Application of PET/CT combined with 4DCT in radiotherapy of esophageal carcinoma / 重庆医学

ABSTRACT

Objective To study the correlation of positron emission tomography/computed tomography (PET/CT) under different standardized uptake value (SUV) thresholds and full time four-dimensional computed tomography (4DCT) in esophageal carcinoma target delineation and explore the optimum SUV value that can accurately reflect the spatial movement of the target.Methods Eighty-two patients with esophageal cancer initial treatment in this hospital were respectively performed the scanning localization by PET/CT and 4DCT on the same day.Then different SUV thresholds (≥2.0,2.5,3.0,3.5) and the percentage of maximum SUV value (≥20％ SUV 30％ SUV 40％ SUVmax) were selected to delineate the internal gross target volume (IGTV) PET/CT in PET/CT,the ten phases of the 4DCT were collected to obtain the full time target IGTV10,the target center offset,volume ratio and conformity index (CI) were compared between the two images,the relatively good SUV value with the registration in 4DCT target was picked out,then the correlation between the target center offset,volume ratio and CI with the IGTV10 volume,long axial diameter of IGTV10,displacement of head-to-foot direction and spatial motion was analyzed.Results When the SUV threshold was 2.0 or 20 ％ SUV the spatial matching degree of 4DCT and PET/CT images was better.The head-to-foot direction displacement and special motion displacement in the target center offset of IGTVPET2.0,IGTVPET20％ and IGTV10 showed the positive correlation (P＜0.05);the volume ratio had no correlation with the IGTV10 volume,IGTV10 long axial diameter,head-to-foot direction displacement and special motion displacement (P＞0.05);CI had positive correlation with IGTV10 volume and IGTV10 long axial diameter,while had negative correlation with the head-to-foot direction displacement and special motion displacement (P＜0.05).Conclusion When SUV taking 2.0 or 20％ SUV the esophageal carcinoma target volume of PET/CT is similar to that of full time 4DCT,but there are still some deviations in the conformity index,therefore the PET/CT threshold value and 4DCT time phase selection should be further studied.