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Proceedings Paper

Interstitial doppler OCT monitoring of microvascular shutdown during photodynamic therapy in a Dunning prostate model: irradiance rate dependences
Author(s): Beau A. Standish; Xiao Jin; Jurek Smolen; Adrian Mariampillai; Nigel R. Munce; I. Alex Vitkin; Victor X. D. Yang
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Paper Abstract

Microcirculatory changes, such as vascular shutdown, may be a predictor to the therapeutic efficacy of photodynamic therapy (PDT). The aim of this study was to measure the tumour vascular response to varying irradiance rates during PDT deep within prostate tumour xenograft, via interstitial Doppler optical coherence tomography (DOCT). DOCT provides micron-scale spatial resolution allowing visualization of structures at near histological levels, and yields flow velocity resolution of ~20 μm/s. Current in vivo DOCT imaging probes are limited to intraluminal and near-surface sites. To improve the accessibility of DOCT to anatomically relevant sites deep within the body (e.g., prostate), an interstitial (IS) needle (~700μm diameter) probe was developed for minimally invasive monitoring of the microvascular response to PDT (irradiance administered superficially) within tumour tissue. Rats were given a photosensitizer drug, Photofrin, and 20-24 h later the tumours were exposed to light (635nm) with an irradiance rate of 8-133 mW/cm2 for 25 minutes to a total irradiance of 12-200 J/cm2. Results illustrated different rates of vascular shutdown within the tumour as imaged by IS-DOCT, related to the administered PDT irradiance rate and total irradiance. Controls (probe only, probe + light) showed no significant microvascular changes. IS-DOCT was able to detect and monitor microvascular changes during PDT. Microvascular shutdown occurred at different rates and showed correlation with PDT light dose and irradiance rate. These dependencies may play an important role in PDT treatment planning, feedback control for treatment optimization, and post treatment assessment.

Paper Details

Date Published: 17 October 2006
PDF: 9 pages
Proc. SPIE 6386, Optical Methods in the Life Sciences, 63860V (17 October 2006); doi: 10.1117/12.686277
Show Author Affiliations
Beau A. Standish, Univ. of Toronto (Canada)
Xiao Jin, Ontario Cancer Institute (Canada)
Jurek Smolen, Ontario Cancer Institute (Canada)
Adrian Mariampillai, Univ. of Toronto (Canada)
Nigel R. Munce, Univ. of Toronto (Canada)
I. Alex Vitkin, Univ. of Toronto (Canada)
Ontario Cancer Institute (Canada)
Radiation Oncology, Univ. of Toronto (Canada)
Victor X. D. Yang, Ontario Cancer Institute (Canada)
Ryerson Univ. (Canada)
Sunnybrook Health Science Ctr. (Canada)

Published in SPIE Proceedings Vol. 6386:
Optical Methods in the Life Sciences
Alexey A. Belyanin; Mostafa Analoui; Rebekah Anna Drezek; Claire F. Gmachl, Editor(s)

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