EFFECTS OF 2 ULTRASOUND DEVICES AND ANGLES OF APPLICATION ON THE TEMPERATURE OF TISSUE PHANTOM

Ultrasound is a commonly used therapeutic modality for which there is little research on the effect of treatment dosage on the extent of tis sue heating. The purpose of this study was to investigate the effect o f two different ultrasound devices, angle of ultrasound application, a nd treatment time on the temperature oi a tissue phantom. Four trials were performed at four ultrasound application angles (90 degrees, 80 d egrees, 70 degrees and 60 degrees) with both an Excel UltraMax and a M ettler Sonicator 720. A continuous 1-MHz frequency at 2.0 W/cm(2) was administered for 5 minutes, with tissue phantom temperature recorded a t 1-minute intervals. The analysis of the data revealed significant ma in effects between ultrasound devices, angle of application, and treat ment times. Interactions were identified between ultrasound device and treatment times and angle of application and treatment times. Analysi s of simple effects revealed significant differences between ultrasoun d devices after 2, 3, 4, and 5 minutes of treatment and between treatm ent times and 80 degrees and 60 degrees angles of application. Maximal temperature increase after a 5-minute treatment was 2.025 degrees C. This level of tissue hearing falls below expected values and may not y ield therapeutic results. The thermal effects were noted to be greates t at 80 degrees and 90 degrees angles of application. Despite appropri ate calibration and identical treatment protocols, the two ultrasound devices yielded significantly different tissue phantom temperatures, w hich were notably lower than expected values. We concluded that direct monitoring of ultrasound device output and calculation of treatment d osage should occur on a routine basis, as treatment outcome will certa inly be affected by the actual dosage of ultrasonic energy.