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DENTAL X-RAY FILM PROCESSING

BY:DR.MEELU LAMBAPG 1ST YEAR

ORAL MEDICINE AND RADIOLOGY

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CONTENTS• INTRODUCTION

• FILM PROCESSING STEPS

• FILM PROCESSING SOLUTIONS

• PROCESSING ROOM

• EQUIPMENT REQUIREMENTS

• GENERAL SAFETY RULES OF DARK ROOM

• MOUNTING OF RADIOGRAPHS

• WASTE MANAGEMENT OF DARK ROOM

• SUMMARY

• REFERENCES

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INTRODUCTION

• Film processing refers to a series of steps that produce a visible permanent image on a dental radiograph.

• AIMS OF PROCESSING

-To convert the latent image (invisible) on the film into a visible image.

-To preserve the visible image so that it is permanent and does not disappear from the dental radiograph.

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PROCESSING METHODS

A.) Manual Processing: Three methods

• Time temperature method• Modified time temperature method• Visual method

B.) Automatic Processing

C.) Day Light Processing

D.) Self Developing Films

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MANUAL FILM PROCESSING STEPS

• Consists of following five steps:

i) Development

ii) Rinsing

iii) Fixing

iv) Washing

v) Drying

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DEVELOPEMENT

-A chemical solution developer is used in the development process.-Development is a chemical process that amplifies the latent image by a

factor of millions (about 100,000,000) to form a visible silver pattern.-The basic reaction is reduction (addition of an electron) of the silver ion,

which changes it into black metallic silver.Ag+ + electron Ag.(Silver ion in crystal + (electron from silver atoms.containing latent image ) developer)

Purpose Of Developer

-the exposed, energized silver halide crystals chemically into black metallic silver.

-Softens the film emulsion during the process.

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RINSING

A continous, gentle rinsing for 30 sec in water is necessary after developing

i)To dilute the developer and slowing the developement process

ii)To remove alkali activator.

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FIXING

A chemical solution fixer is used in the fixing process.

Purpose of Fixer

-Remove the unexposed, unenergized silver halide crystals from the film emulsion.

-Hardens the film emulsion during the process.

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WASHING

Necessary to thoroughly remove all the excess chemicals from the emulsion.

DRYING

- Should be air dried at room temperature in a dust free area.- Must be completely dried before they can be handled for mounting

and viewing.

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Time temperature method :

• Before processing check the levels of developer and fixer solution.

• If the solution level is low add fresh solution.

• Never add water to raise the level of the solution, as it dilutes the strength of chemicals.

• Stirring the processing solution with a stirring rod or paddle.

• Stirring the solution mixes the chemicals and regularizes the temperature of the solution.

• Check the temperature of the developer solution. The optimum temperature for developer is between 650 F to 750 F. If the temperature of the developer solution is outside this range circulating water tap must be regularized to adjust the tap and sufficient time must be allowed to reach the correct temperature.

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• Close and lock the dark room turn off the overhead white light and turn on the safelight.

• Remove the exposed film from its lightproof packet, using only safe light illumination.

• Hold the film only from their edges.

• Clip the bare film to the hanger clip( 1 film to a single clip ).

• Based on the temperature of developer solution and the instruction of manufacture, set the timer. A time-temperature chart is used to determine the time.

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• Immerse the film hangers with the films into developer solution.

• Film must not contact one another or the sides of the processing tanks during development.

• Gently agitate the film hanger up and down, Several times to prevent air bubbles from dinging to the film.

• Hang the film hanger on the edge of the insert tank and make serve that all the films immersed in the developer.

• Activate the timer and cover the processing tank.

• When the timer goes off, cover off the processing tank, remove the film hanger with film from the developer solution, and place it in the circulating water of the rinsing tank.

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• Immerse the film hangers with films in fixer solution and gently agitate it for 5 seconds every 30 seconds. This eliminates air bubbles and brings fresh fixer in touch with emulsion.

• When the timer goes off uncover the processing tank and remove the films from the fixer and drain excess of fixer into the wash bath.

• The films are then placed in running water for atleast 10 min.

