Search results
Results from the WOW.Com Content Network
The axial resolution of the system can be improved by using a wider bandwidth ultrasound transducer as long as the bandwidth matches that of the photoacoustic signal. The lateral resolution of photoacoustic microscopy depends on the optical and acoustic foci of the system.
Photoacoustic imaging or optoacoustic imaging is a biomedical imaging modality based on the photoacoustic effect.Non-ionizing laser pulses are delivered into biological tissues and part of the energy will be absorbed and converted into heat, leading to transient thermoelastic expansion and thus wideband (i.e. MHz) ultrasonic emission.
Ocular OCT retinal thickness map, right eye Time-domain OCT of the macular area of a retina at 800 nm, axial resolution 3 μm Spectral-domain OCT macula cross-section scan. Optical coherence tomography (OCT) is a technique for obtaining sub-surface images of translucent or opaque materials at a resolution equivalent to a low-power microscope.
Ultrasound image showing the liver, gallbladder and common bile duct. Medical ultrasound uses high frequency broadband sound waves in the megahertz range that are reflected by tissue to varying degrees to produce (up to 3D) images. This is commonly associated with imaging the fetus in pregnant women. Uses of ultrasound are much broader, however.
This particular biomedical imaging modality is a combination of optical imaging, and ultrasound imaging. In other words, a photoacoustic (PA) image can be viewed as an ultrasound image in which its contrast depends on the optical properties, such as optical resolution of biomolecules like hemoglobin, water, melanin, lipids, and collagen.
The notion of acoustic microscopy dates back to 1936 when S. Ya. Sokolov [1] proposed a device for producing magnified views of structure with 3-GHz sound waves. However, due to technological limitations at the time, no such instrument could be constructed, and it was not until 1959 that Dunn and Fry [2] performed the first acoustic microscopy experiments, though not at very high frequencies.
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
In ultrasound systems, lateral resolution is usually much lower than the axial resolution. The poor lateral resolution in the B-mode image also results in poor lateral resolution in flow estimation. Therefore, sub pixel resolution is needed to improve the accuracy of the estimation in the lateral dimension.