Simulation and phantom validation of mild hyperthermia produced by a dual function ultrasound linear array

The prediction of the acoustic and temperature profiles is important for parameter optimization as a part of treatment planning for mild hyperthermia. A 3D acoustic field algorithm and a finite-difference time-domain (FDTD) method were combined in this study to calculate a 3D temperature profile in a tissue-mimicking phantom insonified by a dual function ultrasound linear array. In vitro validation was accomplished by using a fluorescent dye encapsulated in thermally-sensitive liposomes and an optical imaging system. For the single-beam insonation mode, the 39°C contour (by simulation) and dye release area (in vitro) were 7.0 by 4.5 mm and 7.6 by 6.7 mm in the elevation and lateral directions, respectively. For the scanned beam insonation mode, the 39°C contour and dye-release area were 12.0 by 11.4 mm and 12.2 by 11.6 mm in the elevation and lateral directions, respectively. The scanned-beam insonation mode showed a similar spatial extent of heating between simulation and in vitro experiments.