Figure 2. Technical advantage of optical see-through head-mounted displays (OST-HMD) assisted needle biopsy for breast tumor: In conventional ultrasound-guided procedures, needle biopsy is performed while maintaining a posture facing the monitor of a fixed ultrasonic device, which restricts the doctor’s posture and movement (A, B). However, with this technique, CNB can be executed smoothly with no posture restrictions (C, D).