Estimation of HIFU induced lesions in vitro: numerical simulation and experiment.

The heated necrotic element created by a single high intensity focused ultrasound exposure can be considered as the foundation of high intensity focused ultrasound ablation of tumour lesions. In this paper, we studied the effects of exposure dose and focal depth in tissue on heated necrotic elements, using numerical simulation and experiment. The acoustic field of one of the transducers for the Model-JC HAIFU focused ultrasound tumour therapeutic system was modeled using O Neill's equation, and then using this information together with Pennes' bio-heat-transfer-equation and finite difference techniques, the heated necrotic element was simulated numerically. The results showed that the theoretical predictions were basically in agreement with the experimental data for low exposures, but that the experimental values suddenly increased with the increasing exposure and exceeded the theoretical predictions. The element volume from the theoretical prediction and experiment for the heated necrotic element decreased with increasing focal depth in tissue for a given exposure, and the theoretical predictions were a little lower than the experimental ones. Therefore, heated necrotic elements created by high intensity focused ultrasound can be well predicted from a knowledge of ultrasonic biophysics theories.