Computational Modelling of Ultrasonic Propagation of a HIFU Transducer in Ligament and Cartilage

Bone tumors have been one of the most aggressive cancers that exist. Although conventional therapies are aggressive, alternative therapies for their treatment have emerged in recent years, one of them given for ultrasound thermal ablation. The use of ultrasound for cancer treatment is given by HIFU to achieve ablation temperatures into the affected area. This work presents two parametric studies of the acoustic propagation for a HIFU transducer for its evaluation in soft bone media: cartilage and ligament. In the first study, placement distances between the transducer and a single tissue were modified. Also, the tissue thickness was varied in order to find the best thicknesses that would allow the acoustic energy to go through the tissue and thus make a more complex model with both structures. Two different frequencies were evaluated: 3 and 4 MHz. The second study consisted in evaluating the best tissues thicknesses obtained from the previous one, but placing both tissues (one behind the other). The data shown that thicknesses of 2 mm in ligament and 0.8-1.6 mm in cartilage, for both frequencies, had better results. For this purpose, a distance of 70 mm between transducer and tissue presented the best values.