1
Q
Film Processing
A
Converts latent image to manifest image Two basic methods used: Manual and Automatic
2
Q
Manual Processing Steps
A
Wetting Agent – (optional) Developer – most important processing step Stop Bath or Water Rinse Fixer Washing – prevents hyporetention Drying
3
Q
Processing Chemistry Developer
A
Most important processing step Converts latent image to manifest image Uses oxidation/reduction reaction or redox
4
Q
Developer Chemicals
A
Component: Developing agents, Buffer, Restrainer, Preservative, Hardener, Sequestering agent, Solvent
5
Q
Accelerator, Activator, or Buffering Agents
A
- Maintain alkaline (high-pH) medium - Soften and swell film emulsion - Chemicals used can be either sodium carbonate, sodium hydroxide, potassium carbonate, or potassium hydroxide
6
Q
Restrainer, Regulator, Antifoggant, or Starter
A
- Restrains the action of developing agents to help prevent chemical fog - Chemicals used can be either potassium bromide or potassium iodide
7
Q
Hardener
A
- Keeps the film emulsion from sticking to rollers in processor - Weaker hardener than is found in fixer solution - Chemical agent is glutaraldehyde
8
Q
Solvent
A
- Other components are mixed with solvent to create developer solution - Agent used is water (should be drinkable in quality)
9
Q
Sequestering Agent
A
- Used for developer solutions that are mixed from concentrate - Keeps impurities found in tap water from oxidizing reducing agents - Chemical agent is ethylenediamine tetraacetic acid (EDTA)
10
Q
Developer Solution Options
A
- Ready or Pre-mix – easier but more expensive - Concentrate – cheaper but less convenient - Three-part kit is mixed with water - Must be mixed properly
11
Q
Processing Chemistry Fixer
A
- Removes unexposed and undeveloped silver halide crystals - Stops development process - Permanently hardens film emulsion for archival storage
12
Q
Fixer Components: Fixing agent, Clearing agent
A
Removes unexposed and undeveloped silver halide crystals (film clearing)
13
Q
Preservative
A
- Helps recycle fixing agent - Chemical agent is sodium sulfite - Level should be maintained in range of 15 to 50 g/L
14
Q
Hardener or Tanning Agent
A
- Permanently hardens film emulsion for long-term archival storage - Hardening process is also called tanning - Chemical agents can be potassium alum, chrome alum, or aluminum chloride
15
Q
Acidifier, Activator, or Buffer
A
- Neutralizes any developer remaining in film emulsion - Maintains acid (low-pH) medium for fixing agent - Chemical agent can be either acetic or sulfuric acid
16
Q
Sequestering Agent
A
Helps prevent development of aluminum hydroxide (alkaline compound)
17
Q
Solvent
A
- Other components are mixed with solvent to create fixer solution - Agent used is water (should be drinkable in quality) - Specific gravity should be between 1.077 and 1.11 to ensure proper concentration
18
Q
Fixer Solution Options
A
- Ready or Pre-mix – easier but more expensive - Concentrate – cheaper but less convenient - Two-part kit is mixed with water - Must be mixed properly
19
Q
Washing Step
A
- Removes excessive fixer to prevent hyporetention - Hyporetention can cause white, powdery residue (short term) and brown stain (long term) - Hyporetention degrades archival quality of film images
20
Q
Developer Activity Factors
A
- Solution Temperature - Immersion Time - Solution Concentration - Type of Chemicals - Solution pH - Exhaustion/Replenishment
21
Q
Processing Time
A
- Developer immersion time should be maintained to within ± 2% to 3% of manufacturer’s specification - Can be checked with time-in-solution test tool and a stopwatch
22
Q
Replenishment Rate
A
- Values indicated on flow meters should be within ± 5% of manufacturer’s specification - If no flow meters are present, can be checked by catching solution in graduated cylinder and measured
23
Q
Developer or Reducing Agents
A
- Phenidone – fast acting, producing optical densities under 1.2 - Hydroquinone – slow acting, producing optical densities above 1.2 - Uses Synergism or Superadditivity
24
Q
Solution temperature
A
- Developer temperature should not vary by more than ± 0.5° F (0.3° C) from manufacturer’s specification - Fixer temperature should be maintained within ± 5° F (3° C) of developer temperature - Wash water should be either the same or about 5 degrees colder than fixer temperature
25
Solution pH
- Developer pH should be maintained between 10 and 11.5 - Fixer pH should be maintained between 4 and 4.5 - Can be checked by using either test paper or a pH meter
