Film Processing Chapter 7. Film Processing Proper film processing is vital to the production of a quality radiograph. Processing can be done manually.

Film Processing

Chapter 7

Film Processing

Proper film processing is vital to the production of a quality radiograph.

Processing can be done manually or automatically.

The Darkroom

Three qualities of a good darkroom 1. Clean

2. Organized

3. Lightproof

Darkroom continued

Individual darkrooms may vary in design, but should all possess the same qualities.

Should be separate from the radiographic suite and should be used for only one purpose, processing exposed radiographs.

Darkrooms

Most of work in darkrooms is with minimal light (hence the word “Dark”).

Therefore layout should be such as to help reduce possibility of film damage.

Darkroom cleanliness

Should be clean as only room where intensifying screens and x-ray film is exposed to the air.

Should have proper climate control. Don’t want too humid. Why?

Darkroom Organization

Should be organized so that all equipment can be located quickly and easily.

Should be two sides to the darkroom a dry side and a wet side.

Dry Side of Darkroom

Where cassettes are unloaded and reloaded.

Should have countertop large enough to accommodate the largest cassette in an open position.

Countertop should be easy to clean. Nothing “wet” should be brought to

the dry side.

Dry side of Darkroom continued

Customary to store film under the dry table in a bin or cupboard. How should film be stored?

Film hangers for each size film should be hung above the table on the dry side.

Film Hangers Available in two designs:

Channel Hangers Tend to retain water and chemicals and need

special cleaning and drying to prevent contaminations of the dry side.

Film must be removed from the channel hangers in order to be dried.

Clip Hangers More fragile than channel hangers. Clips can become weakened over time. Lose ability to stretch the film. Can puncture the corners of the film. Can scratch other films.

Film Hangers

Wet Side of Darkroom

Where actual chemical processing occurs.

Hand or manual processing consists of three tanks. Developer Water Fixer

Manual processing tanks Can be individually free standing. Fixer and Developer can be placed in

one large tank filled with thermostatically controlled water.

One of most important pieces of equipment is thermometer when using manual processing. Processing chemicals must be certain

temperature.

Wet side/ Drying area

Film drying area can consist of a film drying rack or a drying cabinet.

Drying rack should be dust free. Drying cabinet is a heated forced-air

unit that hastens the drying process. Viewing screen is recommended on

wet side of darkroom.

Darkroom Lightproofing

Light leaks can cause film fog.

Light leaks

May be hard to perceive. Common sources of light leaks.

Entrance to dark room Ceiling From adjacent rooms

Lightproofing continued

Entrance should have double door or revolving door preferred but not always practical.

Make sure that door fits tightly into its frame. Use weather stripping if needed to

ensure light proofing. Make sure that door LOCKS!

Ceiling/walls/etc

Suspended ceiling may have light leaks from adjacent rooms.

Walls should be light color as gives more reflection from the safety light.

Darkroom Safelight Appropriate lighting in darkroom is

crucial to good film development. “Safe” light means light will not affect

the film. Safelights use a small-wattage bulb

and a special filter to eliminate the light from the blue and green spectrum. Bulb should be 15 watts or less.

Safelights continued Should be positioned so that darkroom

work can be performed without fumbling. Two types of safe-lighting

Direct Diffused light that shines directly over a work

area such as the dry or wet side of the darkroom.

Indirect A filtered light directed toward the ceiling and

reflected over the entire room. Two types of lighting may be combined.

Safelights continued

Safelight should never be closer than 4 feet to work area.

If too close may cause some film fog.

Film-Processing Solutions

Film processing consists of five basic steps. 1. Developing 2. Rinsing or stop bath 3. Fixing 4. Washing 5. Drying

Chemicals

May be purchased in a variety of ways (liquids or powders).

May be in concentrated form and need to be diluted or mixed.

Preparing chemicals correctly is important or resulting solution may adversely affect the radiographic product.

