11 Film Processing Techniques










122
11
Film Processing Techniques
EDUCATIONAL OBJECTIVES
Upon completing this chapter, the student will be able to:
1. Dene the key terms listed at the beginning of the
chapter.
2. Explain the steps in manually processing dental lm.
3. Describe the following related to the design and
requirements of the darkroom:
• Describewhatadarkroomisusedforandwhatthe
components of an acceptable darkroom are.
• Knowthetypesoflightingthatareinadarkroom.
• Explainwhatasafelightisandwhatthecoin test is
used for.
• Discusstheplumbingofthedarkroom.
• Discussthecontentsofthedarkroom,including
processingtanks,solutions,replenishingsolutions,
timerandthermometer,lmhangers,anddryers.
• Discussthesequenceformanualandautomatic
processingandtherolesofthedeveloper,xer,and
water in both methods.
4. Explainanddiscussthedevelopmentprocess,
including:
• Denethetermlatent image, and discuss how it
is dierent from the visible image in dental lm
processing.
• Describetheproceduresformanualandautomatic
processing.
5. Describethetime-temperaturedevelopmentmethod,and
compare it to the sight development method.
6. Explain the indication for use of rapid processing, and state
what the components of this method are.
7. State the importance of the care and maintenance of the
darkroom and automatic processors and how they are
included in a quality assurance program in dental
facilities.
8. Discuss the environmental concerns that are associated
with lm processing.
9. Knowwhatautomaticprocessingis,aswellasdescribethe
steps involved in automatic processing.
10. Knowthecommonprocessingerrorsformanualand
automatic processing and how to remedy each error.
familiarity with the manual and automatic lm processing
techniques continues to be included in dental radiology
education. is chapter discusses manual and automatic
processing, the components of a darkroom, the funda-
mentals of processing, common processing errors, lm
processing quality assurance, and environmental concerns
in dental lm processing.
Introduction
Although the use of digital radiographic techniques are on
the rise in dental facilities, conventional lm-based radi-
ography is still being used. While lm processing is slowly
becoming a technique of the past, the basic knowledge
and understanding of lm processing is still required in a
thorough study of dental radiography. e fundamental
KEY TERMS
automatic processing
clear lm
coin test
dark image
darkroom
daylight loader
dense image
developer
developer cuto
drying rack
electrostatic artifact
lm hanger
lm roller
xer
generators
latent image
light leak
light-tight
manual processing
overdeveloped
rapid processing
reference lm
replenisher
reticulation
safelight
sight development
stop bath
thermometer
thermostatic valve
thin image
time-temperature technique
torn emulsion
underdeveloped lm
visible image
water bath
wet reading

123CHAPTER 11 Film Processing Techniques
or both); and (4) the space required for duplicating, drying,
and storage.
e walls of the darkroom should be a light color that
reects the safelighting; darkroom walls do not have to
be black. e surfaces of the walls and oor should be of
materials that are resistant to staining and can be cleaned
of the processing solutions that inevitably spill or splash
onto them.
e darkroom must be completely light-tight so that
when the safelight is on, it is the only illumination in the
darkroom. Because x-ray lm is sensitive to white light,
any light leaks can fog the lm. A fogged lm is less diag-
nostic and in some cases may be useless. e easiest way to
check for light leaks is to stand in the darkroom in com-
plete darkness; any leaks around the door or in other areas
will be apparent and should be corrected. e darkroom
door should have an inside lock so that the door cannot be
opened from the outside while lms are being processed.
ere are also darkrooms with solid revolving doors to pro-
hibit light from entering the room during processing as well.
It is advised that the darkroom should be well ventilated
to exhaust the moisture from the drying lms or the heat, if
a dryer is used, and maintain comfortable working condi-
tions. Keeping the darkroom at a reasonable temperature
makes it easier to maintain desired processing solution tem-
peratures. Another consideration to maintain lm quality is
to avoid storing unexposed lm in the darkroom cabinets,
because at high temperatures (greater than 90° F) the lms
can experience lm fog.
Lighting
A well-designed darkroom has ve dierent light sources:
(1) an illuminating safelight, (2) an overhead white light,
(3) a viewing safelight, (4) an x-ray viewbox, and (5) an
outside warning light.
Illuminating Safelight
When lm packets are opened, lm is attached to hangers,
or lm is being processed, safelight conditions must be
maintained. As mentioned, white light darkens x-ray lm.
Safelight is any illumination that does not aect the x-ray
lm (Fig. 11.1). It is a low-intensity light composed of long
wavelengths from the orange/red range of the spectrum.
Manual Processing
e processing of exposed x-ray lm (either manually or
automatically) is an important step in the radiographic
chain of events. It is at this point that a visible image is
produced, from which a diagnosis can be made. e x-rays
that have penetrated the hard and soft tissue in the patient’s
mouth have created a latent image on the exposed x-ray
lm. e processing of this lm converts the latent image
to a visible diagnostic image.
Manual processing can occur inside or outside of the
darkroom. In the darkroom, manual processing is per-
formed with the required armamentaria, including manual
processing tanks, processing solutions, proper lighting,
lm-holding hangers, a thermometer, and other needed
equipment. It should be noted that with increased use of
digital radiography, the need for a darkroom has become
less necessary (see Chapter 15).
e darkroom is a room in the dental oce set aside for
radiographic processing. In addition to processing lm, the
dental professional must keep the darkroom clean, change
solutions regularly, keep accurate records of processed
radiographs, and maintain a quality assurance program. It
is important to realize that the processing of lms is vital
in the production of the diagnostic radiograph. Errors in
the darkroom can easily ruin what would otherwise have
been diagnostic radiographs, making it necessary to retake
the lms with the resultant loss of time and increased radia-
tion exposure to the patient. It is important to remember
that every lm that requires retaking doubles the patients
radiation exposure for that lm. An acceptable chairside
radiographic technique must be coupled with an equally
acceptable processing technique. e importance of elimi-
nating darkroom errors should be uppermost in the minds
of dental professionals.
Design and Requirements of
the Darkroom
e essential requirements and components of a darkroom
that is used for manual processing are that it should be
light-tight and have safelight and white light illumination,
processing tanks, a thermostatically controlled supply of
water, thermometer, timer, lm hangers, drying racks, and
storage space.
Location and Size
e darkroom should be a space unto itself, located near the
rooms in which the x-ray units are placed. e darkroom
should be a minimum of 16 square feet (4 × 4), allowing
enough room for one person to work comfortably. e
factors that should be considered in determining the space
needed are (1) the volume of radiographs to be processed; (2)
the number of dental professionals handling the processing;
(3) the type of processing to be done (manual, automatic,
Figure 11.1 A variety of safelights are available for use in the
darkroom including safelights now available in LED format for intraoral
and extraoral lms. (Courtesy Carestream Health, Rochester, NY.)

