Maria Karzova

Lomonosov Moscow State University | MSU · Physics Faculty

A Mach-Zehnder interferometer is used to measure spherically diverging N-waves in homogeneous air. An electrical spark source is used to generate high-amplitude (1800 Pa at 15 cm from the source) and short duration (50 μs) N-waves. Pressure waveforms are reconstructed from optical phase signals using an Abel-type inversion. It is shown that the int...

Accurate measurement of high-amplitude, broadband shock pulses in air is an important part of laboratory-scale experiments in atmospheric acoustics. Although various methods have been developed, specific drawbacks still exist and need to be addressed. Here, a schlieren optical method was used to reconstruct the pressure signatures of nonlinear sphe...

The aim of this study is to show the evidence of Mach stem formation for very weak shock waves with acoustic Mach numbers on the order of 10−3 to 10−2. Two representative cases are considered: reflection of shock pulses from a rigid surface and focusing of nonlinear acoustic beams. Reflection experiments are performed in air using spark-generated s...

Acoustic fields of powerful ultrasound sources with Gaussian spatial apodization and initial excitation in the form of a periodic wave or single pulse are examined based on the numerical solution of the Khokhlov-Zabolotskaya-Kuznetsov equation. The influence of nonlinear effects on the spatial structure of focused beams, as well as on the limiting...

Extracorporeal shock wave therapy (ESWT) uses acoustic pulses to treat certain musculoskeletal disorders. In this paper the acoustic field of a clinical portable ESWT device (Duolith SD1) was characterized. Field mapping was performed in water for two different standoffs of the electromagnetic head (15 or 30 mm) using a fiber optic probe hydrophone...

Boiling histotripsy (BH) is a focused ultrasound technology that uses millisecond-long pulses with shock fronts to induce mechanical tissue ablation. The pulsing scheme and mechanisms of BH differ from those of cavitation cloud histotripsy, which was previously developed for benign prostatic hyperplasia. The goal of the work described here was to e...

No PDF available ABSTRACT Acoustic holography is frequently used for the characterization of fields generated by ultrasound transducers. For arrays with electronic focusing and beam steering, separate holograms are needed to represent the 3D field for each combination of array parameters. In this paper, we show that holograms for the field generate...

No PDF available ABSTRACT Previous studies have shown that the Sonalleve MR-HIFU clinical system can generate shocks of 80–105 MPa at the focus, which is sufficient for boiling histotripsy. Two versions of the system (V1 and V2) have therapeutic transducers that differ in focusing angle, arrangement of elements, and the size of a central opening. T...

No PDF available ABSTRACT The efficiency of various histotripsy approaches for mechanical tissue ablation has been reported to depend on tissue elastic properties. Here the efficiency of histotripsy liquefaction of human hematomas is investigated in dependence on their shear modulus value and retraction degree. Recalcified anticoagulated blood samp...

No PDF available ABSTRACT Boiling histotripsy (BH) is a promising technology for transrectal mechanical ablation of localized prostate cancer. BH uses sequences of milliseconds-long pulses to generate high-amplitude shocks in acoustic pressure waveforms at the focus, resulting in non-thermal liquefaction of pathological tissue. Despite successful p...

No PDF available ABSTRACT Recent studies have shown that nonlinear pulsed high-intensity focused ultrasound (pHIFU) is capable of inducing cavitation, without the need for contrast agents, to enhance drug delivery in tissues with poor perfusion. Here, acoustic characterization of a dual-mode linear array designed for image-guided cavitation-enhance...

No PDF available ABSTRACT The goal of this introductory talk is to present an overview of the software termed “HIFU beam” that has been designed for simulating HIFU fields generated by axially symmetric single-element transducers and annular arrays in flat-layered media that mimic biological tissues. Numerical models include the Khokhlov–Zabolotska...

No PDF available ABSTRACT Pulsed high-intensity focused ultrasound (pHIFU) is capable of inducing cavitation without the need for contrast agents, which can enhance drug transport in tissues with poor perfusion. We report on the experimental characterization of cavitation induced by a new dual-mode ultrasound arraydesigned for image-guided pHIFU th...

Large-volume soft tissue hematomas are a serious clinical problem, which, if untreated, can have severe consequences. Current treatments are associated with significant pain and discomfort. It has been reported that in an in vitro bovine hematoma model, pulsed high-intensity focused ultrasound (HIFU) ablation, termed histotripsy, can be used to rap...

High intensity focused ultrasound (HIFU) treatments typically involve the ablation of tissue volumes comprising multiple focal sites. One aspect of treatment planning involves the definition of a sequence of ultrasound pulses and corresponding focal sites as the sonication trajectory. Here, numerical simulations of the thermal effects of different...

“HIFU beam” is a freely available software tool that comprises a MATLAB toolbox combined with a user-friendly interface and binary executable compiled from FORTRAN source code HIFU beam. (2021). Available: http://limu.msu.ru/node/3555?language=en. It is designed for simulating high-intensity focused ultrasound (HIFU) fields generated by single-elem...