• Further surface moisture is removed by gently shaking off the excess water form the film and the hanger.

• Dry the film in circulating, moderately warm air.

• If a heated drying cabinet is used the temperature should not exceed 1200 F.

• Remove the dry radiographs from the film hangers and use a view box to examine the radiographs and place then in an envelope labeled with patients name and date of exposure.

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Modified time temperature method :

• In this method depending upon the temperature of solution, the developing time is divided on daily basis.

• A table or a chart can be prepared by specifying developing time for a range of daytime temperature.

Advantage :• Temperature need not be maintained at particular level and at

the same time consistent image quality can be gained.

Disadvantage :• For every brand of developer separate time temperature chart

should be prepared.

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Visual method :

• In this method the exposed x-ray film is immersed in developing solution. For about 10 sec and then removed and observed in the safe light.

• If adequate image have been obtained then it is put for rinsing, other wise re-inserted in the developing solution till adequate image is obtained.

Disadvantage : This method is highly objective in nature and doesn’t give consistent quality.

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AUTOMATIC PROCESSING

-Prepare darkroom, if daylight loader is not part of automatic processor.

-Close and lock the door of darkroom.

-Turn off the overhead white light, and turn on the safelight.

-For intraoral films, carefully unwrap each exposed film over a clean working surface.

-For extra-oral films carefully remove the film from the cassette.

-Handle all the films by the edges only.

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-Insert each unwrapped film into the film feed slot of the processor, one at a time.

-Allow at-least 10 sec between the insertion of each film.

-Do not turned the films sideways or insert too quickly, they will overlap; overlapped films results in non diagnostic radiographs.

-After films are inserted, allow 4-6 min for automated processing to occur.

-Retrieve the processed radiographs from the film recovery slot on the outside of the automatic processor.

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ADVANTAGES

• Time saving .

• Constant film quality is achieved, due to fixed processing cycles.

• Need for dark room is eliminated.

• Less floor space is required.

• Chemicals can be replenished automatically by machine.

• Large number of films can be processed continuously.

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DISADVANTAGES

• Equipment is relatively expensive.

• Strict maintenance and regular change is required, dirty rollers produce marked films.

• Films may get lost in the tank

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Day Light Processing Method

-Any processing method that doesn’t need a dark room is called as daylight processing method.

-Both manual and automatic processing can be executed in this manner.

-Manual day light processing involves stripping the film inside a light proof pouch.

-Then processing steps are carried out manually as usual but in daylight.

-If an automatic processor has a daylight-loading chamber and since the entire assembly is enclosed in a light proof contains, it also can be called as daylight processing method.

-Elimination of need for a darkroom is the only advantage in this method.

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SELF DEVELOPING FILMS

-Self-developing films are an alternative.

-The x-ray film is presented in a special sachet, containing developer and fixer.

-Following exposure the developer tab is pulled, unveiling developer solution, which is milked down towards the film and massaged around it gently.

- After about 15 seconds, the fixer tab is pulled to release fixer solution, which is similarly milked down to the film.

-After fixing the used chemicals are discarded and the film is rinsed thoroughly under running water about 10 minutes.

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Advantages :

• No dark room or processing facilities are needed. • Time saving.

Disadvantages :

• Poor over all image quality. • Image detoriates rapidly over time. • No lead foil inside the film hence less flexible and can

be easily bent .• These films are difficult to use in position holders. • Relatively expensive

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FILM PROCESSING SOLUTIONS• Obtained in following forms :i) Powderii) Ready to use liquidiii) Liquid concentrate-Both powder and liquid concentrate forms must be mixed with distilled water.-Liquide concentrate form is popular-easy to mix and occupies little storage space.-Fresh chemical solutions produce the best radiographs.

To Maintain Freshness: i)Solutions must be replenished daily.ii)Must be changed after every 3-4weeks.

Two special chemical solutions are necessary for film processing:iv) Developerv) Fixer

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DEVELOPING SOLUTION:i) Developerii) Preservativeiii) Acceleratoriv) Restainer

FIXER SOLUTION:v) Fixing agentvi) Preservativevii) Acidifierviii) Hardening agent

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DEVELOPING SOLUTION

I.) DEVELOPER

- Developing solution convert the exposed silver halide crystals into black metallic silver grains.

