1st International and 10th National Iranian Conference on Bioinformatics
Home Accepted Papers
Extraction of temperature distribution of high intensity focused ultrasound: Nonlinear propagation
Paper ID : 1090-ICB10
Authors:
Manijhe Manijhe Mokhtari-Dizaji *
Tarbiat Modares University
Abstract:
Background: The aim of the study is the extraction of acoustic pressure distribution in the target tissue layers based on the nonlinear behavior of waves. The nonlinear behavior effect of high intensity focused ultrasound (HIFU) on the temperature distribution of the tissue was extracted and compared with the linear behavior.
Materials and Methods: The acoustic pressure field was calculated using the Westervelt equation and was coupled with Pennes thermal transfer equation. The simulations were performed for three layers of skin, fat, and muscle using Comsol software. The disagreement between two linear and nonlinear models was analyzed with Kolmogorov–Smirnov test. The pressure and temperature distributions were calculated in nonlinear model by changing the acoustical parameters of the transducer including; intensity, effective radiation area, focal length and sonication time.
Results: Model results were validated with experimental results with 98% correlation coefficient (p<0.05). There are not significantly different between the pressure amplitude and temperature distribution in linear and nonlinear models at low intensity (p>0.05), but with increasing intensity to 10 W/cm2, in nonlinear model, maximum pressure and maximum temperature increased 40% and 20% compared with linear model. For input intensities of 1.5, 2, 8 and 10 W/cm2, the maximum pressure (at focal point) increased 10, 12, 22, 40% and maximum temperature increased 1, 2,12,20% in nonlinear model compared to linear model. At 0.8 and 1.5 cm2 effective radiation area, the maximum temperature in nonlinear model increased from 43 to 79 °C. By decreasing the focal lengths from 10 to 7.5 mm, the maximum temperature increased from 45 to 87 °C.
Conclusion: It is concluded a change in the input parameters of the transducer, it can be very effective in treating. The results emphasize the effects of nonlinear propagation and acoustical radiation parameters to improve the HIFU treatment.
Keywords:
Simulation; Ultrasound; Nonlinear; Thermo-viscous Effect
Status : Paper Accepted (Poster Presentation)