Pulsed focused ultrasound (pFUS) uses short acoustic pulses delivered at low duty cycle and moderate intensity to non-invasively apply mechanical stress or introduce disruption to tissue. Ultrasound-guided pFUS has primarily been used for inducing cavitation at the focus, with or without contrast agents, to promote drug delivery to tumors. When app...

No PDF available ABSTRACT Over the past decade, plans to develop a new generation of supersonic passenger aircrafts have spurred interest in sonic boom propagation in the atmosphere. New designs are focused on reducing its loudness on the ground. Sonic boom waves are affected by propagation in turbulence of the planetary boundary layer occurring in...

No PDF available ABSTRACT Measuring blast waves in laboratory-scale experiments using acoustical methods is a challenge. Optical methods provide an attractive possibility for recording pressure signatures of weak acoustic shocks. In this presentation, recent experiments for reconstructing pressure waveforms of spark-generated spherically divergent...

No PDF available ABSTRACT Interest to the problem of sonic boom propagation in atmosphere is growing in recent decade due to the development of new generation of supersonic business jets. Important nonlinear wave effects occur in the last kilometer above the ground where sonic boom wave interacts with turbulence of the planetary boundary layer. Foc...

Aim: of the study: demonstrate the feasibility of non-invasive mechanical disintegration of human prostate tissue using pulsed high-intensity focused ultrasound (pHIFU), a method termed boiling histotripsy. Materials and methods: An ultrasound experimental system was developed for producing localized mechanical lesions in ex vivo biological tiss...

The study aims to increase the accuracy of experimental methods for measuring acoustic radiation (AR) force acting on a millimeter-sized spherical scatterer in a liquid from a focused ultrasound beam [1], which was generated by a single-element, piezoceramic transducer positioned at the bottom of a water tank. The spherical scatterer was positioned...

The authors have recently shown that irregular reflections of spark-generated pressure weak shocks from a smooth rigid surface can be studied using an optical interferometer [Karzova, Lechat, Ollivier, Dragna, Yuldashev, Khokhlova, and Blanc-Benon, J. Acoust. Soc. Am. 145(1), 26–35 (2019)]. The current study extends these results to the reflection...

The paper presents the results of a numerical experiment comparing the rates of volumetric thermal ablation of bovine liver tissue ex vivo, generated by a multielement ultrasound array Sonalleve V1 3.0T (Philips Healthcare) using various exposure protocols. Pulsed sonications with the same time-average, but different peak power and duty cycle were...

The irregular reflection of weak acoustic shock waves, known as the von Neumann reflection, has been observed experimentally and numerically for spherically diverging waves generated by an electric spark source. Two optical measurement methods are used: a Mach-Zehnder interferometer for measuring pressure waveforms and a Schlieren system for visual...

The phenomenon of acoustic radiation force acting on solid spherical scatterers inside the field of a focused ultrasonic beam is experimentally studied. Nylon and glass beads are used as scatterers; the acoustic field is generated by a piezoceramic transducer of the megahertz frequency range in water. The angular spectrum of the ultrasonic beam, ob...

Acoustic radiation force (ARF) is successfully used in a recently proposed ultrasonic technology for kidney stone propulsion. The planning of the treatment requires calibration of ARF for stones of different dimensions and locations. However, such calibration remains a problem. Here, a method of measuring ARF acting on a mm-sized spherical object p...

Measurement-based modeling is gaining acceptance as a standard tool for characterizing the nonlinear fields of existing therapeutic ultrasound devices and designing new ones. Here, a freely available simulation tool is presented for modeling axially symmetric, strongly nonlinear HIFU beams with shocks in a layered propagation medium such as water a...

Irregular reflection of weak acoustic shock waves occurs under the framework of the von Neumann paradox. In this study, the influence of the surface roughness on the reflection pattern was studied experimentally using spark-generated spherically divergent N-waves of 1.4 cm length reflecting from rigid rough surfaces in air. Dimensions of the roughn...

Linear and nonlinear propagation of high amplitude acoustic pulses through a turbulent layer in air is investigated using a two-dimensional KZK-type (Khokhlov–Zabolotskaya–Kuznetsov) equation. Initial waves are symmetrical N-waves with shock fronts of finite width. A modified von Kármán spectrum model is used to generate random wind velocity fluctu...

Nonlinear propagation of short N-waves (wavelength of 1.4 cm) through a turbulent layer with outer scale of about 16 cm was simulated based on the 2D parabolic KZK-type equation. A modified von Kármán spectrum was used to generate random fluctuations of wind velocity associated with the presence of turbulence. Statistics of peak overpressure and sh...

Two theoretical approaches for simulating nonlinear focused ultrasound fields generated by a diagnostic convex array are compared. The first model is based on the three-dimensional Westervelt equation and describes the full structure of the array field with high accuracy. However, it requires great computational resources and is technically difficu...

