^(18)F-FDG-PET-CT模拟定位在Ⅲ期非小细胞肺癌放疗中的应用研究

A Study on the Application of 18F-FDG-PET-CT for the Radiotherapy of Patients with Stage Ⅲ Non-small Cell Lung Cancer

背景与目的PET-CT通过功能影像与解剖影像的结合,有利于更加准确地勾画非小细胞肺癌(non-small cell lung cancer,NSCLC)放射治疗靶区,PET-CT定位可能成为放疗模拟定位的新平台,而提高精确放疗的疗效。本研究试图探讨18F-FDG-PET-CT对CT难以界定的NSCLC放疗计划的影响。方法对诊断明确的30例Ⅲ期NSCLC患者进行治疗体位的PET-CT扫描,扫描数据传入GE Advantage Sim6.0放疗工作站,放疗科医生与CT和核医学科医生分别根据CT、PET-CT融合图像进行临床分期与靶区勾画,并制定相应的放疗计划。选择大体肿瘤体积(gross tumor volume,GTV)、计划靶体积(planning tumor volume,PTV)、周围正常组织受量等指标进行统计学分析。结果①PET-CT改变临床分期:10%(3/30)的病例分期升高,10%(3/30)的病例分期降低;②PET-CT改变GTV和PTV:60%(18/30)的病例靶体积缩小,40%(12/30)的病例靶体积增大,其中体积发生明显变化者(变化>25%)占56.67%(17/30),但全组GTV、PTV变化不明显(P>0.05);③PET-CT改变治疗计划参数:给予相同的靶区剂量60Gy/30次,PET参与后PTV变化者的周围正常组织受量均发生相应的变化,但各项指标全组变化不明显(P>0.05)。结论应用PET-CT模拟定位并勾画靶区,可避免靶区扩大或遗漏,对提高CT难以界定的Ⅲ期NSCLC靶区精确性有重要意义。

Background and objective PET-CT have emerged as powerful imaging tools in radiotherapy to add information that might lead to a change in GTV definition in patients with non-small cell lung cancer （NSCLC）. The aim of this study was to investigate the impact of co-registering 18F-FDG-PET-CT images on the gross tumor volume （GTV）, the planning target volume （PTV）, and critical organ dose in radiation therapy planning of NSCLC. Methods Thirty patients with stage Ⅲ NSCLC, referred for radical radiation therapy, underwent PET-CT scanning. GTV was delineated on the CT imaging and PET-CT fused imaging respectively. The two images were used to develop the radiotherapy planning at the GE Advantage Sim 6.0 workstation. Dose-volume histograms （DVH） parameters were selected to be paralleled to compare the quality of the two plans and the impact of PET-CT on radiation plan （RP） was further analyzed. Results （1） PET-CT image changed the clinical stage： 3 patients （10%） upstaged and 3 patients （10%） downstaged. （2） PET-CT image altered GTV and PTV： GTV and PTV was decreased by PET-CT image fusion in 18 patients （60%） and was increased in 12 patients （40%）. A significant （25%） treatment volume modification was observed in 17 patients （56.67%）. （3） PET-CT image changed the parameters of DVH： to deliver the same target dose of 60 Gy in 30 fractions, all dose-volume characteristics decreased in treatment planning for the 18 patients with decreased PTV based on PET-CT; the issue was the contrary for the 12 patients who had enlarged PTV based on PET-CT. Conclusion The use of the co-registration of PET-CT significantly reduced inaccurate outlining of the GTV and/or to geographic misses.