Measurements of human milk fat content are essential for lactation care and research. We propose to quantify milk fat in non-homogenized human milk based on angular light scattering. Therefore, we measured the angular scattering profiles of milk from five donors using a goniometric light scattering setup. We also measured the milk fat globule (MFG) size distributions with 3D confocal laser scanning microscopy and use this as input in a Monte Carlo simulation. Both experimental and simulated angular scattering profiles are strongly dependent on fat concentration. The effect of the MFG size distribution on the scattering profiles will be discussed.
Timely, accurate assessment of atherosclerotic plaque composition in the carotid arteries to enable prevention of ischaemic stroke is currently an important topic in medical imaging. Photoacoustic imaging, which lacks ionizing radiation and foreign contrast agents, is attracting much interest in the field of non-invasive carotid plaque imaging. We present results of the characterization of our new system, based on a concave ultrasound transducer and optical fibre illumination, as well as multi-wavelength photoacoustic images of a PVCP-based phantom, supplemented with ultrasound plane wave images. The multi-wavelength photoacoustic imaging capability of the probe has potential for eventual carotid plaque imaging and quantification.
In view of the spreading of the Covid-19 virus, Real-Time Background Oriented Schlieren (RT-BOS) and backlight scatter imaging were used to visualize the air motion and droplets during talking, coughing, sneezing, singing, playing wind instruments. The effectiveness of personal protection like face masks and shields were studied. The distance of air (aerosols) spreading depends on the diameter/shape of the opening and air volume blown out per unit of time. Remarkably, the aerosol and droplet spreading of singing is similar or less than talking and even less for wind instruments. Any mouth mask although leaking air is effective in preventing droplets to spread.
We present a new laboratory setup for photoacoustic, transmission ultrasound and reflection ultrasound tomography. The system is based on a pair of independently rotating hemisphere segments on which are mounted acoustic transmitters and detectors. The interchangeability of the elements, as well as the ability to fully customise the acquisition protocol, allows for a considerable amount of flexibility in testing out different imaging approaches in both 2D and 3D. The current focus is the development of laser-induced ultrasound (LIUS) transmitters for use in tomographic imaging. We propose a transmitter design tuned for speed-of-sound mapping with a 1MHz centred response.
We present a 3D photoacoustic and ultrasound tomographic system intended for imaging of breast phantoms with the capacity to detect millimetric objects. The speciality of the ultrasound imaging part is that transmitters based on laser-induce ultrasound (LIUS) are used for acoustic generation. We describe the design and development of transmitters including an absorbing layer for photoacoustic generation.
We present laser-induced ultrasound (LIUS) imaging, using a conventional linear ultrasound probe as a receiver. The LIUS source consists of a 40 μm thick film of Carbon Black-doped PDMS. Illumination of this LIUS transmitter with a 10 ns pulsed Nd:YAG laser with a 10 Hz repetition rate leads to the generation of a short, unipolar ultrasound pulse as a consequence of the photoacoustic effect. Two synthetically focused imaging techniques will be presented: coherently compounded multi-angled plane wave imaging (PWI) and synthetic transmit aperture imaging (SAI) . In the PWI case a planar LIUS transmitter, matched in size to the conventional probe aperture, is used. In the SAI case, the same film is illuminated sequentially at different locations along the aperture by an array of multimode optical fibres. For both PWI and SAI a comparison between conventionally acquired and LIUS images is made, as well as a cross-comparison between PWI and SAI. Images of wire phantoms, speckle analysis and finally images of tissue-mimicking phantoms demonstrate the image quality and advantages offered by LIUS sources. Aside from generating shorter pulses for enhanced resolution, the continuous nature of the absorber and the illumination spot provides a cleaner, more homogeneous plane wave field. The outlook for these unconventional US sources and their relative advantages and disadvantages are discussed.
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