A preliminary study on target motion in esophageal cancer during normal breathing with four-dimensional computed tomography / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the characteristics of target motion in esophageal cancer during normal breathing with four-dimensional computed tomography(4DCT). Methods Twenty patients with primary esophageal cancer received respiratory gated 4DCT to obtain the target motion during normal breathing and delineate the gross tumor volume (GTV). The center coordinate and volume of each GTV were measured and recorded to calculate the displacement of the GTV center and the change in volume in different respiratory phases. Results The displacement of the GTV center in each esophageal segment in superior-inferior direction (0.521±0.319 cm) was significantly greater than that in right-left direction (0.169± 0.083 cm) and that in anterior-posterior direction (0.167±0.095 cm)(all P<0.05). The maximum displacement of the GTV center in each direction was significantly different in different esophageal segments(all P<0.05).The displacement of the GTV center in each direction was not entirely consistent in different respiratory phases. The displacement of the GTV center in each direction in T50phase was greatest when T0phase was the reference phase. The volume of GTV had no significant changes at the end of the expiratory phase and the inspiratory phase (P=0.313). Conclusions The displacement of GTV center in each esophageal segment in superior-inferior direction is significantly greater than that in right-left direction and that in anterior-posterior direction and the displacement of GTV center in each direction is significantly different in different esophageal segments. Therefore, all the factors should be considered to develop a reasonable target for precise radiotherapy. For esophageal cancer in cervical and upper chest esophageal segment,it is reasonable to delineate ITV based on the fusion image of the images at the end of inspiratory phase and expiratory phase. The deformation of target volume of the esophageal cancer in the cervical and upper chest esophageal segment is not significant in the respiratory cycle.