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Proceedings Paper

Optical-thermal light-tissue interactions during photoacoustic imaging
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Paper Abstract

Photoacoustic imaging (PAI) has grown rapidly as a biomedical imaging technique in recent years, with key applications in cancer diagnosis and oximetry. In spite of these advances, the literature provides little insight into thermal tissue interactions involved in PAI. To elucidate these basic phenomena, we have developed, validated, and implemented a three-dimensional numerical model of tissue photothermal (PT) response to repetitive laser pulses. The model calculates energy deposition, fluence distributions, transient temperature and damage profiles in breast tissue with blood vessels and generalized perfusion. A parametric evaluation of these outputs vs. vessel diameter and depth, optical beam diameter, wavelength, and irradiance, was performed. For a constant radiant exposure level, increasing beam diameter led to a significant increase in subsurface heat generation rate. Increasing vessel diameter resulted in two competing effects – reduced mean energy deposition in the vessel due to light attenuation and greater thermal superpositioning due to reduced thermal relaxation. Maximum temperatures occurred either at the surface or in subsurface regions of the dermis, depending on vessel geometry and position. Results are discussed in terms of established exposure limits and levels used in prior studies. While additional experimental and numerical study is needed, numerical modeling represents a powerful tool for elucidating the effect of PA imaging devices on biological tissue.

Paper Details

Date Published: 4 March 2014
PDF: 8 pages
Proc. SPIE 8936, Design and Quality for Biomedical Technologies VII, 893603 (4 March 2014); doi: 10.1117/12.2044379
Show Author Affiliations
Taylor Gould, U.S. Food and Drug Administration (United States)
Quanzeng Wang, U.S. Food and Drug Administration (United States)
T. Joshua Pfefer, U.S. Food and Drug Administration (United States)

Published in SPIE Proceedings Vol. 8936:
Design and Quality for Biomedical Technologies VII
Ramesh Raghavachari; Rongguang Liang, Editor(s)

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