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Proceedings Paper

Parameter determination for singlet oxygen modeling of BPD-mediated PDT
Author(s): Dayton D. McMillan; Daniel Chen; Michele M. Kim; Xing Liang; Timothy C. Zhu
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Paper Abstract

Photodynamic therapy (PDT) offers a cancer treatment modality capable of providing minimally invasive localized tumor necrosis. To accurately predict PDT treatment outcome based on pre-treatment patient specific parameters, an explicit dosimetry model is used to calculate apparent reacted 1O2 concentration ([1O2]rx) at varied radial distances from the activating light source inserted into tumor tissue and apparent singlet oxygen threshold concentration for necrosis ([1O2]rx, sd) for type-II PDT photosensitizers. Inputs into the model include a number of photosensitizer independent parameters as well as photosensitizer specific photochemical parameters ξ σ, and β. To determine the specific photochemical parameters of benzoporphyrin derivative monoacid A (BPD), mice were treated with BPDPDT with varied light source strengths and treatment times. All photosensitizer independent inputs were assessed pre-treatment and average necrotic radius in treated tissue was determined post-treatment. Using the explicit dosimetry model, BPD specific ξ σ, and β photochemical parameters were determined which estimated necrotic radii similar to those observed in initial BPD-PDT treated mice using an optimization algorithm that minimizes the difference between the model and that of the measurements. Photochemical parameters for BPD are compared with those of other known photosensitizers, such as Photofrin. The determination of these BPD specific photochemical parameters provides necessary data for predictive treatment outcome in clinical BPD-PDT using the explicit dosimetry model.

Paper Details

Date Published: 13 March 2013
PDF: 8 pages
Proc. SPIE 8568, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXII, 856810 (13 March 2013); doi: 10.1117/12.2003277
Show Author Affiliations
Dayton D. McMillan, Univ. of Pennsylvania (United States)
Colorado State Univ. (United States)
Daniel Chen, Univ. of Pennsylvania (United States)
Michele M. Kim, Univ. of Pennsylvania (United States)
Xing Liang, Univ. of Pennsylvania (United States)
Timothy C. Zhu, Univ. of Pennsylvania (United States)

Published in SPIE Proceedings Vol. 8568:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXII
David H. Kessel; Tayyaba Hasan, Editor(s)

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