Eastman-kodak Company

Robert V Brady

James R Buntaine

William E Moore

Luther C Roberts

The invention is generally accomplished by providing a tabular silver halide emulsion formation process in which the pH is controlled to greater than 9 by the addition of an alkali base prior to digesting to form uniform nucleated silver bromide particles. In a particularly preferred process the emulsion is adjusted to a pH greater than 9 by the use of sodium hydroxide, digestion takes place in between 3 and 7 minutes, and the emulsion making is completed in less than 100 minutes without the use of ammonium hydroxide. The emulsions formed are suitable for x-ray films and produce the image tone required by radiologists.

Formation of tabular silver halide emulsions utilizing high pH digestion

A unitary intensifying screen and radiographic element are disclosed comprised of adjacently coated silver halide emulsion and X radiation absorbing fluorescent layers. The fluorescent layer (a) is capable of attenuating at least 5 percent of a reference X radiation exposure produced by a Mo target tube operated at 28 kVp with a three phase power supply, wherein the reference X radiation exposure passes through 0.03 mm of Mo and 4.5 cm of poly(methyl methacrylate) to reach the fluorescent layer mounted 25 cm from a Mo anode of the target tube and attenuation is measured 50 cm beyond the fluorescent layer, (b) contains a phosphor which exhibits a conversion efficiency at least equal to that of calcium tungstate, (c) exhibits modulation transfer factors greater than those of reference curve A in FIG. 3, and (d) exhibits an optical density of less than 1.0. The emulsion and fluorescent layers are contiguously coated or optically coupled through a transmission medium transparent to latent image forming radiation and having a refractive index of at least 1.33, and the silver halide emulsion layer contains an agent for promoting the oxidation of silver atoms to silver ions to offset the effects of background radiation.

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Rochester, NY, United States of America

Robert V Brady