PET-CT在局部晚期非小细胞肺癌调强放疗中的应用

The clinical application of PET-CT for the intensive modulated radiotherapy of patients with local advanced non-small cell lung cancer

目的探讨PET-CT对局部晚期非小细胞肺癌(NSCLC)临床分期的诊断及其融合图像下勾画靶区对调强放疗计划的影响。方法对13例局部晚期NSCLC患者同一体位分别进行增强CT和PET同机扫描,图像重建后传输至三维治疗计划系统(3D-TPS)进行自动图像融合。PET-CT下诊断患者的分期;分别在CT、PET-CT融合图像上勾画靶区,设计放疗计划。患者均采用5野调强放疗,常规处方剂量60Gy/30f。比较两个计划的V20、全肺平均受量(MLD)、心脏平均受量、脊髓最大受量。结果 5例患者分期改变:3例升高,2例下降;CT下勾画靶区GTV、PTV分别为(159.35±84.44)cm3、(442.12±172.57)cm3,显著高于PET-CT下勾画的GTV和PTV[(148.22±75.08)cm3、(428.64±157.91)cm3];PET-CT下计划的全肺V20、MLD、心脏平均受量、脊髓最大受量等各项剂量学参数均优于CT下的计划(P<0.05)。结论 PET-CT较CT更有利于局部晚期NSCLC放疗靶区的勾画,可以更好地保护周围正常组织和器官。

Objective To investigate the impact of PET-CT on the clinical staging and target volume delineation of fused positron emission tomography（PET） and computed tomography（CT） images on the intensive modulated radiotherapy（IMRT） planning for the patients with local advanced non-small cell lung cancer（NSCLC）.Methods Thirteen patients with local advanced NSCLC were referred for IMRT.Each patient was underwent CT and PET scan for simulation plan in the same treatment position.PET images were co-registered CT images.The clinical staging of all patients was determined by PET-CT.Target volume 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 by the same doctor.Two kinds of treatment plans were designed based on GTVcT and GTVPET-CT by the same physicist.The plan for each case was finished with 5 fields IMRT and given with a total dose of 60Gy at 2Gy per fraction.The following DVH parameters were evaluated.The indexes including V20,mean lung dose,mean dose to heart and the maximum dose to spinal cord were evaluated too.Results The clinical stages of five patients were changed by PET-CT image including 3 up-staged and 2 down-staged.Therefore,the management decision was modified in 1 patient.PET-CT image altered GTV and PTV：the mean GTV,PTV delineated on CT and PETCT were 159.35-± 84.44cm3,442.12 ± 172.57cm3 and 148.22 ± 75.08cm3,428.64 ± 157.91cm3 respectively.PET-CT image changed the parameters of DVH：the difference of indexes including V 20,mean lung dose,mean dose to heart and the maximum dose to spinal cord between the two IMRT plannings were statistically significant.The plan based on the GTVPET-CT was proved to be better than it based on the GTVcT according to the DVH parameters.Conclusion PET±CT image fusion appeares to not only make the outlining of GTV accurate,but also have an advantage on dose-reduction of organ at risk in treatment planning for the patients with local advanced NSCLC.