Fig. 1. The G-Master. (A) G-Master body. (B) Mucosa model.

Fig. 2. Endoscopic submucosal dissection (ESD) in the G-Master. (A) Pseudolesion with a diameter of 30 mm marked on a mucosal sheet. (B) Injection of glycerol with indigo carmine. (C, D) Pre-cut using a dual knife. (E–K) Mucosal incision and submucosal dissection using an IT-2 knife. (L) Ulceration after ESD.

Fig. 3. Area measurement of the resected specimens using ImageJ.

Fig. 4. Raw plot of resection speeds for the four trainees.

Fig. 5. CUSUM plot of resection speed for the four trainees. CUSUM, cumulative sum.

Graphical abstract