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Proceedings Paper

Linear feasibility algorithms for treatment planning in interstitial photodynamic therapy
Author(s): A. Rendon; J. C. Beck; Lothar Lilge
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Paper Abstract

Interstitial Photodynamic therapy (IPDT) has been under intense investigation in recent years, with multiple clinical trials underway. This effort has demanded the development of optimization strategies that determine the best locations and output powers for light sources (cylindrical or point diffusers) to achieve an optimal light delivery. Furthermore, we have recently introduced cylindrical diffusers with customizable emission profiles, placing additional requirements on the optimization algorithms, particularly in terms of the stability of the inverse problem. Here, we present a general class of linear feasibility algorithms and their properties. Moreover, we compare two particular instances of these algorithms, which are been used in the context of IPDT: the Cimmino algorithm and a weighted gradient descent (WGD) algorithm. The algorithms were compared in terms of their convergence properties, the cost function they minimize in the infeasible case, their ability to regularize the inverse problem, and the resulting optimal light dose distributions. Our results show that the WGD algorithm overall performs slightly better than the Cimmino algorithm and that it converges to a minimizer of a clinically relevant cost function in the infeasible case. Interestingly however, treatment plans resulting from either algorithms were very similar in terms of the resulting fluence maps and dose volume histograms, once the diffuser powers adjusted to achieve equal prostate coverage.

Paper Details

Date Published: 27 February 2008
PDF: 11 pages
Proc. SPIE 6845, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVII, 68450O (27 February 2008); doi: 10.1117/12.764275
Show Author Affiliations
A. Rendon, Univ. of Toronto (Canada)
Univ. Health Network (Canada)
J. C. Beck, Univ. of Toronto (Canada)
Lothar Lilge, Univ. of Toronto (Canada)
Univ. Health Network (Canada)

Published in SPIE Proceedings Vol. 6845:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVII
David Kessel, Editor(s)

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