SAR and temperature distributions of cylindrical ultrasound transducers for intracavitary hyperthermia

The purpose of this paper is to examine the heating patterns when a cylindrical ultrasound transducer is employed for the intracavitary hyperthermia treatments. The present study employs a simulation program based on a simplified power deposition model for infinitely long cylindrical ultrasound transducers. The distribution of SAR ratio is used to determine the heating pattern for a set of given parameters. The parameters considered are the ultrasound attenuation in the tissue, the cavity size, and the transducer eccentricity. The results show that the ultrasound attenuation in the tissue, the cavity size and the transducer eccentricity are the most influential parameters for the distribution of SAR ratio. A low frequency transducer located in a large cavity can produce a much better penetration. The cavity size is the major parameter affecting the penetration depth for a small cavity size such as interstitial hyperthermia. The heating pattern can also be dramatically changed by the transducer eccentricity and radiating sector. The findings of the present study comprehend whether or not a tumor is treatable as well as select the optimal driving frequency, the appropriate cavity size and the eccentricity of a cylindrical transducer for a specific treatment