RSNA 2003 

Abstract Archives of the RSNA, 2003


092-p

Robotically Aided Prostate Brachytherapy with 3D TRUS Guidance

Scientific Posters

Presented on December 3, 2003
Presented as part of L15: Physics Imaging Technologies: Various Topics

Participants

Zhouping Wei MS, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: Prostate brachytherpy plays an important role in the treatment of early-stage prostate cancer. However, it has been recognized that current prostate brachytherapy is susceptible to variability and is limited by pubic arch interference (PAI). Our purpose was to solve this problem by developing a robtically-aided system for prostate brachytherapy with 3D ultrasound image guidance because: 1. Ultrasound is the most suitable imaging modality for real-time guidance of seed implantation; 2. 3D US imaging with novel software tools will allow intra-operative brachytherapy procedures to be performed; 3. Robotic aids will free the procedure from the constraint of the rectilinear brachytherapy template and manual selection of the parallel needle trajectories used in current prostate brachytherapy, allowing oblique insertion trajectories as well as making the procedure faster. Methods and Materials: The system consists of 3D TRUS imaging system and a six degree-of-freedom robot. A one-hole template was installed onto the robot arm. By unifying the robotic coordinate system with the 3D TRUS image coordinate system, we could accurately and consistently insert the brachytherapy needle via the template hole into the target identified in the 3D TRUS image. The needle insertion accuracy was determined by using the system to target eight 0.8mm stainless-steel beads embedded in the agar phantoms. The accuracy was calculated by imaging the needle tip and calculating the deviations of the needle tip from the pre-insertion beads in the 3D TRUS image. System variability was determined from repeated targeting experiments. Principle component analysis was used to determine the variation of the needle tip location in 3D. Results: The mean targeting error was 1.07mm with a STD of 0.50mm. The mean displacement of the average needle position was 0.79mm with a STD of 0.32mm. The 3D 95% confidence ellipsoids were found to have total volumes ranging from 0.54mm3 to 1.92mm3, depending on the location of the beads with respect to the US probe and insertion distance. Conclusion: Targets in the 3D image coordinate system can be easily linked to the robotic system by using the coordinate transformation software. In this way the operator can simply control the robot to guide the needle to the target recognized in the 3D image. Therefore targeting using robotics and 3D imaging has a potential to reduce the operator-dependence seen in the current 2D TRUS-guided brachytherapy procedure, because targeting is more accurate and consistent, and oblique trajectories can avoid PAI.       Questions about this event email: zwei@imaging.robarts.ca

Cite This Abstract

Wei MS, Z, Robotically Aided Prostate Brachytherapy with 3D TRUS Guidance.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3102470.html