Application of biophantomes to evaluate the thermal effects of laser radiation with wavelengths of 970 nm and 1560 nm under different exposure modes

Abstract

Laser interstitial hyperthermia is an actively developing direction in intracerebral tumor surgery. The paper presents thermal effects in polyacrylamide biophantoms with bovine albumin and citrated blood under laser irradiation at 970 nm and 1560 nm. For laser irradiation, a surgical two-wave apparatus manufactured by IRE Polis was used. The phantom was irradiated through a quartz optical fiber 400 µm in diameter with an end exit. The result of irradiation of the phantom was its coagulation zone, which was visualized with a FLUM-LL fluorescent organoscope. Thermometry was carried out with a FLIRONE PRO for IOS thermal imager and a T-8 digital thermograph based on a laptop with thermal sensors placed in a phantom. The use of irradiation with a power of not more than 2 W in the coagulation mode, with a total energy dose of up to 120 J, made it possible to achieve a smooth rise in temperature to 88.0 °C. The dimensions of the coagulation zone under irradiation with a wave of 1560 nm were always larger than under irradiation with a wave of 970 nm, although the difference was not statistically significant (p=0,41). Thus, the average coagulation spot area for 970 nm radiation was 43.2 (39.3 – 47.1) mm 2 , and for 1560 nm – 99.4 (56.5-141.3) mm 2 . With total irradiation with two waves, the coagulation zone was larger if the radiation power of 1560 nm prevailed. When irradiated with a wave of 970 nm, the coagulation zone partially propagates posteriorly from the tip of the optical fiber, and 1560 nm coagulates the phantom anteriorly. The results obtained are of practical importance for laser hyperthermia of intracerebral tumors.