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.
ABSTRACT
Objective To investigate the motion characteristics of primary thoracic esophageal carcinoma with four-dimensional computed tomography(4DCT).Methods Sixteen patients with primary thoracic esophageal carcinoma received respiratory gated 4DCT imaging,mapping the GTV1-GTV10 on every patient's each subsequent CT image of 10 images in the full-respiratory phase,and measuring the displacement of each centre of GTV.These displacements and directions were analyzed on different segments of esophagus.Results The mean total lung volume and GTV volume was 2993.5 cm3,35.00 cm3 and 3362.12 cm3,34.84 cm'respectively on end-expiration and end-inspiration phases(t=12.36,P=0.000and t=-0.61,P=0.546).The total mean peak to peak displacement of GTV were 0.65 mm,0.55 mm,and 2.03 nnn in x,y-and z-axis direction,respectively(F=41.14,P=0.000).The motion in x-axis,y-axis and z-axis were 0.50 mm,0.48mm,1.23 mm in the upper segment(F=5.45,P=0.017),0.68 mm,0.62 mm,1.97 mm in the middle segment(F=27.74,P=0.000),0.72 mm,0.38 mm,3.05 mm in the lower segment,respectively(F=15.61,P=0.000).Conclusions The displacement of tumor in z axis is more notable than x-,y-axis in thoracic esophageal carcinoma.The displacement of tumor x-,y-and z-axis is different in different segment of thoracic esophageal carcinoma.