FPGA-Based Portable Ultrasound Scanning System with Automatic Kidney Detection

Bedsides diagnosis using portable ultrasound scanning (PUS) offering comfortable diagnosis with various clinical advantages, in general, ultrasound scanners suffer from a poor signal-to-noise ratio, and physicians who operate the device at point-of-care may not be adequately trained to perform high level diagnosis. Such scenarios can be eradicated by incorporating ambient intelligence in PUS. In this paper, we propose an architecture for a PUS system, whose abilities include automated kidney detection in real time. Automated kidney detection is performed by training the Viola–Jones algorithm with a good set of kidney data consisting of diversified shapes and sizes. It is observed that the kidney detection algorithm delivers very good performance in terms of detection accuracy. The proposed PUS with kidney detection algorithm is implemented on a single Xilinx Kintex-7 FPGA, integrated with a Raspberry Pi ARM processor running at 900 MHz

High-Speed Photoacoustic Microscopy In Vivo

The overarching goal of this research is to develop a novel photoacoustic microscopy: PAM) technology capable of high-speed, high-resolution 3D imaging in vivo. PAM combines the advantages of optical absorption contrast and ultrasonic resolution for deep imaging beyond the quasi-ballistic regime. Its high sensitivity to optical absorption enables the imaging of important physiological parameters, such as hemoglobin concentration and oxygen saturation, which closely correlate with angiogenesis and hypermetabolism--two hallmarks of cancer. To translate PAM to the clinic, both high imaging speed and high spatial resolution are desired. With high spatial resolution, PAM can detect small structural and functional changes early; whereas, high-speed image acquisition helps reduce motion artifacts, patient discomfort, cost, and potentially the risks associated with minimally invasive procedures such as endoscopy and intravascular imaging. To achieve high imaging speed, we have constructed a PAM system using a linear ultrasound array and a kHz-repetition-rate tunable laser. The system has achieved a 249-Hz B-scan rate and a 0.5-Hz 3D imaging rate: over ~6 mm × 10 mm × 3 mm), over 200 times faster than existing mechanical scanning PAM using a single ultrasonic transducer. In addition, high-speed optical-resolution photoacoustic microscopy: OR-PAM) technology has been developed, in which the spatial resolution in one or two dimension(s) is defined by the diffraction-limited optical focus. Using section illumination, the elevational resolution of the system has been improved from ~300 micron to ~28 micron, resulting in a significant improvement in the 3D image quality. Furthermore, multiple optical foci with a microlens array have been used to provide finer than 10-micron lateral resolution--enabling the system to image capillary-level microvessels in vivo--while offering a speed potentially 20 times faster than previously existing single-focus OR-PAM. Finally, potential biomedical applications of the developed technology have been demonstrated through in vivo imaging of murine sentinel lymph nodes, microcirculation dynamics, and human pulsatile dynamics. In the future, this high-speed PAM technology may be adapted for clinical imaging of diabetes-induced vascular complications or tumor angiogenesis, or miniaturized for gastrointestinal or intravascular applications

Medical microprocessor systems

The practical classes and laboratory work in the discipline "Medical microprocessor systems", performed using software in the programming environment of microprocessors Texas Instruments (Code Composer Studio) and using of digital microprocessors of the Texas Instruments DSK6400 family, and models of electrical equipment in the environment of graphical programming LabVIEW 2010.Лабораторний практикум з програмування та побудови медичних мікропроцесорних систем, який викладено у навчальному посібнику допомагає накопичувати й ефективно використовувати отриману інформацію з теоретичного курсу на всіх стадіях навчального процесу, що є важливим для підготовки магістрів та необхідною ланкою у науковому пізнанні практичних основ біомедичної електроніки.The laboratory workshop on the programming and construction of medical microprocessor systems, which is outlined in the tutorial, helps to accumulate and effectively use the information obtained from a theoretical course at all stages of the educational process, which is important for the preparation of masters and a necessary link in the scientific knowledge of the practical basics of biomedicine.Лабораторный практикум по программированию и построению медицинских микропроцессорных систем, который изложен в учебном пособии помогает накапливать и эффективно использовать полученную информацию из теоретического курса на всех стадиях учебного процесса, что важно для подготовки магистров и является необходимым звеном в научном познании практических основ биомедицинской электроники

