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Proceedings Paper

Intraoperative localization of brachytherapy implants using intensity-based registration
Author(s): Z. KarimAghaloo; P. Abolmaesumi; N. Ahmidi; T. K. Chen; D. G. Gobbi; G. Fichtinger
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Paper Abstract

In prostate brachytherapy, a transrectal ultrasound (TRUS) will show the prostate boundary but not all the implanted seeds, while fluoroscopy will show all the seeds clearly but not the boundary. We propose an intensity-based registration between TRUS images and the implant reconstructed from fluoroscopy as a means of achieving accurate intra-operative dosimetry. The TRUS images are first filtered and compounded, and then registered to the fluoroscopy model via mutual information. A training phantom was implanted with 48 seeds and imaged. Various ultrasound filtering techniques were analyzed, and the best results were achieved with the Bayesian combination of adaptive thresholding, phase congruency, and compensation for the non-uniform ultrasound beam profile in the elevation and lateral directions. The average registration error between corresponding seeds relative to the ground truth was 0.78 mm. The effect of false positives and false negatives in ultrasound were investigated by masking true seeds in the fluoroscopy volume or adding false seeds. The registration error remained below 1.01 mm when the false positive rate was 31%, and 0.96 mm when the false negative rate was 31%. This fully automated method delivers excellent registration accuracy and robustness in phantom studies, and promises to demonstrate clinically adequate performance on human data as well.

Paper Details

Date Published: 13 March 2009
PDF: 8 pages
Proc. SPIE 7261, Medical Imaging 2009: Visualization, Image-Guided Procedures, and Modeling, 726139 (13 March 2009); doi: 10.1117/12.812447
Show Author Affiliations
Z. KarimAghaloo, Queen's Univ. (Canada)
P. Abolmaesumi, Queen's Univ. (Canada)
N. Ahmidi, Queen's Univ. (Canada)
T. K. Chen, Queen's Univ. (Canada)
D. G. Gobbi, Queen's Univ. (Canada)
G. Fichtinger, Queen's Univ. (Canada)

Published in SPIE Proceedings Vol. 7261:
Medical Imaging 2009: Visualization, Image-Guided Procedures, and Modeling
Michael I. Miga; Kenneth H. Wong, Editor(s)

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