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The Darkroom
Radiography for Veterinary Technicians
Question | Answer |
---|---|
Describe the function of the fixer. | to remove unchanged silver halide crystals from the emulsion layer on the film, thus stopping the developing process |
What is the function of the developer? | to convert sensitized silver halide crystals into black metallic silver |
List causes of artifacts associated with processors. | light leaks in the darkroom, temperature of chemicals not accurate, fixer mixing with developer, poor final wash, fixer used before developer |
Explain the darkroom requirements. | clean, lightproof, and free of chemical odor. It should also have a dry side and wet side. |
List the advantages and disadvantages of automatic processing. | minimizes human error. processes film in as a little as a minute and a half. They produce quality images & reduce the need for repeat radiographs due to processing errors- disadvantage- chemicals costly, expensive to repair |
Is the pH of the fixer chemical alkaline or acidic? | acidic |
What is the chemical compound that allows film to respond to light? | silver halide |
Most states have a requirement to trap elemental silver from which chemicals after processing? | fixative |
Silver halide crystals that remain on the film are removed during what stage? | fixer stage |
Direct safelights should be a minimum of how many feet from the work area? | 4 |
What is the correct wattage to use for a safelight bulb? | 7-10 watts |
Is the pH of the developer chemical alkaline or acidic? | strong alkaline |
What is the restraining agent used in developer? | potassium bromide |
A black tree pattern artifact on the film is usually caused by what? | static electricity during handling of the film |
A finished film's image is blurred. What is it most likely caused by? | Motion |
Where in the darkroom is there most likely to be a light leak? | around the door or the seams in a suspended ceiling |
Besides light proofing, what else should be taken into consideration for a darkroom? | ventilation and safelights |
What is meant by the wet side and the dry side of the dark room? Why is this important? | One area of the darkroom should house the wet materials. Another area should house the materials that aren’t supposed to get wet. If film gets wet before it’s ready to be placed into the developer, it will be damaged. |
What are the components of the developer? | developing agent, activator, restrainer, preservative, hardener, solvent |
What are the components of the fixer? | fixing agent, acidifier, preservative, hardener, solvent |
What are the steps in the manual processing procedure? | develop, wash, fix, wash, dry |
Explain the importance of washing and drying film. | if they are not washed, sulfiding or staining can result, rendering the films non-diagnostic. They should be completely dry to prevent scratching or fingerprints being left on the films |
Describe the advantages and disadvantages of manual processing? | less costly Disadvantage: closer contact with chemicals, more room for human error |
What temperature are the developer and fixer of an automatic processor commonly kept at? | 97 degrees |
Why is ventilation important? | Processing chemicals are unpredictable and should not be left to linger & accumulate- the fumes are dangerous to people and the film (can cause film fog) ventilation fans are are must |
What are safelights used for? | They are special lights used in the darkroom, so that people can see, without damaging the film (often look red). |
How often should chemicals be changed? | Every 6-8 weeks, regardless if they've been used or not |
What are the two chemicals used in processing of film? | the developer and the fixer |
Approximately how long does automatic processing take? | 90-120 seconds |