Chemicals continued Chemicals should be kept at specified

room temperature. Variances may adversely affect the

radiographic product. Too low temps, some of the chemicals

may become sluggish in action and produce an under-developed or under-fixed radiograph.

Too high temps, may be too hot for manual control.

Chemicals All chemicals should be kept at same

temperature. Variances in temperature between the

chemicals can result in film reticulation. Reticulation- a darkroom artifact produced by

variable chemical temperatures that cause irregular expansion and contraction of the film emulsion, resulting in a mottled density appearance.

Reticulation

The Developer Developer-a chemical solution that

converts the latent image to a visible image.

Primary function is to convert the exposed silver halide crystals to black metallic silver.

Developing time is specified by chemical manufacturer. Be sure to know this in your practice.

The Developer Continued

Developer temperatures affects the developing time.

Time-temperature developing is preferred over visual inspection when using manual processing.

Developer consists of developing agents, accelerators, preservatives, restrainers, hardeners, and a solvent.

Developing Agents

Composed of chemical compounds such as hydroquinone or phenidone that can convert exposed grains of silver halide to black metallic silver. The developing agent has little or no effect on the unexposed silver halide crystals.

Accelerators

Chemicals that increase the activity of the developer. Substances such as potassium carbonate or sodium carbonate are used to increase the pH to an alkaline range of 9.8 to 11.4. This increase in pH causes the emulsion to swell and soften, allowing the developing agent to work more effectively.

Preservatives

Prevent the rapid oxidation that can occur with alkaline developing agents. They also help maintain a stable development rate and prevent straining of the emulsion layer.

Restrainers

Limit the action of the developing agent to the exposed silver bromide crystals in the film.

Hardeners

Often added to developers in automatic processors. They harden the film during processing and prevent excessive swelling of the emulsion. If the gelatin emulsion were to swell extensively, it could be damaged by the rollers in the automatic processor.

Solvent

Consists of water to dissolve the chemicals.

The Rinse Bath After film is in Developer, retains a

substantial amount of developer in the gelatin.

If film went straight from developer to fixer, then alkaline developer would neutralize acid of the fixer.

Rinse bath serves to stop the developing process, rinse the developer from film, and prevent carryover contamination to the fixer.

The Fixer

Serves two basic functions 1. Clears unexposed silver halide crystals

from the film. 2. It hardens the gelatin coating so that it

can be dried without damaging the film surface.

General guideline is that film should be fixed for twice the development time.

Fixer consists of Clearing or fixing agents

Dissolve and remove unexposed silver halide crystals from the film emulsion.

Preservatives Prevent decomposition of the fixing agent.

Hardeners Prevent excessive swelling of gelatinous

emulsion during fixation procedure and softening during the wash procedure. Shorten drying time.

Fixers Composition Continued Acidifiers

Compounds that accelerate action of other chemicals and neutralize any alkaline developer possibly carried over into the acidic fix solution.

Buffers Chemical compounds added to the solution to

maintain the desired pH. Help to stabilize the acidity against the addition of alkaline developer carryover. Without buffer, developer would neutralize fix solution. Can also prevent sludge formation in the fix bath.

Fixer Composition continued

Solvent Consists of water. Purpose is to dissolve other ingredients

and assist in the fixing agent to diffuse into the emulsion layer of the film.

Carried silver halide away from film.

The Wash bath Wash portion is vital to a quality

radiograph. If film is not washed properly for a long

enough period of time, the image will eventually discolor and fade.

Films should be washed in circulating water so both surfaces of film receive water continuously.

Manual processing wash time is recommended 20-30 mins.

Wetting Agent

Water spots and streaks is a problem with drip drying films in manual processing.

A wetting agent bath can hasten drying process. Called Surface-tension reducing agent.

Water spots/bubbles

Solution Replenisher In manual processing, chemical depletion is

a natural result of chemical carryover into adjacent tanks. Up to 60 mL of developer can be carried on a

film into rinse bath. Developer and fixer need frequent

replenishment. Replenishment is available in powder and liquid

concentration form. Generally will have higher concentration than

original solution in order to maintain chemical potency.

