DENTAL X-RAY FILM PROCESSING
PG 1ST YEAR
ORAL MEDICINE AND RADIOLOGY
• FILM PROCESSING STEPS
• FILM PROCESSING SOLUTIONS
• PROCESSING ROOM
• EQUIPMENT REQUIREMENTS
• GENERAL SAFETY RULES OF DARK ROOM
• MOUNTING OF RADIOGRAPHS
• WASTE MANAGEMENT OF DARK ROOM
• REFERENCES 2
• 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
-To preserve the visible image so that it is permanent and does
not disappear from the dental radiograph.
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
MANUAL FILM PROCESSING STEPS
• Consists of following five steps:
-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
-Softens the film emulsion during the process. 6
A continous, gentle rinsing for 30 sec in water is
necessary after developing
i)To dilute the developer and slowing the
ii)To remove alkali activator.
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.
Necessary to thoroughly remove all the excess chemicals from the
- Should be air dried at room temperature in a dust free area.
- Must be completely dried before they can be handled for mounting
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.10
• 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
• 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. 11
• Immerse the film hangers with the films into developer
• 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
• 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.
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.
• Temperature need not be maintained at particular level
and at the same time consistent image quality can be
• For every brand of developer separate time
temperature chart should be prepared. 15
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.
-Prepare darkroom, if daylight loader is not part of automatic
-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. 17
-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
• Time saving .
• Constant film quality is achieved, due to fixed processing
• 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.
• Equipment is relatively expensive.
• Strict maintenance and regular change is
required, dirty rollers produce marked films.
• Films may get lost in the tank
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
-Manual day light processing involves stripping the film inside a
light proof pouch.
-Then processing steps are carried out manually as usual but in
-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
SELF DEVELOPING FILMS
-Self-developing films are an alternative.
-The x-ray film is presented in a special sachet, containing developer and
-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.
• No dark room or processing facilities are needed.
• Time saving.
• 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
FILM PROCESSING SOLUTIONS
• Obtained in following forms :
ii) Ready to use liquid
iii) 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:
- 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.
2 components of developing solution:
- First electron donor
- This electron transfer generates the oxidized form of
- 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.
- Alkaline in nature
- Developing agents are active only at alkaline PH
values( high PH) .
- Achieved by adding alkali compounds
a.) Sodium or potassium hydroxide
b.) Buffer-sodium bicarbonate
- This causes the gelatin to swell so that developing
agents easily diffuse with emulsion.
- Sodium sulfite (antioxiant)
- Prevents oxidation of developing agents
- Preservative is added with ‘brown oxidized
developer’. This makes the solution colourless.
- Potassium bromide and Benzatriazole.
- Prevents the developement of unexposed silver halide
- 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
-During normal course of film processing:
i)Phenidone and hydroquinone are consumed from solution.
ii)Bromide ions and byproducts are released into the solution
iii)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.
- 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
- 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.
-Contains an acetic acid buffer system (PH 4-4.5)
-This acidic PH required for
a.) good diffusion of thiosulfate into the emulsion
b.) 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.
-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.
- Aluminium sulfate
- This complexes with gelatin and hardens the gelatin during fixing
- reduces the swelling of emulsion
Lessens mechanical damage to the emulsion
- Limits water absorption
shortening drying time.
PROCESSING ROOM REQUIREMENTS
A 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
iv) Temperature and humidity controlled
v) Darkroom plumbing
vi) Miscellaneous 36
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.
-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.
-Adequate space for storage for chemical processing solutions, film
-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
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 ).
-It should be mounted atleast 4 feet (1.2 metes) above the surface
where films are handled.
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.
Must include both hot and cold running water along with mixing valves
to adjust the water temperature in the processing tanks with utility sink.
i)Wastebasket for disposal of all film wrappings.
ii)x-ray view box used to examine radiographs. 40
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
-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
-Water in master tank seperates the two insert tanks.
-Filled with circulating water.
-An overflow pipe is used to control the water level in the master tank.
- A timer is use to signal the radiographer that
the films must be removed from the current
- Development time depends on the
temperature of the developer solution.
-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.
-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.
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. 46
AUTOMATIC PROCESSOR (Uses a roller transport system)
-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
- Rollers produces wrining action that removes the excess solution from the
-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
-Because the total processing time is reduced in automatic processing, the chemical
concentration and temperature of the developing solutions must be increased.
-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.
Holds circulating water, used to wash the films after fixation.
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.
GENERAL SAFETY RULES IN
• 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. 51
• The darkroom should be well ventilated (10 – 20 air changes per
• Always wash hands with soap and warm water after working with
• 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 . 52
• 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
• The operator can arrange several films from the same
individual in a film mount in the proper anatomic
• 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.
WASTE MANAGEMENT OF DARK
• 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.
• 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.
• 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
• 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.
• 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.
• 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
• Langland Olaf E.,Langlais Robert P.,Preece John
W. Principles Of Dental Imaging;2002:2nd ed.