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Radiographic information theory: Correction for x‐ray spectral distribution
Author(s) -
Brodie I.,
Gutcheck Robert A.
Publication year - 1983
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.595304
Subject(s) - detector , photon , radiography , fluence , optics , mammography , range (aeronautics) , x ray detector , pixel , spectral power distribution , energy (signal processing) , kerma , photon energy , physics , computer science , nuclear medicine , dosimetry , materials science , medicine , laser , cancer , breast cancer , nuclear physics , composite material , quantum mechanics
A more complete computational method is developed to account for the effect of the spectral distribution of the incident x‐ray fluence on the minimum exposure required to record a specified information set in a diagnostic radiograph. It is shown that an earlier, less rigorous, but simpler computational technique does not introduce serious errors provided that both a good estimate of the mean energy per photon can be made and the detector does not contain an absorption edge in the spectral range. Also shown is that to a first approximation, it is immaterial whether the detecting surface counts the number of photons incident from each pixel or measures the energy incident on each pixel. A previous result is confirmed that, for mammography, the present methods of processing data from the detector utilize only a few percent of the incident information, suggesting that techniques can be developed for obtaining mammograms at substantially lower doses than those presently used. When used with film–screen combinations, x‐ray tubes with tungsten anodes should require substantially lower exposures than devices using molybdenum anodes, when both are operated at their optimal voltage.