The Impact of Contrast Enhanced CT Scanning on Countering of GTV and the Construction of IGTV for Primary Thoracic Esophageal Cancer Based on 4D-CT

Abstract

To investigate the difference of the GTV volume on each phase between enhanced four dimensional computed tomography (4D-CT) scanning (C+) and conventional 4D-CT scanning (C-), and the influence to the construction of IGTV for primary thoracic esophageal cancer. 40 patients with primary thoracic esophageal cancer, 12 in the upper, 17 in the middle, 11 in the lower, were completed conventional 4D-CT scanning and enhanced 4D-CT scanning sequentially under free breathing. The GTVs were drawn by a single physician with same standard under the same window level and the same window width on the conventional 4D-CT images, the IGTV was constructed based on each 4D-CT data set respectively. The same work would have been done on the enhanced 4D-CT images one month later. The coefficient of variation (CV) on the C+ images were smaller than those on the C- images, but the differences on the volumes of GTV and IGTV, the length of the GTV on the Z axes were not significant between C+ images and C- images for the upper and lower tumors (P>0.05); However, for the middle tumors, the volumes of GTV and IGTV, the length of the GTV on the Z axes on the C+ images were smaller than those on the C- images (P<0.05). Enhanced 4D-CT scanning can reduce the error of target outlining and can construct accurate IGTV for the middle thoracic esophageal cancer, but no benefits for the upper and lower tumors.