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Influence of metal screens on contrast in megavoltage x‐ray imaging
Author(s) -
Droege Ronald T.,
Bjärngard Bengt E.
Publication year - 1979
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 - 10.1118/1.594610
Subject(s) - contrast (vision) , optics , materials science , x ray , detector , x ray detector , radiography , computed radiography , nuclear medicine , physics , medicine , image quality , computer science , nuclear physics , artificial intelligence , image (mathematics)
The radiographic contrast of metal screen‐film detectors was investigated in order to determine the contrast capabilities of these detectors applied to megavoltage x‐ray imaging. The film contrast γ was found to be independent of the metal screen composition. Measurement of the scatter‐to‐primary film dose ratio in contact geometry demonstrated that a thick front screen of either 1.5 g/cm 2 copper or 2.5 g/cm 2 lead provides optimum contrast for the photon energies studied ( 60 Co and 4‐ and 8‐MV x rays). The same thicknesses were also found to be suitable in an air gap geometry which significantly improved the contrast compared to the contact geometry. Rear lead screens were found to provide no contrast improvement.