Instrument-based calibration and remote control of intraoperative ultrasound for robot-assisted surgery

Intraoperative transrectal ultrasound (TRUS) has the potential to improve the outcomes of robotic-assisted laparoscopic radical prostatectomy (RALRP), a common treatment for prostate cancer. Intraoperative TRUS is currently difficult to implement in RALRP because a dedicated assistant with access to the patient is required. Previously described robotic TRUS probe manipulators overcome this limitation but require the surgeon to frequently interrupt their operation to reposition the TRUS probe under remote control. A new method for automatically tracking existing da Vinci surgical instruments with a TRUS imaging plane is presented, based on a rigid registration of the kinematic frames of the da Vinci system and the robotic TRUS probe manipulator. This registration is accomplished by identifying fiducial points on a tissue surface using the tip of a da Vinci manipulator, and does not require any external tracking system. Phantom validation shows an average registration error of 0.95 ± 0.38 mm based on manually locating the manipulator tips in TRUS images. This corresponds to an average tracking error of approximately 1 degree when rotating a parasagittal TRUS imaging plane to track a da Vinci manipulator.