26
Specific Gravity and Proper Mixing
- Developer should be maintained between 1.07 and 1.1 - Fixer should be maintained between 1.077 and 1.11 - Can be checked with a hydrometer
27
Hyporetention Test
- Also called fixer retention test - Should be performed at least every 6 months - Drop of test solution is placed on film and degree of brown stain formed is analyzed - ANSI standards are 2 μg/cm2 for radiographic film and 5 μg/cm2 for mammographic films
28
OSHA Hazard Communication Standards
- Employees must be aware of potential hazards from processing chemicals - Materials Safety Data Sheets (MSDS) used for this purpose - Must be posted for all employees to see
29
OSHA Personal Protective Equipment (PPE) standards
- Designed to protect employees from workplace hazards - Mandate that protective eyewear, rubber gloves, and gowns be provided when mixing or transferring chemicals
30
Environmental Protection Agency (EPA)
- Requires users of developer solution to report quantity used - Limits amount of silver that can be discharged into municipal sewer systems (no more than 5 mg/L) - Requires special permit for transporting silver laden or cartridges
31
Chemical Safety
- Developer solution is the most hazardous of processing solutions - Developer is dangerous to eyes and a slight hazard to skin - Fixer is dangerous to eyes and can be respiratory and skin irritant
32
Automatic Processor Main Systems
- Transport System - largest and most complex system - Made up of many moving parts, so is most likely to break down - Consists of three subsystems: - Roller subsystem - Transport-rack subsystem - Drive subsystem
33
Transport System – Roller Subsystem
- Entrance rollers – found on entrance rack - Transport or planetary rollers – most numerous - Master or solar rollers – largest
34
Transport System – Transport-rack Subsystem
- Entrance rack - Vertical or deep racks - Turnaround racks - Crossover racks – must be cleaned before use daily, since they sit above liquid levels
35
Temperature Control System
- Regulates solution temperature - Water-controlled system – uses temperature of wash water to regulate solution temperatures - Thermostatically controlled – most common - Consists of heating coils that are thermostatically controlled - Requires only cold water input into processor
36
Circulation System
- Also known as recirculation and filtration system - Ensures complete chemistry mixing - Provides uniform temperatures - Provides equivalent of agitation performed in manual processing
37
Replenishment System
- Also known as regeneration system - Used to replenish developer and fixer solutions - Consists of pumps, storage tanks, and plastic tubing - Developer should maintain a bromide level of between 4 g/L and 8 g/L - Fixer should maintain a dissolved silver content of between 4 g/L and 8 g/L
38
Replenishment System (Cont.)
Available in two options: - Volume replenishment – replenishes each time a film enters processor - Flood replenishment – replenishment pumps are controlled by a timer - Both methods replenish more fixer than developer
39
Dryer System
- Consists of 2 to 3 heating units of between 1500 and 2500 watts - These use between 60% and 80% of all electrical power in processor - Air is blown through a series of air tubes to increase velocity of air - Combination of high-temperature (120° to 150° F) and high-velocity (100 to 300 ft3/min) dry film
40
Electrical System
- Distributes electrical power and monitors operation of the other systems - Usually consists of a solid state microprocessor circuit - Some models can actually perform many Quality Control functions
41
Types of Automatic Processors
7 minute 3 minute 90 second 60 second 45 second Multispeed – transport system speed can be varied to select different combinations of the above
42
Processor Size
- Floor Size – largest size, used for high-volume processing conditions - Intermediate Size – in-between size often found in smaller clinics and physician offices - Table or Countertop Size – smallest size, used in small darkrooms and mobile trailers
43
Processor Location Options
- Totally inside darkroom - Bulk inside darkroom - Bulk outside darkroom - Totally outside darkroom – most often called a daylight system
44
Processor Quality Control
Daily - Clean cross-over racks - Check developer temp - Check wash-water temp - Check replenishment rates - Sensitometry and densitometry
45
Processor Quality Control (Cont.)
