1. Division of Gastroenterological Surgery, Chiba Cancer Center, Chiba 260‑8717, Japan
2. Graduate School of Engineering, Faculty of Engineering, Chiba University, Chiba 263‑8522, Japan
3. Department of Diagnostic Radiology and Radiation Oncology, Graduate School of Medicine, Chiba University, Chiba 260‑8670, Japan
4. Division of Hepato‑Biliary‑Pancreatic Surgery, Chiba Cancer Center, Chiba 260‑8717, Japan