- This process begins at latent image sites.

- At latent image site, electrons from the developing agents are conducted into the silver halide crystals and reduces the constitute silver ion to solid grains of metallic silver.

- Unexposed silver halide crystals, are unaffected during the time of reduction of exposed crystals into metallic silver.

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2 components of developing solution:

i) Phenidone

- First electron donor

- This electron transfer generates the oxidized form of phenidone.

ii) Hydroquinone

- Provides an electron, to reduce the oxidized phenidone back to its active state, so that it can continue to reduce silver halide grains to metallic silver.

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II.) ACTIVATOR

- Alkaline in nature

- Developing agents are active only at alkaline PH values( high PH) .

- Achieved by adding alkali compoundsa.) Sodium or potassium hydroxideb.) Buffer-sodium bicarbonate

- This causes the gelatin to swell so that developing agents easily diffuse with emulsion.

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III) PRESERVATIVE

- Sodium sulfite (antioxiant)

- Prevents oxidation of developing agents

- Preservative is added with ‘brown oxidized developer’. This makes the solution colourless.

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IV) RESTAINER

- Potassium bromide and Benzatriazole.

- Prevents the developement of unexposed silver halide crystals

- It depresses the reduction of both exposed and unexposed silver halide crystals but are more effective in reduction of unexposed silver halide crystals.

- The restainer acts as ‘antifog agent’ and increases the contrast.

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DEVELOPER REPLENISHER

-During normal course of film processing:i)Phenidone and hydroquinone are consumed from solution.ii)Bromide ions and byproducts are released into the solutioniii)Developer solution gets inactivated by exposure of oxygen.

-These actions produces a seasoned solution.

-Hence developer sol must be replenished daily to prolong the life of seasoned solution

-Recommended amout-8 ounces/gallon of developer solution.

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FIXING SOLUTIONI)CLEARING AGENT- Ammonium thiosulfate

- Dissolves and removes the unexposed silver halide grains.

- Ammonium thiosulfate forms a stable, water soluble complexes with silver ions (silver thiosulfate complex), which then diffuses from the emulsion.

- Thiosulfate does not have a rapid effect on the metallic silver grains in the film emulsion

- But excessive fixation results in loss of film density, because the grains of silver slowly dissolve in the acetic acid of fixing solution.

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II.) ACIDIFIER

-Contains an acetic acid buffer system (PH 4-4.5)

-This acidic PH required for a.) good diffusion of thiosulfate into the emulsionb.) silver thiosulfate complex out of the emulsion.

- Inactivate any carryover developing agents in the film emulsion, hence blocks the further development of any unexposed crystals.

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III.) PRESERVATIVE-Sodium sulfite

-Prevents oxidation of clearing agents as they are unstable in the acidic environment of fixing solution.

-Binds with any colored oxidized developer carried over into the fixing solution, and removed it from the solution.

-This prevents oxidized developer from staining the film.

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IV.) HARDNER

- Aluminium sulfate

- This complexes with gelatin and hardens the gelatin during fixing process.

- reduces the swelling of emulsion ↓ Lessens mechanical damage to the emulsion - Limits water absorption ↓ shortening drying time.

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PROCESSING ROOM REQUIREMENTSA well planned dark room makes the processing easier, which should be of

atleast 4 × 5 feet (1.2 × 1.5 m ).

Characteristics of darkroom :

i) Convenient location and adequate size

ii) Ample working space with adequate storage

iii) Lighting

iv) Temperature and humidity controlled

v) Darkroom plumbing

vi) Miscellaneous

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LOCATION-Darkroom should be located near the area where the x-ray units are installed.

SIZE-darkroom size is determined by the following factors:-Volume of radiographs processed & Number of persons using the room.

WORKING SPACE-Adequate counter area where films can be unwrapped.-A clean, organized work area is essential which should be free of

processing chemicals, water, dust, and debris.

