Search results
Results from the WOW.Com Content Network
An ultrasonic transducer with high central frequency and broader bandwidth are chosen to obtain high axial resolution. The lateral resolution is determined by the focal diameter of the transducer. For instance, a 50 MHz ultrasonic transducer provides 15 micrometre axial and 45 micrometre lateral resolution with ~3 mm imaging depth.
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.
Superficial structures such as muscle, tendon, testis, breast, thyroid and parathyroid glands, and the neonatal brain are imaged at higher frequencies (7–18 MHz), which provide better linear (axial) and horizontal (lateral) resolution. Deeper structures such as liver and kidney are imaged at lower frequencies (1–6 MHz) with lower axial and ...
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.
Synthetic aperture ultrasound (SAU) imaging is an advanced form of imaging technology used to form high-resolution images in biomedical ultrasound systems. Ultrasound imaging has become an important and popular medical imaging method, as it is safer and more economical than computer tomography (CT) and magnetic resonance imaging (MRI).
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.
In fluorescence microscopy the excitation and emission are typically on different wavelengths. In total internal reflection fluorescence microscopy a thin portion of the sample located immediately on the cover glass is excited with an evanescent field, and recorded with a conventional diffraction-limited objective, improving the axial resolution.
The resulting mean axial and lateral point location errors on 2,412 of their randomly selected test images were 0.28 mm and 0.37 mm respectively. After this initial implementation, the applications of deep learning in PACT have branched out primarily into removing artifacts from acoustic reflections, [ 9 ] sparse sampling, [ 10 ] [ 11 ] [ 12 ...