Weekly - Clean entire rack assembly and processing tanks - Visual check of belts, pulleys, and gears - Lubrication (weekly or monthly)
46
Justification for Silver Recovery
- Worldwide Supply of Silver, Less silver being mined due to low prices and high refining costs - Monetary Return to Department - Federal and State Pollution Laws - Water Control Act of 1972 - Resource Conservation/Hazardous Waste Act of 1976 - Clean Water Act of 1984 - Resource Conservation and Recovery Act of 1987
47
Metallic Replacement
- Also known as displacement method - Consists of plastic bucket containing iron cartridges inside - Cartridges can be either steel wool or iron impregnated foam
48
Steel Wool Cartridges
- Most common type of cartridge - Subject to the following problems: - Channeling - Rusting - Drain Stoppage
49
Iron-impregnated Foam Cartridge
- Consists of powdered iron impregnated in plastic foam - Minimizes channeling and rusting - Provides 50% more surface area than steel wool for greater efficiency
50
Direct Sale of Used Fixer
- Used fixer is collected instead of going down drain - No equipment required and no chemical discharge into drain - Requires pick-up, handling, and/or storage fee
51
Chemical Precipitation
- Oldest form of silver recovery - Chemicals are added to used fixer that cause silver to sink to bottom of tank - Performed by silver refiners and not healthcare facilities
52
Ion Exchange or Resin Systems
- Uses negatively charged resin to attract positive silver ions - Regeneration cycle is used to release silver from resin - Similar in principle to water softener
53
Silver Recovery from Film
- 50% of silver is dissolved in fixer and removed by previous methods - 50% of silver remains on film - Film that is not diagnostic or no longer needed can be sold to silver dealer for silver recovery
54
Green Film
- Film that has not been processed - Most valuable type of film for recovery - Up to 0.4 troy ounce of silver per sheet of 14” x 17” film is available for recovery
55
Scrap Exposed Film
- Film that has been exposed and processed but not diagnostically useful - Examples include rejects, old sensitometry films, and film images of patients that have been scanned into digital archive - Average of 0.11 troy ounce of silver per 14” x 17” sheet of film available
56
Archival Film
- Has been exposed and processed but dates prior to 1974 - Film had about 20% more silver than film made since that time - About 0.13 to 0.18 troy ounce of silver available per sheet of 14” x 17” film available for recovery
57
Silver Recovery Systems
- Feasible from financial standpoint - Prevents toxic heavy metal pollution in environment
58
Must adhere to legislative acts:
- Water Control Act of 1972 - Hazardous Waste Act of 1976 - Clean Water Act of 1984 - Conservation and Recovery Act of 1986
59
Processor Cleaning Procedures
Daily: - Rinse crossover racks - Rinse deep racks - Observe transport system during operation - Observe solution level in tanks - Rinse and remove crossover racks at shutdown
60
Processor Cleaning Procedures (Cont.)
Monthly: - Drain and wash all processing tanks - Rinse with water and refill with fresh solution - Add starter solution to developer to get bromide level to operating level
61
Processor Cleaning Procedures (Cont. 2)
Quarterly: - Drain, wash, and rinse all replenishment tanks - Refill tanks with fresh solution and check specific gravity with hydrometer
62
Processor Cleaning Procedures (Cont. 3)
Yearly: - Remove all racks and rollers and clean thoroughly - Use a systems cleaner for some models
63
Processor Maintenance
Scheduled Maintenance Preventive Maintenance Nonscheduled Maintenance
64
Processor Monitoring
Sensitometric Testing Requires the following: - Sensitometer – creates step pattern on film - Densitometer – measures optical density of step from sensitometer image
65
Sensitometry Film Performance Indicators
- Base + fog (B + F) – should not vary by more than ± 0.05 for dual emulsion and 0.03 for single emulsion films - Speed or mid-density (MD) indicator – optical density of step closest to 1.0 above B + F and should not vary by more than ± 0.15 from accepted value
66
Quality Control Film
- Film used in sensitometric testing should be kept in separate box - New box will cause accepted values of performance indicators to change
67
Daylight Systems
- Require same cleaning, maintenance, and monitoring as standard film processors - Film transport mechanisms require extra maintenance to keep films from jamming within the system
RADT 110
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