Solution Replacement Used/old chemicals are primary cause

of poor-quality radiographs. Check chemicals every time PRIOR to

development of film. Developer may turn from green to

brown. In general, chemicals should be

changed every 4-6 weeks. Depends on frequency of use.

Biologic Growth

In manual processing may have bacterial growth.

Need to be controlled. When changing chemicals, clean

tanks as well. Wash tank of automatic processor

should be drained at end of day to prevent growth.

Film-processing Techniques

Two types of processing: Manual

May take up to an hour to develop Automatic

Generally can be processed in 90 seconds

Both types of processing can produce a quality radiograph, it is a matter of preference.

Manual-Processing Procedure Step 1.

Preparation Make sure that chemicals should be at

proper temperature and should be stirred.

Step 2. Unloading the cassette

Take care when unloading cassette. Careful with fingernails! (Why?)

X-ray film should be handled by corners and edges only.

Manual Processing Procedure cont.

Step 3. Loading the film on a hanger Clip hanger – load the bottom first

Stretch to “bounce a coin on it” Will prevent the film from touching other films or

walls while developing Channel hanger

Held in one hand while sliding the film into the channels with the other

All sides and corners should be checked for proper placement

Once in place, the top can be closed

Manual Processing Continued

Step 4. Developing the film

Immersed in developing tank and agitated two or three times.

Step 5. Rinsing the film

Remove film from developer. Immerse in rinse bath and agitated for 30

seconds.

Over-rinsed film

Manual Processing Cont.

Step 6. Fixing the Film

Removed from rinse tank and immersed in the fix tank.

Step 7. Washing the Film

Removed from Fixer and washed 20-30 mins.

Left in Fixer

Under washed film

Manual Processing cont.

Step 8. Optional Final Rinse

Application of a wetting agent.

Step 9. Drying the film

Film is dried in dust-free environment to prevent artifacts.

Make sure well seperated.

No Final Wash Applied

Automatic Processing

Advantages over the manual method. 1. highly standardized procedure with

consistent quality. 2. can produce a dry radiograph in a

short amount of time. 3. reduces labor time of employees. 4. smaller darkroom space required.

Automatic Processors

Roughly same procedure as manual processing.

Operate at higher temps and have specifically formulated chemicals to speed development.

Film is transported through processor by a series of rollers.

Automatic Processor continued

Chemicals still need to be checked and processor warmed up.

Make sure that films are fed one at a time to prevent sticking together.

Will be signaled by the processor when can feed next film.

Stuck in processor

Films stuck together

Folded Film

Processing Chemicals

In automatic processing, chemicals are replenished as they are used.

Temperature is also constantly monitored.

Chemicals are re-circulated.

Processor Maintenance

Can be serviced by a professional Quick tech checks:

Check solution levels Check replenishment rate Check temperature Check roller operation Rinse and wipe rollers racks Clean tanks

Silver Recovery

Recycle to obtain silver from development process. 3 methods of silver recovery

1. Metallic replacement 2. Electrolyte recovery 3. Chemical precipitation

Film Identification

Proper Labeling and identification of x-ray films is VITAL!!!!!

All labeling systems should include. 1. name and address of hospital practice

or veterinarian. 2. date the radiograph was take. 3. patient identification including name

of the owner and patient name, age, sex, and breed.

Lead Blockers Identification can

be done via lead lettering, lead impregnated tape, or photoimprinting labels.

Other markers

Right (R) and Left (L) markers are essential to identify size and position of image on radiograph.

May need to label front and rear as well especially in large animals.

If label not a part of film itself,then can add later with marker, or scratching into film while still wet.

See markers

Film Filing

Organized film filing system is needed in veterinary practice.

Must be placed in suitable holder and filed appropriately. Should be labeled, numbered if

necessary and filed correctly for easy future reference.

X-ray logs also help with film identification.