Methods for Increasing the Lateral Resolution of B-Scan
B-scan displays a picture of a cross-section through the body and is widely used in ultrasonic diagnosis. The main deficiency of B-scan is the low lateral resolution, which has its origin in the large diameter of the ultrasound beam.
The first system to be described is a synthetic aperture sonar system working at 2 MHz (λ = 0.75 mm in water) . The important features of the system and the optical processing are given. A second system uses an annular transducer for focussing the ultrasound beam over a depth of 20 cm. The side lobes are reduced by subtracting an echo signal from a second pulse which contains echoes from reflectors in the region of the side lobes only. All systems have a lateral resolution of 2–3 mm and are thus almost one order of magnitude better than conventional B-scan.
KeywordsPoint Spread Function Lateral Resolution Side Lobe Zone Plate Fresnel Zone Plate
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- 1.P.N.T. Wells, “Physical Principles of Ultrasonic Diagnosis” , (Academic Press, London, New York 1969).Google Scholar
- 3.F.L. Thurstone, W. McKinney, “Focused Transducer Arrays in an Ultrasonic Scanning System for Biologic Tissue” , in “Diagnostic Ultrasound” , C. C. Grossmann et al. Eds. (Springer Science+Business Media New York 1966), pp. 191–194.Google Scholar
- 8.D.W. Prine, “Synthetic Aperture Ultrasonic Imaging” , Proc. of the Symp. on Engineering Applications of Holography, Feb. 16–17, 1972, Los Angeles, Calif. , pp. 287–294.Google Scholar
- 9.R.J. Collier, C.B. Burckhardt, L.H. Lin, “Optical Holography” , (Academic Press, New York, London 1971) .Google Scholar
- 12.M. Abramowitz, I.A. Stegun, “Handbook of Mathematical Functions” , (Dover Publications Inc. , New York 1968) , p. 364.Google Scholar