Abstract:

Objective To investigate the value of PET-CT image fusion to delineate the target of intensity modulated radiation therapy（IMRT） in locally advanced non-small cell lung cancer（NSCLC）， and the impact on target volume and dose of normal lung tissue. Methods Thirty NSCLC patients of clinical stage ⅢA and ⅢB were randomly selected. Target and organ at risk were delineated on the same fixed position according to enhanced CT images and fusion images of PET/CT and CT, respectively. Then the volume of gross tumor volume（GTV） and planning target volume（PTV） under these two status were compared. Moreover， the percent of the total lung volume exceeding 5 Gy（V5）， percent of the total lung volume exceeding 20 Gy（V20）， mean dose of lung irradiated（MLD） in two different conformal IMRT plans were observed when the dosage of PTV was up to 60 Gy/30 f. Results The GTV volume on fusion images of PET-CT/CT was （248.39±94.80）cm3, less than （311.22±99.16）cm3 on the enhanced CT images in 30 cases. The difference was statistically significant（P＜0.05）. PTV， extended from GTV， in fusion images of PET-CT/CT was （356.68±92.73）cm3, while in the enhanced CT images were （433.58±107.89 cm3） with significant difference（P＜0.01）. The V5， V20 and MLD of whole lung in the two plans were compared. In fusion images of PET-CT/CT program， V5， V20 and MLD was （51.26±10.50）％，（25.71±5.17）％ and （1595.27±148.24） cGy, remarkly less than （56.41±9.55）%, （29.09±4.10）% and （1693.59±100.60） cGy in the enhanced CT program with significant difference（P＜0.05）. Conclusion Application of PET-CT/CT fusion image to delineate the targets of IMRT can improve the accuracy of target delineation volume and reduce the dose of normal lung tissues.