PMID: 3749260Jul 1, 1986Paper

Generalised use of contrast degradation and contrast improvement factors in diagnostic radiology. Application to vanishing contrast

Physics in Medicine and Biology
G A CarlssonJ Persliden

Abstract

Although field area and object thickness are important parameters in comparisons of techniques for optimal reduction of scattered radiation to the image, they are in practice seldom varied. For this reason, we suggest that contrast degradation (CDF) and contrast improvement (CIF) factors be more frequently used and appropriately defined to make the dependence of CDF and CIF on field area (collimation) and object thickness (compression) explicit. Definitions are formulated and the results of experiments and Monte Carlo calculations (comprising effects of collimation, compression, air gap, antiscatter grid, detector thickness) cited to illustrate their usefulness. Currently used expressions for CIF (derived assuming monoenergetic radiation) lack a factor to account for the change in primary contrast caused by the antiscatter method when this affects the energy distribution of the transmitted primary photons (grids and compression) or the fractions of photon energy imparted to the detector (when comparing different detectors). Values of this factor are calculated for some cases. Also, the appropriate choice of physical quantity to be used in the formulae for CDF and CIF is discussed. The energy imparted to the detector is advocate...Continue Reading

References

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Citations

Jul 1, 1994·Medical & Biological Engineering & Computing·M SandborgG A Carlsson
Feb 24, 1999·Applied Radiation and Isotopes : Including Data, Instrumentation and Methods for Use in Agriculture, Industry and Medicine·G A CarlssonM Sandborg
Jan 1, 1988·Dento Maxillo Facial Radiology·E HelmrotS Ericson
Jan 1, 1992·Physics in Medicine and Biology·D R DanceG A Carlsson
Jul 15, 2015·Physics in Medicine and Biology·H Khodajou-Chokami, M Sohrabpour

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