2 Radiographic FilmDiagnostic radiographic film is manufactured by coating both sides of a base material with an emulsion containing photosensitive crystals.Several other materials are also used to improve the performance and permanence of the film:BaseAdhesiveEmulsion with crystalsSupercoat
3 Film Base Originally composed of a glass plate. Cellulose nitrate once used but extremely flammable.Nonflammable cellulose triacetate introduced in 1920s.Modern plastic bases (polyester introduced by DuPont in the 1960’s) solve problems such as cut fingers from broken films and strained backs from carrying and filing stacks of heavy radiographs.
4 Film Base Flexible yet tough Stable Rigid Uniformly lucent Permit easy handling in the darkroom.Make good contact with cassette pressure pads.StableDoes not change its dimension during the heating and immersion in chemicals required for processing.RigidTo be placed onto viewbox.Uniformly lucentPermits transmission of light without adding artifacts to the diagnostic image.
5 ReflectionsCrossover effect: blurring of the image caused by light from one screen crossing into the light from another screen.Halation: an effect on a radiographic image caused when light that is reflected from the air interfaces on the back of the base material.Antihalation coating: a substance applied to the back of a single-emulsion film designed to absorb light coming from the emulsion and preventing backscatter, (removed by the processing chemicals to permit light to be transmitted through the film for viewing).
6 AdhesiveDesigned to glue the emulsion to the base and prevent bubbles or other distortion when the film is bent during processing or handling, or when it is wet and heated during development.
7 EmulsionComposed of gelatin in which photosensitive silver halide crystals are suspended.Acts as a nonreactive, neutral lucent suspension medium for the silver halide crystals (silver bromide, silver iodide, and silver chloride) that must be separated from one another to permit processing chemicals to reach them.Distributes the crystals evenly over the surface of the film- preventing clumps that would make one area of the film more photosensitive than another.
8 SupercoatLayer of hard protective gelatin designed to prevent the soft emulsion from being abused physically or chemically.
9 Manufacturing Radiographic film is manufactured in four stages: Crystal productionRipeningMixingCoating
10 Crystal Production AgNO3 + KBr AgBr + KNO3 Gelatin must be present: A medium to permit the crystals to formLimit oxidation and reduce crystal surface tensionFacilitate other reactionsConventional grainTabular grain:Larger more evenly dispersedAbsorption of a greater portion of the exposing photonsReduced light crossover from one emulsion to the otherReduced silver coating requirements
11 Crystal StructureStructure permits both free silver atoms and free electrons to drift through the lattice- key to the formation of the latent image.Negatively charged surfacesPositively charged exteriorsSensitivity speck: must be present to provide film sensitivityServe as electrodes to attract the free silver ionsBromide: serve as ion pumps to assist in the deposition of silver.
12 Ripening Period during which silver halides are allowed to grow Size of the crystal determines their total sensitivity.At the proper time, emulsion is cooled, shredded, and washed to remove KNO3 (potassium nitrate)
13 MixingColored dyes: improve the sensitivity of the silver halides to match the wavelengths of photons that will be striking the emulsions during exposure.Panchromatic: sensitive to al colorsOrthochromatic: not sensitive to the red spectrumHardeners: to prevent physical traumaBactericides and fungicidesAntifogging agents: to decrease sensitivity to environmental factors, such as heat.
14 Latent image formation The latent image is the unseen change in the atomic structure of the crystal lattice that results in the production of a visible image.
16 Types Of Film Direct Exposure/ nonscreen films Intensifying screen filmsSpecial Application FilmsMammographyDetail extremity radiographyContact surgical radiographyCathode Ray Tube (CRT) imagingLaser FilmsDuplication FilmsFluoroscopic spot filming
17 Direct Exposure/ Nonscreen films Used primarily for industrial nondestructive testing (NDT) radiography.When extremely fine detail is critical to the diagnostic quality of the image (extremely high radiation exposure).DentalReconstructive surgery of the handsBiopsy specimenForensicsSingle emulsion, extremely fine grain silver halide crystals, much greater silver content.Thicker emulsion layer to achieve sufficient sensitivity- requires manual processing.
18 Intensifying Screen Films Wide variety of speeds (controlled by the size of the crystals and the thickness of the emulsion), contrast ranges, latitudes, and resolutions.Larger crystals and thicker emulsions usually provide lower contrast, wider latitude, and less resolution.Double emulsion
19 Special Application Films Fine grain films sensitive to a single screen:Mammography: x-ray examination of the breastDetail extremity radiography: imaging that uses slower speed filmsContact surgical radiography: nonscreen film in sterilized packagesCathode Ray Tube (CRT) imaging Video imaging): requires a film that is sensitive to the light emitted by the CRT
20 Special Application Films Lasers films: directly exposed by the laser used in the imaging cameraFilm must be sensitive to the frequency of light emitted by the particular camera.Produces near distortion free imagesDuplication film: designed to provide an exact image of the original film.Single emulsionChemically fogged to D-Max – further exposure decreases optical density (OD).Fluoroscopic spot filming: imaging that is done with 70 mm roll film or 105 mm film chips that are sensitive to green light.
21 Film Storage and Handling Film should be stored at a temperature of 68* F or lower at all times.Films must be brought to room temperature in advance of use.Humidity must be maintained between 30 and 60 percent.Photosensitive materials must be protected from unfiltered light.Lead lining of storage area.Film should be stored on end.
22 Film IdentificationShould be permanently identified with medical record information.Date of exposureFull name of patientInstitution exposure madeReferring physicianPatient identification numberExamination ordered
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