Delineation of Recurrent abdominal Lymph Nodes on Template CT

We selected a 70-year-old woman with middle thoracic ESCC who underwent esophagectomy in the real world as a standard patient. This patient met the following criteria: (1) lymphadenectomy including stations 1–4, station 7, station 8 and station 9 were carried out; (2) no identified ALNR; (3) no obvious abnormalities in organs and structures in the abdominal region; and (4) performance of contrast-enhanced CT scanning of a 0.62/0.63 mm thick section from the cricoid cartilage to 5.00 cm below the iliac bifurcation. The template CT images were imported into the Pinnacle 3 treatment planning system (version 9.8.0.6007; Philips Medical Systems, Fitchburg, WI, USA) for the delineation and reconstruction of LNs.

All the locations of ALNR were transferred to the corresponding anatomic positions in the template CT images by two radiation oncologists and a radiologist. The anatomic positions were mainly referred to the surrounding vascular and skeletal structures. All LNs were plotted with a diameter of 2.00 mm according to their geometric centre. When there were mixed LNs, we plotted the geometric centre of each node that was distinguishable in its respective location. Otherwise, we plotted a geometric centre for the mixed lymph node. After the areas of ALNR of all the patients were transferred to the template CT images, the merged target volume was expanded outward by 3.00 mm and expanded 4.00 mm on the upper and lower bounds for all these plotted LNs.