ISO 18939:2013 イメージング材料  —  医用画像用のデジタルハードコピー  —  永続性を測定する方法 | ページ 6

3.1

adherography

imaging technology utilizing a high intensity laser beam to form a positive carbon image through differential thermal adhesion

Note 1 to entry: This process involves fusion of a laser sensitive, carbon-containing layer with the final imaging layer in exposed areas, followed by controlled peeling, which removes the unexposed portion. The positive image is then made durable and permanent by the application of a transfer coat.

3.2

microcapsule

imaging technology in which heat-responsive microcapsules containing dye precursors are thermally rendered to develop a dye image

Note 1 to entry: Heat-responsive microcapsules containing dye precursors are dispersed together with a development emulsion on a polyester support. Application of computer-modulated heat that matches the density pattern of a digital image renders the walls of the microcapsules differently permeable. The varying amounts of developer, which penetrate the capsule walls, produce corresponding differences in dye image density. The capsule walls revert to their impermeable state on cooling and provide protection against dye formation and dye degradation under normal storage conditions.

3.3

phase change solid inkjet

imaging technology based on modulated deposition of micro-droplets of non-aqueous, waxy inks on a microcellular surface of a layer coated on a polyester support

Note 1 to entry: Four shades of neutral ink are used to obtain the wide grey scale density range required for medical images. The melting point of the ink is considerably above ambient temperature, ensuring image stability under normal storage conditions.

3.4

photothermography

imaging technology based on thermal development of a light-induced latent image in dispersed silver salts

Note 1 to entry: The process involves a polymeric layer containing light sensitive silver halide crystals, light insensitive silver behenate crystallites, silver soaps and a reducing agent coated on a polyester support. A latent image formed by light exposure of the silver halide crystals catalyses an oxidation-reduction reaction between the silver behenate and the reducing agent upon heating above 120 °C. This yields a metallic silver image by physical development.

3.5

thermography

imaging technology based on image-wise thermal modulation and development of dispersed silver salts

Note 1 to entry: The process utilizes a polymeric layer containing a light-insensitive organic silver salt, a reducing agent and a stabilizer, coated on a polyester support. Reduction of the organic silver salt by the reducing agent accelerated by heat (100 °C–200 °C) yields a metallic silver image whose densities are controlled by the adjustable temperature of print head elements. The integrity of the silver image under normal storage conditions is secured by stabilization of the unused silver salt.

3.6

aqueous inkjet

imaging technology involving image formation with an aqueous ink by a modulated deposition of micro-droplets on the surface of an ink absorbing layer coated on a polyester support

Note 1 to entry: Black-and-white and colour images can be produced by suitable selection of inks.

3.7

just noticeable difference levels

jnd-levels

measure of the non-linear response of the visual system to luminance stimuli defined as a table of ascending photometric luminance levels (between 1 and 10 000 cd/m²), which are perceived as equidistant with the smallest perceivable difference (“just noticeable difference”) between them^[20]

3.8

jnd-contrast

Δjnd

numerical difference between the jnd-levels of two neutral patches on a radiographic film for a given viewing situation (intensity of light box and ambient light intensity), which is used as measure of perceived contrast between the two patches

3.9

change in jnd-contrast

(Δjnd (t)/Δjnd(0)) – 1

measure of relative change in perceived contrast between two neutral patches — for example in the course of a stability test: Δjnd(t) / Δjnd(0) – 1, i.e. [(jnd-contrast after treatment)/(jnd-contrast before treatment)] – 1

3.10

colour changes

Δa*, Δb*

differences in the CIE colour coordinates a* and b*, e.g. in the course of incubation of dry hardcopy film

3.11

endpoints

set of numerical values defining those changes in colour (Δa*, Δb*) and jnd-contrast [(Δjnd(t)/Δjnd(0)) – 1] , for given reference visual density (D_vis) at which time to failure is evaluated in the course of thermal-stability and light-stability tests in order to produce Arrhenius extrapolation plots following the Arrhenius test method described in ISO 18924

3.12

diagnostic endpoint

set of endpoints, for which changes in colour (Δa*, Δb*) and jnd-contrast [(Δjnd(t)/Δjnd(0)) – 1] for given visual density (D_vis), have been correlated with loss of the materials’ diagnostic function based on statistically validated psychophysical scoring by radiologists

Note 1 to entry: At the time of writing this standard document insufficient data was available to specify diagnostic end points that could be judged as “relevant or prohibitive” from the standpoint of medical diagnostics. Diagnostic end points need a correlation with judgments or scores by radiologists, for which a statistically relevant set of psychometric data for a given medical application or modality is needed. Diagnostic end points depend on a variety of factors, amongst which are — nonexclusively — type of modality, pathology under investigation, method of image processing, printer settings and density range of the medical image.

3.13

illustrative endpoints

set of arbitrarily defined endpoints for changes in colour (Δa*, Δb*), and jnd-contrast Δjnd(t)/Δjnd(0) – 1 for a given reference visual density D_vis, at which time to failure is evaluated in the course of thermal stability tests

Note 1 to entry: Arrhenius extrapolations based on illustrative end points do not have any proven diagnostic or clinical relevance due to the lack of corresponding psycho-visual data. For diagnostically relevant Arrhenius extrapolations a set of diagnostic end points would be necessary.

3.14

film base

plastic support for the emulsion and backing layers

3.15

emulsion layer

image or image-forming layer of photographic films, papers and plates

3.16

safety poly (ethylene terephthalate) base

polyester film base composed mainly of a polymer of ethylene glycol and terephthalic acid

3.17

processed dry hard copy film

dry hard copy film on which a (test) image has been written by its corresponding printer (in analogy to the wet processing of conventional AgX based film)