Irregular reflection ofacoustic weak shockwaves (acoustic Mach numbers less than 0.01) is known as the von Neumann paradox and could not be described by the three-shock theory. In this work, nonlinear reflection regimes were studied experimentally using spark-generated spherically divergent N-waves reflecting from a plane rigid surface. Two optical...

Newer imaging and therapeutic ultrasound technologies may benefit from in situ pressure levels higher than conventional diagnosticultrasound. One example is the recently developed use of ultrasonic radiation force to move kidney stones and residual fragments out of the urinary collecting system. A commercial diagnostic 2.3 MHz C5-2 array probe has...

Vortex-wave beams are beams that carry angular momentum. Their specific feature is a ring-like transverse distribution of wave intensity with zero intensity at the axis. A method for generating an ultrasonic vortex beam by combining a single-element transducer and a phase plate with a nonuniform thickness is proposed. The method is examined theoret...

A method for measuring acoustic radiation force (ARF) acting on a mm-sized spherical object positioned on an axis of a focused ultrasound beam is proposed. The method is based on the balance between the ARF, gravity, and buoyancy forces acting on the object and initiating its movement when the value of the ARF crosses a certain threshold. Single-el...

New applications of ultrasound imaging may benefit from increased in situ pressure levels. However strong nonlinear propagation effects have not been studied in detail for fields generated by diagnostic transducers. Here we compare two modeling approaches for predicting shock formation in fields generated by a curvilinear imaging probe (C5-2). The...

The reflection of weak shockwaves on rigid boundaries at grazing angles was studied in different geometrical configurations. It was shown that even in the case of weak shocks, irregular reflection of N-waves can lead to the formation of a three shocks pattern with a Mach stem, a triple point above the rigid surface and an angle reflection which dif...

The local interactions occurring between incident and reflected shock waves in the vicinity of rigid surfaces are investigated. Both regular and irregular – also called von Neumann – regimes of reflection are studied, via experiment and numerical simulation. Shock waves are produced experimentally with a 20 kilovolts electrical spark source which a...

Mach stem is a well-known structure typically observed in the process of strong (acoustic Mach numbers greater than 0.4) step-shock waves reflection from a rigid boundary. However, this phenomenon has been much less studied for weak shocks in nonlinear acoustic fields where Mach numbers are in the range from 0.001 to 0.01 and pressure waveforms hav...

In the context of the scientific program SIMMIC supported by the French National Agency for Research (SIMI 9, ANR 2010 BLANC 0905 03), new wide band MEMS piezoresistive microphones have been designed and fabricated for weak shock wave measurements. The fabricated microphones have a high frequency resonance between 300 to 800 kHz depending on the me...

The reflection of a nonlinear spark-generated N-wave in air from a flat rigid surface is investigated experimentally. The pressure profile of the N-wave is reconstructed from optical measurements performed using a Mach–Zehnder interferometer. An irregular reflection is observed in the experiment; the evolution of a Mach stem is investigated, and th...

Numerical modeling is becoming an important metrological tool for accurate characterization of ultrasound fields generated by medical transducers in water and in situ. While acoustic propagation equations are well established, setting a boundary condition relevant to the experiment still remains a critical problem. Two methods differing in complexi...

In the context of both nonlinear acoustics, and downscaled acoustic or aero-acoustic experiments, the characterization of the high frequency response of microphones and pressure sensors remains a critical challenge. In the case of the design of new MEMS microphones and shock pressure sensors with response in the frequency range of 10 kHz–1 MHz, thi...

Newer imaging and therapeutic ultrasound technologies require higher in situ pressure levels compared to conventional diagnostic values. One example is the recently developed use of focused ultrasonic radiation force to move kidney stones and residual fragments out of the urinary collecting system. A commercial diagnostic 2.3 MHz C5-2 array probe i...

Mach stem is a well-known structure typically observed in the process of strong (acoustical Mach numbers greater than 0.4) step-shock waves reflection from a rigid boundary. However, this phenomenon has been much less studied for weak shocks in nonlinear acoustic fields where Mach numbers are in the range from 0.001 to 0.01 and pressure waveforms h...

Spark-generated spherical N-waves in air are measured by means of the Mach-Zehnder interferometer. A thin laser beam with sub-millimeter cross-section is used to obtain the highest time resolution. The light interference pattern is registered by a photodiode connected to a 10 MHz wideband amplifier. The inverse Abel transform is applied to the phas...

Extracorporeal shock wave therapy (ESWT) refers to the use of focused shock pulses to treat certain musculoskeletal disorders. Although the technology is used clinically, acoustic characteristics of ESWT fields and their relation to the bioeffects induced are not fully understood. In the present work, the acoustic field of a clinical ESWT device (D...

Physical mechanisms leading to saturation of various acoustic field parameters in nonlinear focused beams of periodic waves and single pulses were investigated numerically. A numerical algorithm based on the KZK equation was used in the simulations. Propagation of an initially harmonic wave and a single pulse (one period of a sine wave) emitted by...