The influence of initial temperature on ultrasonic hyperthermia measurements

Ultrasonic heating has become an interesting topic among scientists because of its biomedical applications. One of them is using an ultrasound-induced temperature rise in the hyperthermia procedure. In most reports on ultrasonic hyperthermia measurements, the information of initial temperature was neglected or was not given due diligence. The current research aimed to check the influence of initial temperature on the efficiency of ultrasound hyperthermia in tissue-mimicking agar-based phantoms doped with silica nanoparticles that acted as sonosensitizers - they increased the attenuation of ultrasound and, as a consequence, the heating efficiency. The results indicated that temperature rise after sonication with a frequency of 1 MHz and intensity of 2.5 IN/cm(2) was indeed lower, with statistical significance, when experiments started at higher temperatures, while ultrasonic attenuation, the main factor influencing the ultrasonic heating efficiency, remained the same. These results suggest that the initial temperature should be regarded as an important factor when ultrasonic hyperthermia experiments are designed. (C) 2020 The Authors. Published by Elsevier Ltd.