3,大于PET-CT融合图像下勾划的GTV均值60.82cm3,包括MLD、全肺V20、气管平均受量、心脏平均受量、脊髓最大受量在内的各项DVH参数的比较显示,均以PET-CT勾画靶区的计划明显优于CT勾画靶区的计划。结论PET-CT图像融合基础上勾画靶区制定放疗计划,可更有效的保护周围正常组织和器官。

Application of CT and Positron Emission Tomography Image Fusion for Conformal Radiotherapy in Esophageal Carcinoma

Objective To study the advantage of fused positron emission tomography (PET) and computed tomography (CT) images on conformal radiotherapy planning for esophageal carcinoma patients. Methods Sixteen patients with esophageal carcinoma were referred for radiotherapy. Each patient underwent CT and PET scan for simulation plan in the same treatment position. PET images were coregistered with CT images. Target delineation was initially performed on CT images, and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume.Two kinds of treatment plans were designed based on GTVCT and GTVPET-CT. The following DVH parameters were evaluated: Mean lung dose, V20, mean dose to trachea and heart, and the maximum dose to spinal cord. Results The mean GTV delineated on CT and PET-CT were 67.10 cm3 and 60.82 cm3 respectively. Plan based on the GTVPET-CT are better than plan based on the GTVCT accoding to the DVH parameters.Conclusion In our study, CT and FDG-PET image fusion appeared to have an advantage on dose-reduction of organ at risk in treatment planning of esophageal carcinoma.