Front-end receiver for miniaturised ultrasound imaging

Point of care ultrasonography has been the focus of extensive research over the past few decades. Miniaturised, wireless systems have been envisaged for new application areas, such as capsule endoscopy, implantable ultrasound and wearable ultrasound. The hardware constraints of such small-scale systems are severe, and tradeoffs between power consumption, size, data bandwidth and cost must be carefully balanced. To address these challenges, two synthetic aperture receiver architectures are proposed and compared. The architectures target highly miniaturised, low cost, B-mode ultrasound imaging systems. The first architecture utilises quadrature (I/Q) sampling to minimise the signal bandwidth and computational load. Synthetic aperture beamforming is carried out using a single-channel, pipelined protocol in order to minimise system complexity and power consumption. A digital beamformer dynamically apodises and focuses the data by interpolating and applying complex phase rotations to the I/Q samples. The beamformer is implemented on a Spartan-6 FPGA and consumes 296mW for a frame rate of 7Hz. The second architecture employs compressive sensing within the finite rate of innovation (FRI) framework to further reduce the data bandwidth. Signals are sampled below the Nyquist frequency, and then transmitted to a digital back-end processor, which reconstructs I/Q components non-linearly, and then carries out synthetic aperture beamforming. Both architectures were tested in hardware using a single-channel analogue front-end (AFE) that was designed and fabricated in AMS 0.35μm CMOS. The AFE demodulates RF ultrasound signals sequentially into I/Q components, and comprises a low-noise preamplifier, mixer, programmable gain amplifier (PGA) and lowpass filter. A variable gain low noise preamplifier topology is used to enable quasi-exponential time-gain control (TGC). The PGA enables digital selection of three gain values (15dB, 22dB and 25.5dB). The bandwidth of the lowpass filter is also selectable between 1.85MHz, 510kHz and 195kHz to allow for testing of both architectural frameworks. The entire AFE consumes 7.8 mW and occupies an area of 1.5×1.5 mm. In addition to the AFE, this thesis also presents the design of a pseudodifferential, log-domain multiplier-filter or “multer” which demodulates low-RF signals in the current-domain. This circuit targets high impedance transducers such as capacitive micromachined ultrasound transducers (CMUTs) and offers a 20dB improvement in dynamic range over the voltage-mode AFE. The bandwidth is also electronically tunable. The circuit was implemented in 0.35μm BiCMOS and was simulated in Cadence; however, no fabrication results were obtained for this circuit. B-mode images were obtained for both architectures. The quadrature SAB method yields a higher image SNR and 9% lower root mean squared error with respect to the RF-beamformed reference image than the compressive SAB method. Thus, while both architectures achieve a significant reduction in sampling rate, system complexity and area, the quadrature SAB method achieves better image quality. Future work may involve the addition of multiple receiver channels and the development of an integrated system-on-chip.Open Acces

Computer-Assisted Algorithms for Ultrasound Imaging Systems

Ultrasound imaging works on the principle of transmitting ultrasound waves into the body and reconstructs the images of internal organs based on the strength of the echoes. Ultrasound imaging is considered to be safer, economical and can image the organs in real-time, which makes it widely used diagnostic imaging modality in health-care. Ultrasound imaging covers the broad spectrum of medical diagnostics; these include diagnosis of kidney, liver, pancreas, fetal monitoring, etc. Currently, the diagnosis through ultrasound scanning is clinic-centered, and the patients who are in need of ultrasound scanning has to visit the hospitals for getting the diagnosis. The services of an ultrasound system are constrained to hospitals and did not translate to its potential in remote health-care and point-of-care diagnostics due to its high form factor, shortage of sonographers, low signal to noise ratio, high diagnostic subjectivity, etc. In this thesis, we address these issues with an objective of making ultrasound imaging more reliable to use in point-of-care and remote health-care applications. To achieve the goal, we propose (i) computer-assisted algorithms to improve diagnostic accuracy and assist semi-skilled persons in scanning, (ii) speckle suppression algorithms to improve the diagnostic quality of ultrasound image, (iii) a reliable telesonography framework to address the shortage of sonographers, and (iv) a programmable portable ultrasound scanner to operate in point-of-care and remote health-care applications

Realtime photoacoustic microscopy in vivo with a 30-MHz ultrasound array transducer

