Comparison of finite element and heated disc models of tissue heating by ultrasound

This paper compares different techniques used to model the heating caused b y ultrasound (US) in a phantom containing a layer of bone mimic covered by agar gel. Results from finite element (FE) models are compared with those f rom two techniques based on the point-source solution to the bioheat transf er equation (BHTE): one in which the bone mimic is considered to be an abso rbing disc of infinitesimal thickness and the other in which the region thr ough which the US travels is considered to be a volume heat source. The FE results are also compared with experimental measurements. The results from the models differed by up to 40% compared with those from the FE model. Fur thermore, for the intensity distribution considered, which corresponds to t hat in the focal zone of a single-element transducer, the top hat distribut ion predicts a temperature rise 1.8 times greater than that for a more real istic one based on measured values. (C) 2000 World Federation for Ultrasoun d in Medicine & Biology.