PET/CT融合图像对Ⅲ期非小细胞肺癌精确放疗靶区和计划的影响

Impact of positron emission tomography/computed tomography coregistered images on target volume delineation and precises radiotherapy planning with stage Ⅲ non-small cell lung cancer

目的探讨18氟-脱氧葡萄糖(18F-FDG)PET/CT对Ⅲ期非小细胞肺癌(NSCLC)精确放疗中肿瘤靶区勾画以及正常肺组织照射剂量分布的影响。方法行18F-FDGPET/CT胸部精确放疗定位的32例Ⅲ期NSCLC患者入组。使用PhilipsPinnacle3治疗计划系统,由三位放射肿瘤医师和一位物理师分别先后依据CT图像、PET/CT融合图像勾画肿瘤大体靶区(GTV),分别表示为GTVCT和GTVPET/CT。随机选取一位医师勾画的GTV,按相同参数外放形成计划靶区(PTV)并制订精确放疗计划,分别表示为TrialCT和TrialPET/CT。分析PET/CT融合图像对肿瘤靶区勾画以及对正常肺组织照射剂量分布的影响。结果 (1)PET/CT改变了GTV的大小,基于PET/CT图像勾画的GTV小于CT图像勾画的GTV,两者之间差异有统计学意义(P=0.008),并且不同勾画者应用PET/CT图像勾画的肿瘤靶体积变异减小(7.05cm3vs.22.00cm3)。(2)肺不张组TrialPET/CT肺组织剂量体积直方图(DVH)参数(V5～V50,MLD)降低,与TrialCT相比差异有统计学意义(P<0.01或P<0.05);无肺不张组肺组织DVH参数在TrialPET/CT和TrialCT之间差异无统计学意义(P值为0.16～1.00)。结论 18F-FDGPET/CT可提高Ⅲ期NSCLC肿瘤靶区勾画的准确性和精确性。对于伴有肺不张的Ⅲ期NSCLC患者,PET/CT制订的精确放疗计划能够降低正常肺组织的照射剂量。

Objective To investigate the impact of 18F-fluorodeoxyglucose（18F-FDG）PET/CT on target volume delineation and dose distributions to normal lung tissue for patients with stage Ⅲ non-small cell lung cancer（NSCLC）.Methods 18F-FDG PET/CT scanning for thoracic localization was performed in 32 NSCLC patients with stage Ⅲ.PET/CT coregistered images imported to Philips Pinnacle3 planning system for target volume delineation.Three radiation oncologists and one radiation physician delineated gross target volume（GTV）by visualization independently,first using CT image alone and then PET/CT coregistered images,marked with GTVCT and GTVPET/CT,respectively.Selected one set of GTV randomly,expanded with identical margins to create planning target volume（PTV）,precise radiotherapy plans were established,marked with TrialCT and TrialPET/CT,respectively.The impact of PET/CT on target volume delineation and dose distributions to normal lung tissue was analyzed.Results（1）There was a significant change of GTV delineated between CT and PET/CT image modalities,GTV defined by PET/CT was smaller than CT,there was statistically significant difference between them（P=0.008）,and the variability of target volume defined by PET/CT was smaller than CT（7.05 cm3 vs.22.00 cm3）.（2）Normal lung tissue dose-volume histogram（DVH）parameters（V5-V50,MLD）of group ＇atelectasis＇ in TrialPET/CT decreased comparing with TrialCT,there was statistically significant difference between them（P0.01 or P0.05）;whereas,these DVH parameters between TrialPET/CT and TrialCT of group ＇non-atelectasis＇ were not（P value ranged from 0.16 to 1.00）.Conclusions 18F-FDG PET/CT coregistered images improved the overall accuracy and precision of GTV delineation in stage Ⅲ NSCLC patients,and decreased dose distributions to normal lung tissue of NSCLC patients with atelectasis.