13 February 2007 Amplitude decay of photoacoustic signals in biological tissue when irradiated by nanosecond laser pulses
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Abstract
In this paper, we report on sequential decreases in the amplitude of photoacoustic (PA) signals from nanosecond laser pulse irradiation of various samples. These samples include biological tissues, such as dental-enamel and chicken/turkey breast as well as some non-biological samples. Laser energy densities in the range of 80mJ/cm2 to 300mJ/cm2 were used in our experiments, typical of those used in PA imaging regimes. Induced temperature rises are modelled to show that the average temperature rise for each pulse in those biological tissues is less than one degree centigrade. Measurements reveal a rapid decay of photoacoustic signals within the first few laser pulses absorbed by the sample and this decay is irreversible in the short term. The phenomenon indicates that laser irradiation interacts with biological samples, causing long-term physical changes that can be attributed to a reduction of optical absorption within the samples.
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Richard J. Dewhurst, Richard J. Dewhurst, Teng Li, Teng Li, Grzegorz Gondek, Grzegorz Gondek, } "Amplitude decay of photoacoustic signals in biological tissue when irradiated by nanosecond laser pulses", Proc. SPIE 6437, Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics, 643723 (13 February 2007); doi: 10.1117/12.698887; https://doi.org/10.1117/12.698887
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