Overview of the tumor delineation for one patient with middle thoracic esophageal cancer. (A) Gross tumor lengths delineated on CT images by different methods. (B) Gross tumor lengths delineated on FLT PET/CT images by different methods. Volumes are displayed in transaxial, sagittal and coronal planes. Purple, orange, blue and Red contours illustrate different parameters (e.g. GRAD, 1.4 SUV threshold, 30% of SUVmax and CT).