Motion Planning for Needle Insertion in Deformable Tissues

Medical procedures such as brachyterhapy seed implantation, biopsies, and treatment injections require inserting a needle tip to a specific target location inside the human body. This is difficult because (1) needle insertion causes soft tissues to displace and deform, and (2) it is often difficult or impossible to obtain precise imaging data during insertion.

To facilitate training and planning for medical procedures such as prostate brachytherapy, we are developing an interactive simulation of needle insertion and radioactive seed implantation in soft tissues. We develop a 2D dynamic finite element model based on a reduced set of scalar parameters such as needle friction, sharpness, and velocity, where the mesh is updated to maintain element boundaries along the needle shaft and the effect of needle tip and frictional forces are simulated. The simulation achieves 24 frames per second for 1250 triangular elements on a 750MHz PC.

We are also developing a sensorless planning system for radioactive seed implantation that combines our simulation of needle insertion with numerical optimization to compute needle insertion offsets that compensate for tissue deformations. We apply the method to seed implantation during permanent seed prostate brachytherapy to minimize seed placement error in simulation without relying on real-time imaging.

(a) Human prostate with target implant location	(b) Needle insertion	(c) Needle reaches target
(d) Seed implanted at target	(e) Needle extraction	(f) Seed placement error
Simulation of needle insertion based on an ultrasound image of a human prostate. Frame (a) outlines the prostate and displays the target implant location (white cross), which is fixed in the world frame. The simulated needle is inserted and places a radioactive seed (small square) at the target (d). After needle retraction, the placement Error, the distance between the target and resulting seed location shown in (f), is 20% of the width of the prostate. Needle plans that compensate for tissue deformation can reduce placement errors like this that damage healthy tissue and fail to kill cancerous cells.

Publications/Presentations

1. Ron Alterovitz, Jean Pouliot, Richard Taschereau, I-Chow Joe Hsu, and Ken Goldberg, "Sensorless Planning for Medical Needle Insertion Procedures," in Proceedings of the 2003 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2003), Oct. 2003, pp. 3337-3343. (Finalist, IROS2003 Best Paper Award) (Download PDF)
2. Ron Alterovitz, Jean Pouliot, Richard Taschereau, I-Chow Joe Hsu, and Ken Goldberg, "Needle Insertion and Radioactive Seed Implantation in Human Tissues: Simulation and Sensitivity Analysis," in Proceedings of the 2003 IEEE International Conference on Robotics and Automation (ICRA 2003), Sept. 2003, pp. 1793-1799. (Download PDF)
3. Ron Alterovitz, Jean Pouliot, Richard Taschereau, I-Chow Joe Hsu, and Ken Goldberg, "Modeling Seed Misplacement by Simulating Tissue Deformations," American Brachytherapy Society (ABS) 24th Annual Meeting, New York, NY, May 2003.
4. Ron Alterovitz, Jean Pouliot, Richard Taschereau, I-Chow Joe Hsu, and Ken Goldberg, "Simulating Needle Insertion and Radioactive Seed Implantation for Prostate Brachytherapy," in Medicine Meets Virtual Reality 11 (MMVR11), J.D. Westwood et al. (Eds.), IOS Press, Jan. 2003, pp. 19-25. (Download PDF)
5. Ron Alterovitz and Ken Goldberg. Comparing Algorithms for Soft Tissue Deformation: Accuracy Metrics and Benchmarks. Technical Report (Draft), ALPHA Lab, UC Berkeley, June 2002. (Download PDF)

Related Projects

• Stochastic Motion Roadmaps for Planning with Motion Uncertainty
• Motion Planning for Steerable Medical Needles
• Medical Image Registration for Deformable Tissues