Simulation of thermal lesions in biological tissues irradiated by high-intensity focused ultrasound through the rib cage

Ilyin, S. A.; Bobkova, S. M.; Khokhlova, Vera A.; Гаврилов, Л. Р.

doi:10.3103/s1541308x11010122

Cited by 4 publications

(7 citation statements)

References 10 publications

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“…In the second set of simulations, ribs were present in the beam path as shown in figure 1. Following the model of previous papers (Bobkova et al 2010, Ilyin et al 2011, the ribs were represented as infinitely thin and absolutely absorbing parallel stripes. This simplified model does not account for actual 3D shapes of the ribs that would affect the overall diffraction and scattering field from the ribs.…”

Section: Numerical Simulation Of the Nonlinear Acoustic Field Of The ...mentioning

confidence: 99%

“…The ribs were represented as absolutely absorbing parallel strips; acoustic field modelling was based on the Rayleigh integral calculation and was limited by the linear approximation. The bioheat equation and thermal dose formulation were used to determine the size and the shape of lesions produced under these linear exposure conditions and the results of modelling were validated against experimental data (Ilyin et al 2011). Here, the 3D Westervelt model (Yuldashev and Khokhlova 2011) was generalized to simulate nonlinear propagation through ribs under the same geometrical configuration of sonications as in the previous paper (Bobkova et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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The role of acoustic nonlinearity in tissue heating behind a rib cage using a high-intensity focused ultrasound phased array

et al. 2013

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The goal of this study was to investigate theoretically the effects of nonlinear propagation in a high intensity focused ultrasound (HIFU) field produced by a therapeutic phased array and the resultant heating of tissue behind a rib cage. Three configurations of focusing were simulated: in water, in water with ribs in the beam path, and in water with ribs backed by a layer of soft tissue. The Westervelt equation was used to model the nonlinear HIFU field and a 1 MHz phased array consisting of 254 circular elements was used as a boundary condition to the model. The temperature rise in tissue was modelled using the bioheat equation, and thermally necrosed volumes were calculated using the thermal dose formulation. The shapes of lesions predicted by the modelling were compared with those previously obtained in in vitro experiments at low power sonications. Intensity levels at the face of the array elements that corresponded to formation of high amplitude shock fronts in the focal region were determined as 10 W·cm−2 in the free field in water and 40 W·cm−2 in the presence of ribs. It was shown that exposures with shocks provided a substantial increase in tissue heating, and its better spatial localization in the main focal region only. The relative effects of overheating ribs and splitting of the focus due to the periodic structure of the ribs were therefore reduced. These results suggest that utilizing nonlinear propagation and shock formation effects can be beneficial for inducing confined HIFU lesions when irradiating through obstructions such as ribs. Design of compact therapeutic arrays to provide maximum power outputs with lower intensity levels at the elements is necessary to achieve shock wave regimes for clinically relevant sonication depths in tissue.

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Section: Numerical Simulation Of the Nonlinear Acoustic Field Of The ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of acoustic nonlinearity in tissue heating behind a rib cage using a high-intensity focused ultrasound phased array

et al. 2013

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“…Moreover, the presence of the rib cage affects the HITU treatment planning. Firstly, the rib cage acts as an aberrator and decreases the focusing quality (Kennedy et al 2004, Liu et al 2007, Bobkova et al 2010, Ilyin et al 2011. Secondly, due to the high value of the absorption coefficient of the bone (Goss et al 1979), overheating of the ribs is induced during the treatment and radiates heat to the surrounding tissues.…”

Section: Effect Of the Rib Cagementioning

confidence: 99%

High-intensity therapeutic ultrasound: metrological requirements versus clinical usage

Aubry¹

2012

Metrologia

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High-intensity therapeutic ultrasound (HITU) is an appealing non-invasive, non-ionizing therapeutic modality with a wide range of tissue interactions ranging from transient permeabilization of cell membranes to thermal ablation. The ability to guide and monitor the treatment with an associated ultrasonic or magnetic resonance imaging device has resulted in a dramatic rise in the clinical use of therapeutic ultrasound in the past two decades. Nevertheless, the range of clinical applications and the number of patients treated has grown at a much higher pace than the definition of standards. In this paper the metrological requirements of the therapeutic beams are reviewed and are compared with the current clinical use of image-guided HITU mostly based on a practical approach. Liver therapy, a particularly challenging clinical application, is discussed to highlight the differences between some complex clinical situations and the experimental conditions of the metrological characterization of ultrasonic transducers.

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“…However, for a liver application, the rib cage affects the HIFU treatment planning. First of all, the rib cage acts as an aberrator and decreases the focusing quality (Kennedy et al 2002, Bobkova et al 2010, Liu et al 2007, Ilyin et al 2011. Second, due to the high value of the absorption coefficient of the bone (Goss et al 1979), an overheating on the ribs is induced during the treatment and radiates heat to the surrounding tissues.…”

Section: Introductionmentioning

confidence: 99%

Optimal transcostal high-intensity focused ultrasound with combined real-time 3D movement tracking and correction

et al. 2011

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Recent studies have demonstrated the feasibility of transcostal high intensity focused ultrasound (HIFU) treatment in liver. However, two factors limit thermal necrosis of the liver through the ribs: the energy deposition at focus is decreased by the respiratory movement of the liver and the energy deposition on the skin is increased by the presence of highly absorbing bone structures. Ex vivo ablations were conducted to validate the feasibility of a transcostal real-time 3D movement tracking and correction mode. Experiments were conducted through a chest phantom made of three human ribs immersed in water and were placed in front of a 300 element array working at 1 MHz. A binarized apodization law introduced recently in order to spare the rib cage during treatment has been extended here with real-time electronic steering of the beam. Thermal simulations have been conducted to determine the steering limits. In vivo 3D-movement detection was performed on pigs using an ultrasonic sequence. The maximum error on the transcostal motion detection was measured to be 0.09 ± 0.097 mm on the anterior-posterior axis. Finally, a complete sequence was developed combining real-time 3D transcostal movement correction and spiral trajectory of the HIFU beam, allowing the system to treat larger areas with optimized efficiency. Lesions as large as 1 cm in diameter have been produced at focus in excised liver, whereas no necroses could be obtained with the same emitted power without correcting the movement of the tissue sample.

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Simulation of thermal lesions in biological tissues irradiated by high-intensity focused ultrasound through the rib cage

Cited by 4 publications

References 10 publications

The role of acoustic nonlinearity in tissue heating behind a rib cage using a high-intensity focused ultrasound phased array

The role of acoustic nonlinearity in tissue heating behind a rib cage using a high-intensity focused ultrasound phased array

High-intensity therapeutic ultrasound: metrological requirements versus clinical usage

Optimal transcostal high-intensity focused ultrasound with combined real-time 3D movement tracking and correction

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