Fig. 1

Schematic diagram of esophageal carcinoma range and measurement of a deep ulcer. A Schematic diagram demonstrated that the esophageal lumen was evenly divided into four parts. The tumor (red) range was diagnosed as 0–1/4 (two blue arrow), 1/4–1/2 (yellow arc), 1/2–3/4 (green arc) and 3/4–1 (grey arc). B Schematic diagram demonstrated how ulcer depth (U, black), residual esophageal wall in the ulcer layer (R, red) and the the thickness of the lesion adjacent to ulcer (A, yellow) were measured