A time domain method to monitor temperature in microwave hyperthermia using ultrasound attenuation
01 Apr 2018-pp 1496-1499
TL;DR: This simulation study focused on estimating the spatio-temporal distribution of temperature from the estimates of attenuation of pulse-echo ultrasound RF data and was performed using the convolution model.
Abstract: Microwave heating is a well-known technique for delivering hyperthermia treatment to biological tissues. Temperature elevation during microwave tissue heating and feedback for real-time power control is commonly done using a limited number of invasive thermometry probes. Although ultrasound-based monitoring in real-time has been investigated for use with different ablation modalities, like radio frequency (RF) electrode, High Intensity Focused Ultrasound, its use in microwave hyperthermia is little reported. In this simulation study, we focused on estimating the spatio-temporal distribution of temperature from the estimates of attenuation of pulse-echo ultrasound RF data. The ultrasound simulation was performed using the convolution model. The temperature maps estimated using an algorithm based on tracking the changes in ultrasound attenuation is able to detect the spatial location of the hotspot with considerable precision. However, the current algorithm underestimates the isothermal regions and suffers from temperature dependent errors.
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05 Dec 2013
TL;DR: Diagnostic Ultrasound Imaging provides a unified description of the physical principles of ultrasound imaging, signal processing, systems and measurements that enable practicing engineers, students and clinical professionals to understand the essential physics and signal processing techniques behind modern imaging systems.
Abstract: Diagnostic Ultrasound Imaging provides a unified description of the physical principles of ultrasound imaging, signal processing, systems and measurements. This comprehensive reference is a core resource for both graduate students and engineers in medical ultrasound research and design. With continuing rapid technological development of ultrasound in medical diagnosis, it is a critical subject for biomedical engineers, clinical and healthcare engineers and practitioners, medical physicists, and related professionals in the fields of signal and image processing. The book contains 17 new and updated chapters covering the fundamentals and latest advances in the area, and includes four appendices, 450 figures (60 available in color on the companion website), and almost 1,500 references. In addition to the continual influx of readers entering the field of ultrasound worldwide who need the broad grounding in the core technologies of ultrasound, this book provides those already working in these areas with clear and comprehensive expositions of these key new topics as well as introductions to state-of-the-art innovations in this field. * Enables practicing engineers, students and clinical professionals to understand the essential physics and signal processing techniques behind modern imaging systems as well as introducing the latest developments that will shape medical ultrasound in the future* Suitable for both newcomers and experienced readers, the practical, progressively organized applied approach is supported by hands-on MATLAB code and worked examples that enable readers to understand the principles underlying diagnostic and therapeutic ultrasound* Covers the new important developments in the use of medical ultrasound: elastography and high-intensity therapeutic ultrasound. Many new developments are comprehensively reviewed and explained, including aberration correction, acoustic measurements, acoustic radiation force imaging, alternate imaging architectures, bioeffects: diagnostic to therapeutic, Fourier transform imaging, multimode imaging, plane wave compounding, research platforms, synthetic aperture, vector Doppler, transient shear wave elastography, ultrafast imaging and Doppler, functional ultrasound and viscoelastic models
1,170 citations
"A time domain method to monitor tem..." refers methods in this paper
...The estimated localized attenuation map was obtained from the ratio of the localized amplitudes of RF A-lines after and before heating as shown in equation (3) [16]....
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1,043 citations
"A time domain method to monitor tem..." refers background in this paper
...Computed tomography (CT) and magnetic resonance imaging (MRI) are useful for the follow-up assessment of ablation treatments [1]....
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TL;DR: In this article, the attenuation coefficient of fixed and fresh bovine and human soft tissues for various temperatures in the range 5 − 65°C was determined experimentally in both fresh and fixed Bovine soft tissues.