We present a novel high-frequency photoacoustic microscopy system capable of imaging the microvasculature of living subjects in realtime to depths of a few mm. The system consists of a high-repetition-rate Q-switched pump laser, a tunable dye laser, a 30-MHz linear ultrasound array transducer, a multichannel high-frequency data acquisition system, and a shared-RAM multi-core-processor computer. Data acquisition, beamforming, scan conversion, and display are implemented in realtime at 50 frames per second. Clearly resolvable images of 6-µm-diameter carbon fibers are experimentally demonstrated at 80 µm separation distances. Realtime imaging performance is demonstrated on phantoms and in vivo with absorbing structures identified to depths of 2.5–3 mm. This work represents the first high-frequency realtime photoacoustic imaging system to our knowledge

Real-time digital signal processing system for normal probe diffraction technique

Ultrasonic systems are widely used in many fields of non-destructive testing. The increasing requirement for high quality steel product stirs the improvement of both ultrasonic instruments and testing methods. The thesis indicates the basics of ultrasonic testing and Digital Signal Processing (DSP) technology for the development of an ultrasonic system. The aim of this project was to apply a new ultrasonic testing method - the Normal Probe Diffraction method to course grained steel in real-time and investigate whether the potential of probability of detection (POD) has been improved. The theories and corresponding experiment set-up of pulse-echo method, TOFD and NPD method are explained and demonstrated separately. A comparison of these methods shows different contributions made by these methods using different types of algorithms and signals. Non-real-time experiments were carried out on a VI calibration block using an USPC 3100 ultrasonic testing card to implement pulse-echo and NPD method respectively. The experiments and algorithm were simulated and demonstrated in Matlab. A low frequency Single-transmitter-multi-receiver ultrasonic system was designed and built with a digital development board and an analogue daughter card to transmit or receive signals asynchronously. A high frequency high voltage amplifier was designed to drive the ultrasonic probes. A Matlab simulation system built with Simulink indicates that the Signal to Noise Ratio (SNR) can be improved with an increment of up to 3dB theoretically based on the simulation results using DSP techniques. The DSP system hardware and software was investigated and a real-time DSP hardware system was supposed to be built to implement the high frequency system using a rapid code generated system based on Matlab Simulink model and the method was presented. However, extra effort needs to be taken to program the hardware using a low-level computer language to make the system work stably and efficiently

Extraction of anthropological data with ultrasound

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.Human body scanners used to extract anthropological data have a significant drawback, the subject is required to undress or wear tight fitting clothing. This thesis demonstrates an ultrasonic based alternative to the current optical systems, that can potentially operate on a fully clothed subject. To validate the concept several experiments were performed to determine the acoustic properties of multiple garments. The results indicated that such an approach was possible. Beamforming is introduced as a method by which the ultrasonic scanning area can be increased, the concept is thoroughly studied and a clear theoretical analysis is performed. Additionally, Matlab has been used to demonstrate graphically, the results of such analysis, providing an invaluable tool during the simulation, experimental and results stages of the thesis. To evaluate beamfoming as a composite part of ultrasonic body imaging, a hardware solution was necessary. During the concept phase, both FPGA and digital signal processors were evaluated to determine their suitability for the role. An FPGA approach was finally chosen, which allows highly parallel operation, essential to the high acquisition speeds required by some beamforming methodologies. In addition, analogue circuitry was also designed to provide an interface with the ultrasonic transducers, which, included variable gain amplifiers, charge amplifiers and signal conditioning. Finally, a digital acquisition card was used to transfer data between the FPGA and a desktop computer, on which, the sampled data was processed and displayed in a coherent graphical manner. The beamforming results clearly demonstrate that imaging multiple layers in air, with ultrasound, is a viable technique for anthroplogical data collection. Furthermore, a wavelet based method of improving the axial resolution is also proposed and demonstrated

Synthetic aperture sonar

Synthetic aperture techniques have been applied very successfully for many years in astronomy and radar to obtain high resolution images, an outstanding example in recent years being the use in remote sensing satellite systems. In underwater acoustics, because of the inherent problems caused by random fluctuations in the signal path, the slow velocity of the acoustic wave and the unknown movements of the transducer as it traverses the aperture, the application of the synthetic aperture technique has mainly been limited to the very useful but rather inferior non-coherent technique known as side-scan sonar. However the rapid advances that are being made in micro-chip technology and fast digital signal processing, and the development in image processing algorithms has created renewed interest in the possible application of the synthetic aperture technique to underwater acoustics. This thesis describes such a study