Three-dimensional ultrasound guidance and robot assistance for prostate brachytherapy

Abstract

Current transperineal prostate brachytherapy uses transrectal ultrasound (TRUS) guidance and a template at a fixed position to guide needles along parallel trajectories. However, pubic arch interference (PAI) with the implant path obstructs part of the prostate from being targeted by the brachytherapy needles along parallel trajectories. To solve the PAI problem, some investigators have explored other insertion trajectories, such as oblique, but the parallel trajectory constraints in current brachytherapy procedure also do not allow oblique insertion. This chapter describes a robot-assisted, threedimensional (3D) TRUS guided approach to solve this problem. Our prototype consists of a commercial robot, plus a 3D TRUS imaging system comprising an ultrasound machine, image acquisition apparatus using 3D TRUS image reconstruction, and display software. The robot positions the needle before insertion, but the physician inserts the needle into the patient's prostate. By unifying the robot, ultrasound transducer, and the 3D TRUS image coordinate systems, the position of the template hole can be accurately related to the 3D TRUS image coordinate system, allowing accurate and consistent insertion of the needle via the template hole into the targeted position in the prostate. © 2008 Springer US.