Abstract: Ultrasonic attenuation in the frequency range 1–7 MHz, and the speed of sound, were determined experimentally in both fresh and fixed bovine and human soft tissues for various temperatures in the range 5–65°C. At temperatures below 40°C the attenuation coefficient behaves similarly for fixed and fresh tissues where, at high frequencies, it has a negative dependence on temperature, the value at 20°C being about 21% higher than that at 37°C. As the frequency is reduced, the temperature coefficient of attenuation progressively decreases until, after passing a transition frequency (this varies with the tissue specimens but is around 1–2 MHz), a positive dependence on temperature may be observed. At temperatures above about 40°C, the attenuation coefficient of freshly excised tissues increases with temperature, whereas for fixed tissues the attenuation coefficient continues to decrease. These observations help to resolve a possible discrepancy evident in previous reports of the temperature dependence of attenuation. The speed of sound in non-fatty tissues increases with temperature and exhibits a maximum at around 50°C, while for fatty tissues a negative dependence is observed. The implications of this result for improved diagnostic procedures is discussed.
344 citations
"A time domain method to monitor tem..." refers background or methods in this paper
...An empirical relationship was obtained from the data of attenuation versus temperature, available in the literature for ex-vivo biological tissues [9, 12]....
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...These methods have the potential for producing highcontrast images, used for diagnosis and treatment monitoring [4-9]....
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...[9]J.C. Bamber and C.R. Hill, "Ultrasonic attenuation and propagation speed in mammalian tissues as a function of temperature",Ultrasound in medicine & biology, vol. 5, no. 2, pp. 149-157, Jan 1979....
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...Bamber and Hill [9] have also reported similar observations for a freshly excised and degassed bovine liver [7]....
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TL;DR: It was found that the rate at which the thermal dose was applied plays a very important role in the total attenuation absorption, and lower thermal dose rates resulted in larger attenuation coefficients.
Abstract: The effect of temperature and thermal dose (equivalent minutes at 43 °C) on ultrasonic attenuation in fresh dog muscle, liver, and kidney in vitro, was studied over a temperature range from room temperature to 70 °C. The effect of temperature on ultrasonic absorption in muscle was also studied. The attenuation experiments were performed at 4.32 MHz, and the absorption experiments at 4 MHz. Attenuation and absorption increased at temperatures higher than 50 °C, and eventually reached a maximum at 65 °C. The rate of change of tissue attenuation as a function of temperature was between 0.239 and 0.291 Np m−1 MHz−1 °C−1 over the temperature range 50–65 °C. A change in attenuation and absorption was observed at thermal doses of 100–1000 min, where a doubling of these loss coefficients was observed over that measured at 37 °C, presumably the result of changes in tissue composition. The maximum attenuation or absorption was reached at thermal dosages on the order of 107 min. It was found that the rate at which t...
281 citations
"A time domain method to monitor tem..." refers methods in this paper
...These methods have the potential for producing highcontrast images, used for diagnosis and treatment monitoring [4-9]....
[...]
TL;DR: A method has been developed which can predict the appearance and properties of B-scan images and a better understanding of the nature of pulse-echo images is gained and conclusions drawn regarding the range of system and tissue parameters over which these images convey information about the tissue structure.
Abstract: A method has been developed which can predict the appearance and properties of B-scan images. The theoretical basis for the tissue models used, and the assumptions made in the simulation concerning the nature of pulse-echo imaging, are discussed. A key feature of the simulation is the Fourier domain synthesis of the tissue model, which permits convenient specification of some statistical properties of a randomly inhomogeneous scattering medium. Other characteristics that may be specified include the ultrasonic pulse and beam shapes, and subsequent signal processing. Both the initial tissue model and the simulated B-scan image are displayed as grey-scale pictures, allowing visual comparison in the same way that clinical B-scans are currently observed. Preliminary results of applying the simulation are shown to have a number of features in common with clinical images and with scans of a test object. A better understanding of the nature of pulse-echo images is gained and conclusions drawn regarding the range of system and tissue parameters over which these images convey information about the tissue structure. The method may also be of use to determine optimum design of equipment for imaging and tissue characterisation, and to investigate the extent to which the acoustic structure of tissues can be described in terms of simple mathematical models.
237 citations
"A time domain method to monitor tem..." refers methods in this paper
...The tissue scattering function was modeled as a random inhomogeneous continuum of bulk adiabatic compressibility values [13]....
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...The latter was convolved with the point spread function (PSF) of a simulated imaging system to obtain RF data of the tissue [13]....
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...The method of US imaging, which is based on the 2-D simulation described by Bamber and Dickinson, was [13]....
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