scholarly journals An Enhanced Numerical Model to Simulate Nonlinear Continuous Wave Ultrasound Propagation and the Resulting Temperature Response

2021 ◽  
Author(s):  
Shahram Mashouf
Keyword(s):  
Focused Ultrasound ◽  
Continuous Wave ◽  
Nonlinear Models ◽  
Operator Splitting ◽  
Temperature Response ◽  
High Intensity Focused Ultrasound ◽  
Propagation Model ◽  
Ultrasound Propagation ◽  
Ultrasound Field ◽  
Source Geometry

In this work a nonlinear CW ultrasound field propagation model based on a second-order operator splitting approach is studied and a number of significant enhancements are introduced and implemented. In this model the ultrasound field is calculated and propagated plane by plane and the effects of diffraction, nonlinearity and absorption are applied independently over incremental steps. This work completes the preceding works (Christopher and Parker 1991, Tavakkoli et al. 1998, Zemp et al. 2003, Williams et al. 2006) by introducing an arbitrary source geometry and excitation definition, full diffraction solution, enhanced pressure, enhanced power deposition rate and temperature prediction capabilities. The result is a particularly useful tool in carrying out simulations of high intensity focused ultrasound (HIFU) that includes temperature rise predictions. Comparisons are made with other codes in both linear and nonlinear regimes. Different dynamics of lesion formation are obtained in linear versus nonlinear models, specially at the onset of lesion creation during HIFU exposure.

scholarly journals An Enhanced Numerical Model to Simulate Nonlinear Continuous Wave Ultrasound Propagation and the Resulting Temperature Response

2021 ◽  
Author(s):  
Shahram Mashouf
Keyword(s):  
Focused Ultrasound ◽  
Continuous Wave ◽  
Nonlinear Models ◽  
Operator Splitting ◽  
Temperature Response ◽  
High Intensity Focused Ultrasound ◽  
Propagation Model ◽  
Ultrasound Propagation ◽  
Ultrasound Field ◽  
Source Geometry

In this work a nonlinear CW ultrasound field propagation model based on a second-order operator splitting approach is studied and a number of significant enhancements are introduced and implemented. In this model the ultrasound field is calculated and propagated plane by plane and the effects of diffraction, nonlinearity and absorption are applied independently over incremental steps. This work completes the preceding works (Christopher and Parker 1991, Tavakkoli et al. 1998, Zemp et al. 2003, Williams et al. 2006) by introducing an arbitrary source geometry and excitation definition, full diffraction solution, enhanced pressure, enhanced power deposition rate and temperature prediction capabilities. The result is a particularly useful tool in carrying out simulations of high intensity focused ultrasound (HIFU) that includes temperature rise predictions. Comparisons are made with other codes in both linear and nonlinear regimes. Different dynamics of lesion formation are obtained in linear versus nonlinear models, specially at the onset of lesion creation during HIFU exposure.

scholarly journals The feasibility of a noise elimination method using continuous wave response of therapeutic ultrasound signals for ultrasonic monitoring of high-intensity focused ultrasound treatment

2021 ◽  
Author(s):  
Ryo Takagi ◽  
Toshikatsu Washio ◽  
Yoshihiko Koseki
Keyword(s):  
Noise Reduction ◽  
High Intensity ◽  
Focused Ultrasound ◽  
Continuous Wave ◽  
High Intensity Focused Ultrasound ◽  
Hifu Treatment ◽  
Noise Elimination ◽  
Tissue Samples ◽  
Wave Response ◽  
Failure Conditions

Abstract Purpose In this study, the robustness and feasibility of a noise elimination method using continuous wave response of therapeutic ultrasound signals were investigated when tissue samples were moved to simulate the respiration-induced movements of the different organs during actual high-intensity focused ultrasound (HIFU) treatment. In addition to that, the failure conditions of the proposed algorithm were also investigated. Methods The proposed method was applied to cases where tissue samples were moved along both the lateral and axial directions of the HIFU transducer to simulate respiration-induced motions during HIFU treatment, and the noise reduction level was investigated. In this experiment, the speed of movement was increased from 10 to 40 mm/s to simulate the actual movement of the tissue during HIFU exposure, with the intensity and driving frequency of HIFU set to 1.0–5.0 kW/cm2 and 1.67 MHz, respectively. To investigate the failure conditions of the proposed algorithm, the proposed method was applied with the HIFU focus located at the boundary between the phantom and water to easily cause cavitation bubbles. The intensity of HIFU was set to 10 kW/cm2. Results Almost all HIFU noise was constantly able to be eliminated using the proposed method when the phantom was moved along the lateral and axial directions during HIFU exposure. The noise reduction level (PRL in this study) at an intensity of 1.0, 3.0, and 5.0 kW/cm2 was in the range of 28–32, 38–40, and 42–45 dB, respectively. On the other hand, HIFU noise was not basically eliminated during HIFU exposure after applying the proposed method in the case of cavitation generation at the HIFU focus. Conclusions The proposed method can be applicable even if homogeneous tissues or organs move axially or laterally to the direction of HIFU exposure because of breathing. A condition under which the proposed algorithm failed was when instantaneous tissue changes such as cavitation bubble generation occurred in the tissue, at which time the reflected continuous wave response became less steady.

A Fast Estimation Model for Angular Spectrum Based Focused Ultrasound Wave Simulation in Layered Tissue Media

2019 ◽  
Author(s):  
Tariq M. Arif ◽  
Zhiming Ji
Keyword(s):  
Focused Ultrasound ◽  
Heterogeneous Media ◽  
Gaussian Function ◽  
Homogeneous Medium ◽  
Temperature Response ◽  
Angular Spectrum ◽  
Simulation Models ◽  
High Intensity Focused Ultrasound ◽  
Ultrasound Wave ◽  
Estimation Model

Abstract High-Intensity Focused Ultrasound (HIFU) is a popular non-invasive therapeutic tool and widely used in many clinical settings. The simulation models used for HIFU responses are computationally expensive and time-consuming. Among many numerical HIFU simulation methods, the Rayleigh-Sommerfeld approach is considered to be a reliable one. However, Rayleigh-Sommerfeld is suitable for homogeneous medium, and for a heterogeneous media, many approximations should be made in order to reduce the calculation time. In this study, we propose a fast methodology for estimating focused ultrasound pressure-temperature field responses through layered tissue media. A computationally efficient nonlinear angular spectrum-based method that can address the effects of varying attenuations, reflections and refractions from tissue layers is implemented to calculate reference datasets. From the simulation datasets, a profile function coupled with a GUI code is constructed for estimating the pressure-temperature response by using a Gaussian function and a Genetic Algorithm. The HIFU response model illustrated in this study can be advantageous and time-effective when multiple simulations are required on a similar complex patient model, and it can be used to guide and reduce the sets of simulations required for planning HIFU treatment.

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