Asymmetrical radiographic elements, assemblies and packages

Claim 2

A radiographic element comprised of a transparent film support, first and second silver halide emulsion layer units coated on opposite sides of the film support, and means for reducing to less than 10 percent crossover of electromagnetic radiation of wavelengths longer than 300 nm capable of forming a latent image in the silver halide emulsion layer units, said crossover reducing means being decolorized in less than 90 seconds during processing of said emulsion layer units, characterized in that said first and second silver halide emulsion layer units exhibit significantly different sensitometric characteristics and means are provided for ascertaining which of said first and second emulsion layer units are positioned nearest a source of X-radiation during exposure.

Claim 3

A radiographic element according to claim 1 further characterized in that said first silver halide emulsion layer unit exhibits a speed at 1.0 above minimum density which is at least twice that of the second silver halide emulsion layer unit, the speed of the first silver halide emulsion layer unit being determined with the first silver halide emulsion unit replacing the second silver halide emulsion unit to provide an arrangement with the first silver halide emulsion unit present on both sides of the transparent support and the speed of the second silver halide emulsion layer unit being determined with the second silver halide emulsion unit replacing the first silver halide emulsion unit to provide an arrangement with the second silver halide emulsion unit present on both sides of the transparent support.

Claim 4

A radiographic element according to claim 2 further characterized in that the first silver halide emulsion layer unit is from 2 to 10 times faster than the second silver halide emulsion layer unit.

Claim 5

A radiographic element according to claim 3 further characterized in that the first silver halide emulsion layer unit is from 2 to 4 times faster than the second silver halide emulsion layer unit.

Claim 6

A radiographic element according to claim 1 further characterized in that said first silver halide emulsion layer unit exhibits an average contrast of less than 2.0, based on density measurements at 0.25 and 2.0 above minimum density and said second silver halide emulsion layer unit exhibits an average contrast of at least 2.5, based on density measurements at 0.25 and 2.0 above minimum density, the contrast of the first silver halide emulsion layer unit being determined with the first silver halide emulsion unit replacing the second silver halide emulsion unit to provide an arrangement with the first silver halide emulsion unit present on both sides of the transparent support and the contrast of the second silver halide emulsion layer unit being determined with the second silver halide emulsion unit replacing the first silver halide emulsion unit to provide an arrangement with the second silver halide emulsion layer unit present on both sides of the transparent support.

Claim 7

A radiographic element according to claim 5 further characterized in that the first silver halide emulsion layer unit exhibits an average contrast that differs by 0.5 to 3.5 from that of the second silver halide emulsion layer unit.

Claim 8

A radiographic element according to claim 6 further characterized in that the first silver halide emulsion layer unit exhibits an average contrast that differs by 1.0 to 2.5 from that of the second silver halide emulsion layer unit.

Claim 9

A radiographic element according to claim 1 further characterized in that the crossover reducing means decreases crossover to less than 5 percent.

Claim 10

A radiographic element according to claim 8 further characterized in that the crossover reducing means decreases crossover to less than 3 percent.

Claim 11

A radiographic element according to claim 1 further characterized in that the crossover reducing means is comprised of a hydrophilic colloid layer interposed between at least one of said silver halide emulsion layer units and said support containing a dye capable of absorbing electromagnetic radiation to which said silver halide emulsion layer unit on the opposite side of the support is responsive.

Claim 12

A radiographic element according to claim 10 further characterized in that the dye in said interposed layer is, prior to processing, in the form of particles and is capable of being decolorized during processing.

Claim 13

A radiographic element according to claim 1 further characterized in said silver halide emulsion layer unites are comprised of emulsions in which tabular silver halide grains having a thickness of less than 0.3 μm exhibit an average aspect ratio of greater than 5:1 and account for greater than 50 percent of the total grain projected area.

Claim 14

A radiographic element according to claim 12 further characterized in that said silver halide emulsion layer units are spectrally sensitized to at least 60 percent of their highest attainable sensitivities.

Claim 15

A radiographic element according to claim 13 further characterized in said silver halide emulsion layer units are comprised of emulsions in which tabular silver halide grains having a thickness of less than 0.2 μm exhibit an average aspect ratio of greater than 8:1 and account for greater than 70 percent of the total grain projected area.

