THE MONOPOLE-SOURCE SOLUTION FOR ESTIMATING TISSUE TEMPERATURE INCREASES FOR FOCUSED ULTRASOUND FIELDS

The monopole-source solution to the problem of estimating tissue tempe rature rise generated by a focused ultrasound beam is presented. The a coustic pressure field generated by a focused, continuous-wave ultraso und source using the acoustic monopole-source method is developed. The point-source solution to the linear bio-heat transfer equation is use d to calculate the axial, steady-state temperature increase for both c ircular and rectangular apertures. The results of the circular apertur e are compared with the temperature increase calculated using the heat ed-disc method and are shown to be in substantial agreement. Finally, the temperature increase generated by the circular aperture is compare d to that of the rectangular aperture for the same source power, apert ure surface area, operating frequency, and medium properties, and it i s shown that the rectangular source generates temperature increases le ss than those of the circular source under these conditions.