Temperature Field FDTD Simulation of Self-Focusing and Electronic Phased Focusing in Human Body Tissues

High intensity focused ultrasound (HIFU) tumor therapy is a new treatment technique of solid tumors and attracts interest of many researchers. In this study, a three-dimensional computational model, associated with finite difference time domain (FDTD) and Pennes Bio-heat transfer equation, is presented for studying the differences of the temperature field between self-focusing and electronic phased focusing. The effects of frequency on the temperature field of two different focusing techniques were also touched. Our results demonstrated that the area of focal region formed by self-focusing technology obtained a significant reduction, with a relative decrease in the temperature rise of skin and subcutaneous adipose tissue. This decrease made it possible to obtain a lower occurrence of skin burning, compared with the electronic phased focusing technique. The computation also suggested that the actual focal length and the area of focal region were inversely proportional to the acoustic frequency, whereas the temperature rise of the skin is proportional to it.