Time-resolved photoacoustic studies of vascular tissue ablation at three laser wavelengths

Abstract

Nanosecond-time-resolved photoacoustic transducers have been used to study the subthreshold and ablation response of vascular tissue irradiated with short laser pulses at 248, 308, and 532 nm. Attenuation coefficients, ablation thresholds, and ablation time scales can be obtained in this way providing new information on the laser-tissue interaction problem.

Quantitative spectroscopic photoacoustic imaging: a review

“…The key to this method is part (2), finding a solution to Eq. (50). This may be done in a number of ways.…”

“…The absorption coefficient, μ a , can be estimated either from the maximum amplitude of the signal, if the PA efficiency,Γ, and the incident fluence, Φ 0 , are known, or by fitting a curve to the exponentially decaying slope. [49][50][51] More recently, a frequency domain method for quantification of μ a has been proposed by Guo et al 52 It too assumes a homogeneous, nonscattering medium, and the starting point is that the measured data will be pðtÞ as given in Eq. (21) convolved with a frequency-dependent transfer function that will depend on both the acoustic absorption and the measurement system frequency response.…”

Near-Infrared Fluorescence Imaging and Spectroscopy in Random Media and Tissues

“…The first proposed optoacoustic applications aimed at sensitive detection of lesions in biological tissue based on measurements of arrival time of acoustic signals with no attention to the information contained in the profile of optoacoustic signals [18]. Later it was realized that the optoacoustic method with temporal resolution could be applied for monitoring of the laser energy deposition in optically absorbing media during the ablation process [19,20]. The lack of theoretical basis, however, did not allow the researchers to get quantitative results at that time.…”

Laser flash photography of cold cavitation-driven ablation in tissues

“…The time-resolved stress detection (TRSD) method consists of acoustic signal detection upon laser irradiation of absorbing medium [9][10][11][12][13]. TRSD technique allowed to study temporal behavior of stress transients in irradiated medium, and measure the recoil momentum upon ablation.…”