Ex vivo determined experimental correction factor for the ultrasonic source term in the bioheat equation

Cortela, Guillermo; Pereira, Wagner Coelho de Albuquerque; Negreira, Carlos

doi:10.1016/j.ultras.2017.07.008

Cited by 6 publications

(10 citation statements)

References 14 publications

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“…Thus, in the present work the Pennes' bio‐heat transfer equation 71 (Equation 4) was used to calculate the temperature field in the phantom. Our results were compared to published experimental and simulated measurements, which showed a good approximation that this model has in different hyperthermia processes, as described in 10,15,48,72

ρ c_{p} \frac{\partial T}{\partial t} goodbreak= \nabla \cdot ((), k \nabla T) goodbreak+ ρ_{b} c_{b} ω_{b} ([], T_{b} goodbreak- T ((), r, z, t)) goodbreak+ Q_{m} goodbreak+ Q in normalΩ for t > 0

where, c p is the specific heat, k is the thermal conductivity, c b is the blood specific heat, ρ b is the blood density, T is the tissue temperature, T b is the blood temperature, ω b is the blood perfusion rate, Q is the external heat source calculated from Equation (2), Q m is the metabolic heat source, and

normalΩ = ({},, 0 < r < L_{r}, 0 < z < L_{z})

is the domain.…”

Section: Mathematical Model Of the Forward Problemmentioning

confidence: 80%

“…The physical properties of the models were T s = 309.95 K, T f = 297.15 K, h f = 10.0 W m −2 K −1 , t = 200 s, c = 1480 m s −1 in water and 998 m s −1 in silicone. In the bioheat transfer model, the thermal properties of the biological tissue Q m , c b , ρ b , and ω b are zero because we chose the simulated domain as a solid material 10 . This assumption is possible because the differences in the temperature profile are almost negligible, that is, the higher difference was 0.25°C, which indicates that it is possible to use the simplified model.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 3 shows simulated temperature measurements, and our numerical simulation with/without vascularity where the c b = c p , ρ b = ρ , ω b = 0.0005 s −1 , and Q m = 4200 W m −3 37,40 . The results of the model from Reference [10] is also shown. These results were obtained from Equations (1)–(4) using the finite‐difference forward‐time centered‐space method and compared to experimental data.…”

Section: Resultsmentioning

confidence: 99%

“…The absorbed ultrasound energy Q is calculated by Equation (2) and the sound hard boundary condition (wall) at the domain is given by Equation (3).

Q goodbreak= 2 italicαI goodbreak= 2 α (||, Re ((), \frac{1}{2} p boldv))

where, I , is the acoustic intensity magnitude, α is the absorption coefficient and v is the acoustic particle velocity vector 10

goodbreak- boldn \cdot ((), goodbreak- \frac{1}{ρ} \nabla p) 0 < z < L_{z} goodbreak- L_{r} < r < goodbreak- L_{t} and L_{t} < r < L_{r}

where, L r and L z are the domain lengths in the r and z directions, L t is the domain length of the transducer.…”

Section: Mathematical Model Of the Forward Problemmentioning

confidence: 99%

“…High‐Intensity Focused Ultrasound (HIFU) is a promising method that uses an ultrasound transducer to perform hyperthermia by focusing the energy transducer on a specific area 1–23 . This procedure can be performed without anesthesia and on an outpatient basis because it is possible to adjust the frequency and the intensity of the transducer, as well as the duration of treatment exposure.…”

Section: Introductionmentioning

confidence: 99%

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Parameter estimation in high‐intensity focused ultrasound therapy

Cardenas

Varon

Cárdenas

2022

Numer Methods Biomed Eng

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Hyperthermia using High‐Intensity Focused Ultrasound (HIFU) is an acoustic therapy for cancer treatment. This technique consists of an increase in the temperature field of the tumor to achieve coagulative necrosis and immediate cell death. Therefore, for having a successful treatment, the physical problem requires to know several properties due to the high variability from individual to individual, or even for the same individual under different physiological conditions. This article presents a numerical simulation of hyperthermia therapy for cancer treatment using HIFU, as well as the estimation of parameters that influence the physical problem. Two mathematical models were considered to solve the forward problem. The acoustic model based on acoustic pressure performs a frequency‐domain study, and the bioheat transfer model a time‐dependent study. These models were solved using Comsol Multiphysics® software in a 2D‐axisymmetric rectangular domain to determine the temperature field. Parameter estimation was coded in Matlab Mathworks® environment using a Bayesian approach. The Markov Chain Monte Carlo method by the Metropolis–Hastings algorithm was implemented, and the simulated temperature measurements were considered. Results suggest that specific HIFU therapy can be performed for each patient by estimating appropriate parameters for cancer treatment and provides the possibility to define procedures before and during the treatment.

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