ALGEBRAIC RECONSTRUCTION OF SPATIAL DISTRIBUTIONS OF REFRACTIVE INDEX AND ATTENUATION IN TISSUES FROM TIME-OF-FLIGHT AND AMPLITUDE PROFILES.

James F Greenleaf, S. A. Johnson

Research output: Chapter in Book/Report/Conference proceedingChapter

5 Citations (Scopus)

Abstract

Two-dimensional distributions of refractive index and attenuation were measured in transverse sections through intact isolated organs, using reconstruction techniques. Profiles of time-of-flight (TOF) and/or amplitude of 10 MHz pulses through the specimen were obtained by rectilinearly scanning two opposing transducers along either side of the specimen in the plane of interest. The received pulses were digitized at a rate of one 8-bit sample per 10 ns for 512 samples, and were analyzed with a computer algorithm which calculated the TOF of the pulse to within plus or minus 10 ns and/or its amplitude. TOF's through tissue, normalized by TOF through water, were used to calculate velocity and, hence, refractive index within the specimen, using an algebraic reconstruction technique (ART). A similar approach was taken to calculate attenuation distributions. Images obtained represented acoustic velocities and/or attenuation in individual cross sections within the tissue specimen with a resolution of 64 by 64 elements ( less than 2 mm**2). The disadvantage of TOF and attenuation reconstruction is that transmission scanning is rquired. Advantages over B- and C-scan imaging are: (1) dynamic changes in receiver gain are not required; (2) attenuation occurs on only one traversal through tissue; and (3) the absolute values of important acoustic parameters (velocity and attenuation) are determined which may have significant diagnostic value.

Original languageEnglish (US)
Title of host publicationNatl Bur Stand Spec Publ
Pages109-119
Number of pages11
Edition453
StatePublished - Oct 1975
EventProc of Semin on Ultrason Tissue Charact, 1st, NBS - Gaithersburg, MD, USA
Duration: May 28 1975May 30 1975

Other

OtherProc of Semin on Ultrason Tissue Charact, 1st, NBS
CityGaithersburg, MD, USA
Period5/28/755/30/75

Fingerprint

Spatial distribution
Refractive index
Tissue
Scanning
Acoustic wave velocity
Transducers
Acoustics
Imaging techniques
Water

ASJC Scopus subject areas

  • Engineering(all)

Cite this

ALGEBRAIC RECONSTRUCTION OF SPATIAL DISTRIBUTIONS OF REFRACTIVE INDEX AND ATTENUATION IN TISSUES FROM TIME-OF-FLIGHT AND AMPLITUDE PROFILES. / Greenleaf, James F; Johnson, S. A.

Natl Bur Stand Spec Publ. 453. ed. 1975. p. 109-119.

Research output: Chapter in Book/Report/Conference proceedingChapter

Greenleaf, JF & Johnson, SA 1975, ALGEBRAIC RECONSTRUCTION OF SPATIAL DISTRIBUTIONS OF REFRACTIVE INDEX AND ATTENUATION IN TISSUES FROM TIME-OF-FLIGHT AND AMPLITUDE PROFILES. in Natl Bur Stand Spec Publ. 453 edn, pp. 109-119, Proc of Semin on Ultrason Tissue Charact, 1st, NBS, Gaithersburg, MD, USA, 5/28/75.
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abstract = "Two-dimensional distributions of refractive index and attenuation were measured in transverse sections through intact isolated organs, using reconstruction techniques. Profiles of time-of-flight (TOF) and/or amplitude of 10 MHz pulses through the specimen were obtained by rectilinearly scanning two opposing transducers along either side of the specimen in the plane of interest. The received pulses were digitized at a rate of one 8-bit sample per 10 ns for 512 samples, and were analyzed with a computer algorithm which calculated the TOF of the pulse to within plus or minus 10 ns and/or its amplitude. TOF's through tissue, normalized by TOF through water, were used to calculate velocity and, hence, refractive index within the specimen, using an algebraic reconstruction technique (ART). A similar approach was taken to calculate attenuation distributions. Images obtained represented acoustic velocities and/or attenuation in individual cross sections within the tissue specimen with a resolution of 64 by 64 elements ( less than 2 mm**2). The disadvantage of TOF and attenuation reconstruction is that transmission scanning is rquired. Advantages over B- and C-scan imaging are: (1) dynamic changes in receiver gain are not required; (2) attenuation occurs on only one traversal through tissue; and (3) the absolute values of important acoustic parameters (velocity and attenuation) are determined which may have significant diagnostic value.",
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