Measurement of Ultrasonic Properties into Biological Tissues in the Hyperthermia Temperature Range

During hyperthermia treatments, for determining internal temperature by using non-invasive ultrasound estimation, it is necessary to know some tissue ultrasonic characteristics around the hyperthermia range. The aim of this work was to determine in detail the changes of some ultrasonic properties ( velocity and attenuation) of muscle, fat and liver tissues in the specific range of 26 degrees C to 50 degrees C. We proposed an experimental setup which allows minimizing the expansion effects in the biological samples. The ultrasonic signal passes through tissue and it is reflected by a 1-mm needle arrangement, inserted in the tissue sample. The results in the propagation speed behaviour, for the three studied tissues, appear to be quasi-linear with temperature changes. The attenuation coefficients are also presented for different temperatures.