Intensifying effect of metallic screens on the sensitivity of x-ray films for 400-kV bremsstrahlung photons.
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 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/cm2 for aluminum and 30 mg/cm2 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 60Co and 137Cs 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.
Navon
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Center for Radiation Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20599.
Dick
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CE
Barnea
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D000535:Aluminum; D003300:Copper; D006801:Humans; D007854:Lead; D014962:X-Ray Film; D014963:X-Ray Intensifying Screens
D007854:Lead; D003300:Copper; D000535:Aluminum