Premium
Limits of radial time constants to approximate thermal response of tissue
Author(s) -
Meijering Laurens J. T.,
van Gemert Martin J. C.,
Gijsbers Geert H. M.,
Welch Ashley J.
Publication year - 1993
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.1900130615
Subject(s) - time constant , irradiation , constant (computer programming) , laser , cylinder , optics , mechanics , thermal , materials science , pulse (music) , atomic physics , thermodynamics , physics , geometry , mathematics , nuclear physics , detector , computer science , electrical engineering , programming language , engineering
The time constant model, as an approximation to the bio‐heat equation, was tested for non‐ablating, deep penetrating (argon) laser beams in absorbing tissue phantoms (polyacrylamide) in air. Temperature responses were measured with a thermal camera, both during laser irradiation as well as after the laser beam was switched off. The radial time constant model was found to give a reasonable prediction (within 5%) of temperature rise for irradiation times of up to the order of one time constant. The cooling behavior of tissue could not be described by one single time constant. The time constant model was found to fit the early cooling rate (cooling time about equal to irradiation time) for laser pulse durations of up to one time constant. The late cooling rate turned out to be much slower than predicted by the radial time constant model, yet it was faster than the cooling rate predicted by the one‐dimensional instantaneous hot cylinder surface model. © 1993 Wiley‐Liss, Inc.