Theoretical framework for quantitatively estimating harmonic intensity in focused ultrasound field using infrared thermometry

High-intensity focused ultrasound (HIFU) has been used successfully as new modality for the tumor treatments. Quantitative estimation of acoustic intensity at higher power output is important to the ablation planning, but the current approach is usually limited to the low power. Recently, infrared thermometry has been used to estimate acoustic intensity in the focused ultrasound field with the assumption of single frequency or in the linear mode. At higher power or in the therapy mode, nonlinear propagation effects will generate harmonics of the fundamental frequency. In this paper, a theoretical framework of quantitative method was introduced to estimate harmonic intensity in focused ultrasound field using infrared camera. The percentage differences between the derived results and the simulation are