STORAGE SPACE-Adequate space for storage for chemical processing solutions, film

cassettes etc.

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LIGHTING-The room must be completely dark and must exclude all visible light.-Any leaks of white light in the darkroom causes film fog.

• Two types of lighting are essential in darkroom.i)Room lighting (white illumination) and ii)Safe lighting.

Room lighting :Incandescent room lighting is required to perform task such as cleaning, stocking materials and mixing chemicals, this is not associated with the act of processing films.

Safe lighting :- Special kind of lighting of relatively long wavelength and low intensity

illumination that does not rapidly affect open film but permits one to see well enough to work in the area.

- To minimize the fogging effect of prolonged exposure, the safe light should have a 15 W bulb and a safe light filter(red GBX-2 filter ).

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-It should be mounted atleast 4 feet (1.2 metes) above the surface where films are handled.

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TEMPERATURE AND HUMIDITY-Should be controlled to prevent film damage.-Room temp of 70 degree F is recommended ; if exceeds 90 degree

F,film fog results.-Humidity level of between 50 and 70 percent should be maintained;

when too high, film emulsion does not dry; when too low, static electricity becomes a problem and causes film artifacts.

DARKROOM PLUMBINGMust include both hot and cold running water along with mixing valvesto adjust the water temperature in the processing tanks with utility sink.

MISCELLANEOUS REQUIREMENTS: i)Wastebasket for disposal of all film wrappings.ii)x-ray view box used to examine radiographs.

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EQUIPMENT REQUIREMENTS

• Manual Processing tanks

• Timer

• Thermometer

• Film hangers

• Miscellaneous equipments

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MANUAL PROCESSING TANK-Has 2 insert tanks and 1 master tank-Constructed of stainless steel-Does not react with processing solutions and easy to clean.-practical size for a master tank in dental office is about 20 × 25 cm

INSERT TANKS:-2 removable 1-gallon ( 3.8 L) insert tanks hold the developer and fixer solutions,

placed in master tank.-Developer solution is placed on the left and fixer solution placed on right in the

master tank.-Water in master tank seperates the two insert tanks.

MASTER TANK:-Filled with circulating water.-An overflow pipe is used to control the water level in the master tank.

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TIMER:

- A timer is use to signal the radiographer that the films must be removed from the current processing solution.

- Development time depends on the temperature of the developer solution.

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THERMOMETER-Use to determine the temperature of developer solution; optimum

temp is 68 degree F, below 60 degree F chemical works too slowely, results in under development; above 80 F chemical works too rapidly, will cause film fog.

-Floating thermometer or one that is clipped to the side of the developer tank may be used.

-Temperature of developer sol, determine the development time.

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FILM HANGERS-Also known as processing hangers.

-Device equipped with clips used to hold films during processing.

-Made up of stainless steel.

-Available in various sizes and can hold upto 20 intraoral films.

MISCELLANEOUS EQUIPMENTS

i) Stirring rods-made up of plastic or glass use to stirr the developer an fixer solutions, and equalizes the temperature of the solutions.

ii) Plastic apron-use to protect clothing during the processing of films and mixing of chemicals.

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AUTOMATIC PROCESSOR (Uses a roller transport system)

PROCESSOR HOUSING: -Encases all the the component parts of the automatic processor.

FILM FEED SLOT: -Opening on the outside of the processor housing used to insert unwrapped

films into the automatic processor.

ROLLER FILM TRANSPORTER:- System of rollers ( propelled by motor driven gears and belts) used to move

the film rapidly through the developer, fixer, water, and drying compartments.

- Rollers produces wrining action that removes the excess solution from the emulsion.

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DEVELOPER COMPARTMENT:

-Holds the developer solution.

-Developing solution is Specially formulated for automatic processor and different from developing solution used in manual processing.

-A hardening chemical ‘glutaraldehyde’ is added to the conventional manual processing developing solution, to prevent the emulsion from softening and sticking to the solution.

-Sulfate compounds are also added to the manual processing developer, to minimize the swelling of the emulsion, so that the films can be transported by the roller uniformly.

