Darkrooms – Still Necessary? Darkrooms are necessary for manually fed processors and daylight processors. -Loading automatic film processor magazines. Necessary for conducting certain quality control tests (daily sensitometric strip).
DARKROOM FUNCTION # 2 Purpose of Film Processing Change silver halide crystals from film emulsion (after exposure to x-ray or light photons) to black metallic silver. Latent image (invisible until processed) is developed into a Manifest image. Improper or careless processing can cause poor diagnostic quality.
Processing Film Table top Processors TABLE TOP PROCESSOR Can process as fast as 60 seconds
PROCSSING CHEMICALS Solutions are PRE- MIXED Solutions are PRE- MIXED Outside Company usually provides service- Outside Company usually provides service- Weekly or monthly Weekly or monthly Solutions should be replenished as necessary & changed regularly Solutions should be replenished as necessary & changed regularly Solutions must be monitored (Daily QC strip). Solutions must be monitored (Daily QC strip).
Processor Chemistry Overview Developer – converts latent image into manifest image Fixer – clear the film of unexposed, undeveloped silver bromide crystals, promotes archival quality Wash – rid the film of residual chemicals
Developer Solution 3. Hardener: prevents damage to the film from over swelling of gelatin in automatic processors. -Gluteraldehyde 4. Preservative: Antioxidant that prevents oxidation of developer -Sodium Sulfite
Developer Solution 5. Restrainer: prevents chemical fog in new developer -Potassium Bromide 6. Solvent: dissolves & ionizes the developer chemicals -Water
Wash Rid the film of residual chemicals Residual chemicals on the film will discolor radiograph over time. Cold water processors are less efficient in removing chemicals – Warm water processors much better. Agitation during wash process is essential
Replenishment System Main function: Keep solution tanks full and assure proper solution concentration. As film is introduced into processor, sensor initiates solution replenishment Right & wrong way to feed in film -Feed in along short edge
Transport System in Automatic Processors Conveys the film through different solutions (sections) by a series of rollers driven by gears, chains & sprockets. Done at a prescribed speed – determines length of time the film is in each solution
Temperature Regulation Main function: To control the temperature of each section of the processor. Developer – most important solution to regulate Usually between 92 degrees and 95 degrees Thermostatically controlled
Recirculation System Provides agitation necessary for uniform solution concentration
Wash & Dryer Systems Wash: Provide thorough removal of chemical solutions from the film. -Archival film quality Dryer: Removes water from film by blowing warm, dry air - Between 120 degrees & 130 degrees F.
Silver Recovery About ½ of the film’s silver remains in the emulsion after exposure & processing. Other ½ (unexposed silver) is removed from the film during fixing process. Silver is toxic to public water supply – must have proper disposal. Silver can be harvested from the fixer tank and recycled.
Darkroom Contents Loading Bench Film Bin Film I.D. Printer Safelights Pass Box Light-tight Room Ample ventilation Warning Light outside room Lockable Door Wall Shielding if adjacent to x-ray room Walls painted with light color to reflect safelight