Magnetic resonance image-guided focused ultrasound robotic system with four computer-controlled axes with endorectal access designed for prostate cancer focal therapy

Background: A magnetic resonance image (MRI)-guided robotic system dedicated for prostate cancer (PC) was produced that carries a small spherically focused, single-element, ultrasonic transducer which can be potentially utilized endorectally. Materials and Methods: The developed robotic device utilizes four computer-controlled axes. An agar-based phantom was developed, which included a cavity that mimics the rectum geometry. Experiments with the system were performed in a 1.5T MRI system using the gel phantom. The transducer has a diameter of 18 mm, operates with 3 MHz, and focuses energy at 40 mm. Results: The functionality of the robot was assessed by means of magnetic resonance thermometry, demonstrating sufficient heating in both axes of operation (linear and angular). Conclusions: A functional MRI-guided robotic system was produced, which can create significant and controlled thermal exposures. The intention is to use the proposed device endorectally in the future for the focal treatment of PC.