RAD 354 Chapt 11 Radiographic Film/Receptor Image forming rays: remnant beam/exit radiation – scattered radiation (partially absorbed/attenuated) and non-interacting

X-ray beam

RAD Film – 2 main parts: emulsion and base Base: rigid, non-shrinking base to support the emulsion – now made of plyester Emulsion: Silver halide and gelatin. 98% is silver bromide, the rest is usually silver iodide

Latent Image Produced when the exit beam (remnant beam) exists the patient and interacts with the emulsion/image receptor Takes place at the sensitivity spec (center) due to liberated charges traveling in the development center (spec or receptor)

Film/Receptor Types Digital – – Computed Radiography (CR) = Photostimulable Phosphor (PSP) – Direct Radiography (DR/DDR) = Solid State X-ray Detector (SSXD) – Film: Screen, Direct Exposure, Mammo, Laser, Duplication, Spot Film, Subtraction and Cine

Direct Exposure Non-screen film – sensitive to x-rays – Like “bite wings” at the dentist

Screen Film – sensitive to both light and radiation Comes in a variety of contrast, latitude, spee and light color sensitivity – Larger silver halide crystals = faster speed and LESS DETAIL – Thick emulsion layer = faster speed and LESS DETAIL – Double emulsion layer – faster speed – prone to “CROSSOVER”

COLOR SENSITIVITY Spectral matching = matching the color spectrum of light given off by screens to that of the emulsion – Calcium Tungstate Crystals (atomic #’s 60/70’s) – Rare Earth – AMU’s mainly in the 50’s (57-71) – Orthochromatic = green sensitive film – Panchromatic = sensitive to all color (photographic film) – Laser = sensitive to red light

Other type films Mammo/routine films = some mammo is single emulsion and single screen film and some double/double Duplicating film – single emulsion, solaraized film Cine = Dynamic motion (heart caths, etc.) 35mm Spot film camera film = 70mm, 105mm

Darkroom Safelights Filter is spectral matched to filter out the light spectrum the film is SENSITIVE to (wratten 6-B = red safelight filter) Usually 15 watt bulb Should be no closer than 5 feet from work surface (some “feed trays” have a safelight that turns on after the film has progressed into the processor and out when a film begins to enter the processor)

Film Storage Boxes to be stored on end – NEVER flat! 68F (20C) best at 50F (1-C) AND low humidity (40% or LESS) Unexposed film is MUCH less sensitive to light, radiation, chemicals, heat, etc., than EXPOSED FILM! Shelf life – limited (film begins to develop as soon as it is made)

RAD 354 Chapt. 12 Processing the LATENT Image Basics / Dates: – Universal time and temp: 5 68 F – Each MAJOR step is 2X longer than the previous (manual processing) 1942 = First “Automatic Processor by Pako (some 20 ft. long and required film to be placed on “hanger racks” for transport) 1956 – First “ROLLER” transport processor by Kodak (5 minute)

Basics/dates, con’t = First 90 sec. processor by Kodak 1987 = First 45/90 sec variable processor by Konica Development = conversion of latent image to manifest image (black metallic silver) Fixation – Removes the UNEXPOSED and Undeveloped silver halide crystals – PRESERVES the MANIFEST (visible) image

90 Sec. Processor Items of Importance Time for devel and fix = 22 seconds for EACH Developing/Reducing agents: Hydroquinone, phenidone/ metol/ elan Fixing agents: Acetic acid, ammonium thiosulfate

Developing Agents Hydroquinone – SLOW acting build up of “blackest blacks” (also know as the reducing agent) Phenidone/metol/elan = act RAPIDLY to build up GRAYS “Buffering agents” (to maintain alkalinity) = sodium carbonate/sodium hydroxide (Lye) Restrainer = “Potass”ium bromide/iodide = prevents UNEXPOSED silver halide conversion to black metallic silver

Developer Con’t. Preservative = sodium sulfite Hardener = Gluteraldehyde/potassium alum/aluminum chloride/chrome alum

Fixing Agents Same hardener and preservatives as devel. Acetic acid = “activator “- STOPS action of developer Ammonium thiosulfate – FIXING AGENT Acetate – “Buffering agent” – helps maintain acidic pH

Washing Universal solvent = WATER “Hypo retention” = residual fixing chemicals on the film – Will turn the film brown over time – MUST BE CHECKED FOR MAMMO!!!

Automatic Processing Six total SYSTEMS Transport Temperature Circulation Replenishment Dryer Electrical

Transport Rollers and transport “racks,” drive gears – TRANSPORT ROLLERS are 1” in diameter (3.14” circum.) “Pi lines” are a common artifact – “Guide shoes” also can cause artifacts (especially with NEW processors and racks/cross over assemblies – Cross over rollers/racks – Time guidelines (time spent in devel/fixer) = +/- 2% of required time (22 sec. each in a 90 processor for fix and devel)

5 “Other” systems Temperature = proper temps for developer (95F), wash and dryer (110F) Circulation = agitates chemicals, FILTERS DEVELOPER Replenishment = meters and replaces chemistry (MICROSWITCH on feed tray) Dryer = Dries film (know diff. between “wet” and “tacky” Electrical = All electrical areas

Other/Special Processing Daylight = Enables one to place a cassette/receptor in the daylight processor and the processor opens/processes/reloads cassette/receptor Dry Porcessing: – Photothermic – Used laser to form a latent image and HEAT to make it visible – Thermographic – Uses heat to DIRECTLY produce the image