Ultrasound imaging through aberrating layers

Whereas aberrating layers are typically viewed as an impediment to medical ultrasound imaging, they can, surprisingly, also be used to our benefit. As long as we can model the effect of an aberrating layer, we can utilize ‘model-based imaging’, the imaging technique explored throughout this thesis, to reconstruct ultrasound images where...

A Pitch-Matched Low-Noise Analog Front-End With Accurate Continuous Time-Gain Compensation for High-Density Ultrasound Transducer Arrays

This article presents a compact analog front-end (AFE) circuit for ultrasound receivers with linear-in-dB continuous gain control for time-gain compensation (TGC). The AFE consists of two variable-gain stages, both of which employ a novel complementary current-steering network (CCSN) as the interpolator to realize continuously variable gain....

Time Versus Frequency Domain full Waveform Inversion for Ultrasound Imaging

With full waveform inversion (FWI) all available information enclosed in the recorded wavefield - including multiple scattering, dispersion, and diffraction - is used to obtain accurate images showing quantitative information of the tissue parameters. These non-linear inversion methods are implemented either in the time or in the frequency...

A Tiled Ultrasound Matrix Transducer for Volumetric Imaging of the Carotid Artery

High frame rate three-dimensional (3D) ultrasound imaging would offer excellent possibilities for the accurate assessment of carotid artery diseases. This calls for a matrix transducer with a large aperture and a vast number of elements. Such a matrix transducer should be interfaced with an application-specific integrated circuit (ASIC) for...

Coding Mask Design for Single Sensor Ultrasound Imaging

We study the design of a coding mask for pulse-echo ultrasound imaging. We are interested in the scenario of a single receiving transducer with an aberrating layer, or ‘mask,’ in front of the transducer's receive surface, with a separate co-located transmit transducer. The mask encodes spatial measurements into a single output signal, containing...

A Variable-Gain Low-Noise Transimpedance Amplifier for Miniature Ultrasound Probes

This article presents a low-noise transimpedance amplifier (TIA) designed for miniature ultrasound probes. It provides continuously variable gain to compensate for the time-dependent attenuation of the received echo signal. This time-gain compensation (TGC) compresses the echo-signal dynamic range (DR) while avoiding imaging artifacts...

Model-based validation of a tracking algorithm to quantify strain in muscles from two-dimensional ultrasound images

Fascicle shear is theoretically a mechanism by which skeletal muscles lengthen. Existing ultrasound based techniques allow measurement of muscle architecture parameters, but not the quantification of shear strain. In this study, an algorithm that tracks the shear strain from ultrasound images using a continuum representation of the muscle was...

An Investigation of the Medical Ultrasound Image Sparse Spaces used for the Model-Based Imaging

In this thesis, we investigate a sparse basis for ultrasound images, so that we can use sparse regularization in imaging. Actually, there are few previous researches explicitly demonstrating that medical ultrasound images can be sparsified for some dictionary. We consider various orthogonal transforms such as wavelet transforms, cosine...

A synchronized phonocardiogram for shear wave elastography

Worldwide, cardiovascular diseases (e.g. coronary heart disease and stroke) are the leading cause of death. Early detection of cardiac failure symptoms and effective treatment can help reducing health care costs and predict cardiovascular events, which may prevent loss of quality of life, or even loss of life. This early recognition of imminent...

Intrinsically Passive Control for Ultrasound-guided Robotic Scanning of the Breast

Automated breast ultrasound imaging systems provide the ability to combine the high anatomical detail of preoperative imaging with real-time intraoperative imaging. Ultrasound imaging involves interaction between the transducer and the patient, which requires a compliant behaviour of the robot in manipulating the transducer. We present an energy...

An Element-Matched Electromechanical ΔΣ ADC for Ultrasound Imaging

This paper presents a power- and area-efficient approach to digitizing the echo signals received by piezoelectric transducer elements, commonly used for ultrasound imaging. This technique utilizes such elements not only as sensors but also as the loop filter of an element-level δσ analog to digital converter (ADC). The receiver chain is thus...

Semi-Controllable Compression Schemes for Ultrasound Imaging

The application of Compressive Sampling (CS) in the medical ultrasound has been widely studied in recent years with the growing requirement of reconstructing high-quality images with smaller data size. Most of the current studies with successful CS reconstruction are mainly focusing on the mathematical applications of CS theory in ultrasound...

Design of a pipelined time-to-digital Converter (TDC) suitable for transducer array channel multiplexing

Many fields need high performance time measurements, including particle detection, time-resolved imaging, transducer array channel multiplexing and other time of-flight systems. These measurements are often performed by means of time-to-digital converters(TDCs), that for these applications, require high resolution, accuracy, and throughput. This...

A Low-Power Area-Efficient SAR-Assisted Hybrid ADC for Ultrasound Imaging

This thesis presents a Low-Power Area-Ecient SAR-Assisted Hybrid ADC for ultra-<br/>sound imaging systems. This ADC combines a 5-bit SAR ADC per channel with a 4-bit single-slope ADC that produces the converter's LSBs and is implemented using shared hardware. The number of unit capacitors of the proposed ADC is about 1/16th of that of a 9-bit...

Beamforming for novel matrix arrays: Fresnel Zone Beamforming and Stolt Migration

Currently a lot of effort is put into developing matrix arrays which allow for volumetric imaging and new applications. There are however multiple problems. Compared to arrays currently in use which have in the order of 128 elements, matrix arrays can easily contain 1000 to 10000 elements. If all elements would be connected independently, the...

Ultrasound imaging for quantitative evaluation of magnetic density separation

This thesis is dedicated to an investigation of the potential and technological possibilities of an inline ultrasound system as a quality control system for wet recycling of solid waste. The main targeted recycling technology is magnetic density separation (MDS), a novel technique that was investigated and technologically matured in a project...

Ultrasound imaging for quantitative measurement of immersed plastic waste particles

Ultrasound imaging techniques are proposed for measuring the shape and thickness of immersed waste particles (10-20 mm size) using a linear sensor array from a fixed position. For these purposes both the front and back surface of a particle needs to be reconstructed. Raw ultrasound pulse-echo and plane wave datasets and different imaging...