Claim 16

A radiographic element according to claim 1 further characterized in that said emulsion layer units and crossover reducing means are each comprised of processing solution permeable hardenable hydrophilic colloid layers, said crossover reducing means includes a hydrophilic colloid layer interposed between one of said emulsion layer units and said support containing a particulate dye capable of absorbing radiation to which said emulsion layer unit coated on the opposite side of the support is responsive and at least 10 mg/dm 2 of said hardenable hydrophilic colloid, said emulsion layer units contain a combined silver coating coverage sufficient to produce a maximum density on processing the range of from 3 to 4, a total of from 35 to 65 mg/dm 2 of processing solution permeable hardenable hydrophilic colloid is coated on each of said opposed major surfaces of said support, and said processing solution permeable hydrophilic colloid layers are forehardened in an amount sufficient to reduce swelling of said layers to less than 300 percent, percent swelling being determined by (a) incubating said radiographic element at 38° C. for 3 days at 50 percent relative humidity, (b) measuring layer thickness, (c) immersing said radiographic element in distilled water at 21° C. for 3 minutes, and (d) determining the percent change in layer thickness as compared to the layer thickness measured in step (b), whereby said radiographic element exhibits high covering power, reduced crossover without emulsion desensitization, reduced wet pressure sensitivity, and can be developed, fixed, washed, and emerge dry to the touch in a 90 second 35° C. process cycle consisting of ______________________________________ development 24 seconds at 40° C., fixing 20 seconds at 40° C., washing 10 seconds at 40° C., and drying 20 seconds at 65° C., ______________________________________ where the remaining time is transport between processing steps, the development step employs the following developer: ______________________________________ Hydroquinone 30 g 1-Phenyl-3-pyrazolidone 1.5 g KOH 21 g NaHCO.sub.3 7.5 g K.sub.2 SO.sub.3 44.2 g Na.sub.2 S.sub.2 O.sub.5 12.6 g NaBr 35 g 5-Methylbenzotriazole 0.06 g Glutaraldehyde 4.9 g Water to 1 liter at pH 10.0, and ______________________________________ the fixing step employs the following fixing composition: ______________________________________ Ammonium thiosulfate, 60% 260.0 g Sodium bisulfite 180.0 g Boric acid 25.0 g Acetic acid 10.0 g Aluminum sulfate 8.0 g Water to 1 liter at pH 3.9 to 4.5. ______________________________________

Claim 17

A radiographic element according to claim 1 further characterized in that said means for ascertaining which of said first and second emulsion layer units are positioned nearest a source of X-radiation during exposure is comprised of a mark capable of being seen under safe-light conditions.

Claim 18

A radiographic element according to claim 1 further characterized in that said means for ascertaining which of said first and second emulsion layer units are positioned nearest a source of X-radiation during exposure is comprised of means for permitting tactile discrimination between said first and second emulsion layer units.

Claim 19

A radiographic element according to claim 17 further characterized in that said means for permitting tacile discrimination is a boundary rendering said support asymmetrical.

Claim 20

A radiographic element according to claim 18 further characterized in that said support is rendered asymmetrical by an aperture or edge notch.

Claim 21

An imaging assembly comprised of a radiographic element and a front and back pair of intensifying screens characterized in that said radiographic element is that recited in any one of claims 1 to 19 inclusive.

Claim 22

An imaging assembly according to claim 20 further characterized in that at least one of said front and back intensifying screens includes means for referencing its orientation to that of said radiographic element.

Claim 23

An imaging assembly according to claim 21 further characterized in that said orientation referencing means is comprised of a visual indicator capable of being seen under safe-light conditions.

Claim 24

An imaging assembly according to claim 21 further characterized in that said radiographic element and said front and back intensifying screens each include means for permitting tactile identification of their orientation.

Claim 25

An imaging assembly according to claim 23 further characterized in that said means for permitting tactile identification of the orientation of said radiographic elements and said first and second screens is comprised of a boundary rendering each of said radiographic element and said first and second screens asymmetrical.

Claim 26

An imaging assembly according to claim 24 further characterized in that said radiographic element and said front and back screens are each rendered asymmetrical by an aperture or edge notch.

Claim 27

An exposure package comprised of an assembly and means forming a cassette housing for said assembly, characterized in that said assembly is constructed according to claim 20.

Claim 28

An exposure package according to claim 26 further characterized in that said assembly includes at least one boundary for imparting asymmetry and said cassette housing includes means for limiting said asymmetry imparting boundary to a single orientation.

Claim 29

An exposure package according to claim 27 further characterized in that said cassette housing includes means peripherally defining a seating area for said assembly and means for rendering said seating area asymmetrical.

Claim 30

An exposure package according to claim 28 further characterized in that said means for rendering said seating area asymmetrical includes a pin.

Claim 31

An exposure package according to claim 28 further characterized in that said means for rendering said seating area asymmetrical includes an edge for cooperating with an asymmetrical edge of said assembly.

Claim 32

An exposure package according to claim 26 further characterized in that an exposure step tablet is located on said cassette housing.