DETERMINATION OF THE TEMPERATURE FIELD DURING LASER COAGULATION of CHORIORETINAL COMPLEX WITH OPTOACOUSTIC IN VITRO
Alesya Valerevna ARDAMAKOVA1, Natalya Anatolevna FEDORUK1, Anton Pavlovich LYTKIN2, Andrey Viktorovich LARICHEV2, Vladimir Ivanovich SIPLIVYY3
1Research Institute of Eye Diseases
2Lomonosov Moscow State University
3Sechenov University
Keywords: коэффициент оптического поглощения, распределение температурного поля, лазеркоагуляция, оптоакустика, optical absorption coefficient, temperature field distribution, laser coagulation, optoacoustics
Abstract
The article describes a determination method of the laser radiation with specific parameters effect on the eye tissues based on optoacoustic probing. Low-power probing laser with 7-10 ns pulses generates acoustic waves at the aiming point. The waves propagate through the medium (saline in a cuvette) to acoustic receiver. The characteristics of the acoustic wave give basis for estimation of optical absorption coefficient - a parameter that determines temperature in the affected area after applying therapeutic laser. Calculation of the temperature pattern was performed using a three-dimensional thermal conductivity model that enabled determination of temperature distribution at any local point during coagulation and immediately after. To compare the results with pre-calculated temperature field values, direct temperature measurement was taken from the surface of the absorbing layer. The experiment was performed on six human chorioretinal tissue samples in vitro; the obtained optical absorption coefficient values did not exceed 120-300 cm-1 with maximum error margin of 20 %. The computational model was seen to be in good agreement with experimental thermocouple measurements.
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