Design of a low power hybrid HIFU applicator for haemostasis based on acoustic propagation modelling

AbstractPurpose: The aim of this study was to design an applicator for haemostasis usage needing lower acoustic intensities (<880 W/cm2) than in previous devices intended for it, which is based on ultrasound propagation FEM modelling using a 2-MHz HIFU transducer. Materials and methods: Acoustic field characterisation and numerical simulations in water were performed with and without the proposed applicator. Parameters such as form factor, ellipsoidal shape ratio, and Euclidean distance were used (among others) to compare simulated data with transducer measurements without applicator. A low density polyethylene cone was manufactured from geometries validated from acoustic field modelling. The hollow cone was filled with 10% polyacrylamide gel as a coupling medium with liver phantom or chicken liver. Focal temperature was measured with a thermocouple embedded in the phantom for 1–20 W driving powers for 120 s. Standing wave ratios (SWR) were used as coupling indexes. Ex vivo experimentation in chicken live...