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Intensifying effect of metallic screens on the sensitivity of x‐ray films for 400‐kV bremsstrahlung photons
Author(s) -
Navon E.,
Dick C. E.,
Barnea G.
Publication year - 1991
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 - 10.1118/1.596725
Subject(s) - bremsstrahlung , photon , sensitivity (control systems) , x ray , physics , optics , materials science , electronic engineering , engineering
Measurements are carried out to determine the relative photographic effect produced by electrons emanating from metallic screens on a typical radiographic film. The electrons are produced in metal foils of aluminum, copper, and lead by the interaction of photons in a 400‐kV bremsstrahlung beam. Intensification factors of up to 1.65, 2.05, and 5.90 for aluminum, copper, and lead screens, respectively, are determined as a function of the foil thickness. The equilibrium thickness screens are determined to be 20 mg/cm 2 for aluminum and 30 mg/cm 2 for copper and lead. These results are compared with the absorbed dose in the film emulsions, calculated by Monte Carlo methods. The results of the present work are compared with those for 60 Co and 137 Cs photon beams. The dependence of the equilibrium thickness and the intensification factor on photon energy and the atomic number of the screen material is summarized and explained.