-Because the total processing time is reduced in automatic processing, the chemical concentration and temperature of the developing solutions must be increased.

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FIXING COMPARTMENT:

-Holds fixer solution

-Film directly transfer to fixer from developer without rinsing step.

-In fixer solution, the film is rapidly fixed and then hardened.

-Fixing solution is Specially formulated for automatic processor and different from fixing solution used in manual processing.

-Fixing solution for automatic processor is highly concentrated chemical solution, that contains additional hardening agents.

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WATER COMPARTMENT: Holds circulating water, used to wash the films after fixation.DRYING CHAMBERS: Holds heated air, used to dry wet film.FILM RECOVERY SLOT: Opening on the outside of the processor housing, where the dry,

processed radiograph emerges from the automatic processor.

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GENERAL SAFETY RULES IN DARKROOM

• Limit access to the darkroom. Only approved persons with safety training should be allowed to work in the room.

• Keep the work area clean.

• Wet and dry areas should be clearly separated.

• Always segregate chemicals.

• Do not store chemicals on the floor.

• Do not eat, drink or smoke in the darkroom.

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• The darkroom should be well ventilated (10 – 20 air changes per hour).

• Always wash hands with soap and warm water after working with chemicals.

• Always Add Acid to water, never water to acid. (Remember ‘AAA’)

• Label all containers.

• Keep all containers and trays closed or covered when not in use to prevent the release of toxic gases.

• Do not use paper towels or to clean up acid spills as this may cause a fire .

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MOUNTING RADIOGRAPHS• Radiographs must be preserved and maintained in the most

satisfactory and useful condition.

• Periapical, interproximal, and occlusal films are best handled and stored in a film mount.

• Mounts are made of plastic or cardboard and may have a clear plastic window that covers and protects the film.

• However, the window may have scratches or imperfections

that interfere with radiographic interpretation

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• The operator can arrange several films from the same individual in a film mount in the proper anatomic relationship.

• The preferred method of positioning periapical and occlusal films in the film mount is to arrange them so that the images of the teeth are in the anatomic position and have the same relationship to the viewer as when the viewer faces the patient.

• The radiographs of the teeth in the right quadrants should be placed in the left side of the mount and those of the left quadrants in the right side.

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WASTE MANAGEMENT OF DARK ROOM

• The primary ingredient of concern in processing solutions is the dissolved silver found in used fixer.

• Another material of concern is the lead foil found in film packet.

• Several means are available for properly disposing of the silver and lead. Silver may be recovered from the fixer by using either metallic' replacement or electroplating methods.

• Metallic replacement uses cartridges through which waste solutions are poured. In this process, iron goes into the solution and the silver precipitates as a sludge.

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• In the electroplating method, the waste solutions come in contact with two electrodes, through which a current passes. The cathode captures the silver. In either case, the scrap silver can be sold to silver refiners and buyers.

• The lead foil "is separated from the packets and collected until enough has been accumulated to sell to a scrap metal dealer. Dental offices also should consider using companies licensed to pick up waste materials.

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SUMMARY• Film processing refers to a series of step that produce a visible

permanent image on a dental radiograph.

• The pattern of stored energy on an exposed film is termed as a latent image, this image remains invisible until it undergoes processing.

• The visible image that result on a dental radiograph is made up of black, white or gray areas.

• Their are five steps of film processing: development, rinsing, fixation, washing, drying.

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• A darkroom is a completely dark room where x ray films can be handled and processed to produce diagnostic radiographs.

• The ideal darkroom can be conveniently located, adequate size, equipped with correct lighting and ventilation, and arranged with ample working space and storage.

• The dark must be light tight and must include proper safe light.

• Manual processing and automatic processing are the practical

processing methods used for processing.

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REFERENCES

• White S.C, Pharoah M.C. Oral Radiology-principles and interpretation;2011:6th ed.

• Haring Joen M. Lannucci, Howerton Laura Jansen. Dental Radiography-Principles and Techniques;2006:3rd ed.

• Langland Olaf E.,Langlais Robert P.,Preece John W. Principles Of Dental Imaging;2002:2nd ed.

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