A NOVEL MANIPULATOR FOR PROSTATE BRACHYTHERAPY: DESIGN AND PRELIMINARY RESULTS

The prostate is a small exocrine gland in men responsible for production of the liquid component of the seminal fluid. In North America, prostate cancer accounts to over 300,000 new cases and 40,000 deaths each year and it is the second leading cause of cancer death in men. Low-dose Rate (LDR) brachytherapy is gaining interest as a viable treatment option for prostate cancer due to its low side effects and high benefits. This procedure involves insertion of small seeds of radioactive isotopes into the gland to effect radiation therapy. The present manual approach for needle insertion and the inherent flexibility of brachytherapy needles makes it extremely difficult to achieve accurate and consistent dosimetry. In this paper, we present the design of a new 5 DOF manipulator capable of performing percutaneous needle insertion. The manipulator can perform orientation, insertion and rotation of the needle and linear motion of the plunger to drop radioactive seeds at targeted locations. Some of the key features of the manipulator are backdrivable joints, stationary actuators, redundant sensors and enhanced safety features. The manipulator will become an integral part of a system utilizing real-time 3D ultrasound image guided prostate brachytherapy. In this paper, we describe the mechanical design, construction and assembly of the manipulator.