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Proceedings Paper

A hybrid deformable model for simulating prostate brachytherapy
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Paper Abstract

Ultrasound (US) guided prostate brachytherapy is a minimally invasive form of cancer treatment during which a needle is used to insert radioactive seeds into the prostate at pre-planned positions. Interaction with the needle can cause the prostate to deform and this can lead to inaccuracy in seed placement. Virtual reality (VR) simulation could provide a way for surgical residents to practice compensating for these deformations. To facilitate such a tool, we have developed a hybrid deformable model that combines ChainMail distance constraints with mass-spring physics to provide realistic, yet customizable deformations. Displacements generated by the model were used to warp a baseline US image to simulate an acquired US sequence. The algorithm was evaluated using a gelatin phantom with a Young's modulus approximately equal to that of the prostate (60 kPa). A 2D US movie was acquired while the phantom underwent needle insertion and inter-frame displacements were calculated using normalized cross correlation. The hybrid model was used to simulate the same needle insertion and the two sets of displacements were compared on a frame-by-frame basis. The average perpixel displacement error was 0.210 mm. A simulation rate of 100 frames per second was achieved using a 1000 element triangular mesh while warping a 300x400 pixel US image on an AMD Athlon 1.1 Ghz computer with 1 GB of RAM and an ATI Radeon 9800 Pro graphics card. These results show that this new deformable model can provide an accurate solution to the problem of simulating real-time prostate brachytherapy.

Paper Details

Date Published: 13 March 2006
PDF: 10 pages
Proc. SPIE 6141, Medical Imaging 2006: Visualization, Image-Guided Procedures, and Display, 61410Q (13 March 2006); doi: 10.1117/12.651913
Show Author Affiliations
David Levin, Univ. of Western Ontario (Canada)
Robarts Research Institute (Canada)
Aaron Fenster, Univ. of Western Ontario (Canada)
Robarts Research Institute (Canada)
Hanif M. Ladak, Univ. of Western Ontario (Canada)
Robarts Research Institute (Canada)

Published in SPIE Proceedings Vol. 6141:
Medical Imaging 2006: Visualization, Image-Guided Procedures, and Display
Kevin R. Cleary; Robert L. Galloway, Jr., Editor(s)

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