Ultrahigh speed imaging assembly for radiography

A radiographic imaging assembly having a system speed of at least 1100 and comprising:

• A) a symmetric radiographic silver halide film having a film speed of at least 800 and comprising a support that has first and second major surfaces,
• said radiographic silver halide film having disposed on said first major support surface, two or more hydrophilic colloid layers including first and second silver halide emulsion layers, and having on said second major support surface, two or more hydrophilic colloid layers including third and fourth silver halide emulsion layers, said first and third silver halide emulsion layers being the outermost emulsion layers on their respective sides of said support,
• each of said first, second, third, and fourth silver halide emulsion layers comprising tabular silver halide grains that have the same composition, independently an aspect ratio of from about 38 to about 45, an average diameter of at least 3.5 μm, and an average thickness of from about 0.08 to about 0.14 μm, and comprise at least 95 mol % bromide and up to 0.1 mol % iodide, both based on total silver in said grains,
• each of said second and fourth silver halide emulsion layers comprising a particulate oxonol dye as a crossover control agent present in an amount of from about 1 to about 1.3 mg/m2 that is sufficient to reduce crossover to less than 12% and that is decolorized during development within 45 seconds,
• said film further comprising a protective overcoat on both sides of said support disposed over all of said silver halide emulsion layers,
• wherein said tabular silver halide grains in said first, second, third, and fourth silver halide emulsion layers are dispersed in a hydrophilic polymeric vehicle mixture comprising from about 1 to about 15% of deionized oxidized gelatin, based on the total dry weight of said polymeric vehicle mixture,
• wherein the dry, unprocessed thickness ratio of said first silver halide emulsion layer to that of said second silver halide emulsion layer is from about 3:1 to about 1:1, and the dry, unprocessed thickness ratio of said third silver halide emulsion layer to that of said fourth silver halide emulsion layer is independently from about 3:1 to about 1:1, and
• wherein the molar ratio of silver in said first silver halide emulsion layer to that of said second silver halide emulsion layer is from about 1.5:1 to about 3:1, and the molar ratio of silver in said third silver halide emulsion layer to that of said fourth silver halide emulsion layer is independently from about 1.5:1 to about 3:1, and
• B) a fluorescent intensifying screen arranged on both sides of said film, the pair of screens having a screen speed of at least 600 and said screens having an average screen sharpness measurement (SSM) value that is at least 1.1 that of reference Curve A of FIG. 4 at a given spatial frequency, and each screen comprising a terbium activated gadolinium oxysulfide phosphor capable of absorbing X-rays and emitting electromagnetic radiation having a wavelength greater than 300 nm, said phosphor being coated in admixture with a polymeric binder in a phosphor layer on a flexible polymeric support.