Percutaneous Nephrolithotomy (PCNL) is a minimally invasive surgical procedure performed through a 1cm incision under ultrasound and fluoroscopy guidance for large renal stones removal. Patients who have undergone this procedure had shown decreased length of hospital stay, less morbidity, less pain, better preservation of the renal function and higher stone free rate. However, successful execution of PCNL is challenging due to respiratory movement of the patient’s kidney and involuntary motion of the surgeon. It relies heavily on manual control and experience, judgement and dexterity of a surgeon. Hence, a collaborative surgeon-robot system is proposed. A controller has been designed to allow the surgeon to maneuver the US probe to the desired position and proceed to perform other tasks in parallel.
Ultrasound imaging is preferred since it provides a real-time visualization during initial needle puncture. However, the image quality varies with scanning method. In order to achieve consistent ultrasound imaging, an ultrasound-guided visual serving method to track out-of-plane motion of the kidney stones is proposed. In addition, a control algorithm to maintain appropriate force between the ultrasound probe and the patient’s body after manual positioning will provide better image quality and reduces the burden on surgeons. The system aims to compensate involuntary and respiratory motions during the PCNL procedure.
Technology Features, Specifications and Advantages
The technology comprises an ultrasound-guided PCNL robot with translational and rotational motors, and an US probe mounted at the end. The surgeon could manoeuver the US probe to the desired position and proceed to perform other task in parallel. This is achieved by powering the robot into passive mode through force control schemes, where the sensor measures the interactive guiding force from the surgeon and transmit the force into the robot’s velocity to control the degree of movement during gross and fine motion of the US probe.
The robot also comprises a vision tracking capability to track the movement of the kidney to guide the needle and keep the US probe in contact with the patient’s skin throughout the procedure. In addition, the system also includes an algorithm on active contour model to reconstruct a 3D model from pre-operation CT images.
The targeted application for this system is in PCNL for renal stone operation. The system can be extended to a wider range of surgical procedures including heart and lung related procedures. Ultrasound imaging is favoured over fluoroscopy guided imaging for PCNL procedures since patient and clinical staff exposure to radiation is avoided.
With the use of ultrasound imaging instead of fluoroscopy guidance, patients avoid exposure to radiation which increases the risk of complications. The guided US probe and motion compensation robot reduces reliance on manual control, experience and dexterity, and ensure higher standard of healthcare delivery among surgeries. It also reduces the risk of multiple needle punctures that increase risk of bleeding and damage to nearby organs of a patient.