124 CHAPTER 11 Film Processing Techniques
As shown in Chapter 4 in the discussion of intensifying
screens, x-ray lms are more sensitive to the blue/green
region of the light spectrum, where the wavelengths are
relatively short. e determining factors are the sensitivity
of the x-ray lm to the type of light used and the position
and intensity of the light source. Usually, a
7
1
2
- to 10-W
bulb with a yellow lter (e.g., Kodak yellow Morlite M-2)
placed 3 to 4 feet from the work surface is used for working
with intraoral lm. If extraoral screen lm is used, a Kodak
GBX-2 Safelight Filter with a 15-W bulb is needed because
of the lms increased sensitivity to light. is lter also can
be used for intraoral lm. If both intraoral and extraoral
lm is being processed, an extraoral safelight (e.g., Kodak
GBX-2) is recommended, because it will be safe for both
intraoral and extraoral lm processing.
A simple and reliable way to check a safelight is by the
coin test, in which a coin is placed on an unwrapped,
unexposed piece of dental lm on a at surface under
safelight conditions. After 3 minutes of exposure to the
safelight, the lm is developed. If the lm shows an outline
of the coin, the light is not safe; the uncovered part of the
lm should have been as unaected as the part covered by
the coin (Fig. 11.2).
Cell Phones
e recent increase in the use of cell phones has produced
another possible source of light that could fog or completely
expose and ruin the lm. When the cell phone is on, it
produces light that aects the lm. is is more likely to
B
A
Figure 11.2 Coin test for safelighting. A, Coin placed on unex-
posed lm. B, Processed radiograph showing an outline of the coin,
indicating that the safelight is not safe.
happen with extraoral and panoramic lm, because they are
more sensitive to light and have a larger lm surface area.
However, the newer cell phones have a brighter light and
are apt to expose intraoral and extraoral lms. erefore,
it is advised that cell phones should not be on or actually
used in the darkroom.
Overhead White Light
e only requirement for overhead white light is that it must
provide adequate illumination for the size of the room. e
switch for this light should be placed either outside of the
darkroom or in a position inside of the darkroom where it
cannot be bumped accidentally and turned on, potentially
exposing lms to white light illumination.
Viewing Safelight
Some dental oces use wet readings or rapid processing
techniques especially for emergencies and working lms.
In these cases, it is convenient to have a viewing safelight
mounted on the wall behind the processing tanks. en,
lms can be removed from the xer after 3 minutes and
checked by safelight to see if they have cleared enough for
washing and reading.
X-Ray Viewbox
e ability to read wet lms in the darkroom is a great
convenience. A proper interpretation of the radiographs can
be made more adequately by having an acceptable viewing
mechanism in the darkroom. If there is adequate space in
the darkroom, it should have a viewbox to allow for proper
viewing of the radiographs after they are processed.
Outside Warning Light
is light should be wired so that when the safelight
is on in the darkroom, the warning light is on outside
the darkroom. is alerts members of the oce sta to
the presence of a colleague who is processing lm inside
the darkroom and helps to prevent entry into the darkroom
when safelight precautions are in eect.
Plumbing
e darkroom should have intake lines of hot and cold
water with an adequate drainage line. ere should be a
thermostatic valve controlling intake to maintain constant
temperatures of the solutions. e disposal line should be
made of materials that resist the action of the processing
chemicals. If automatic processors are used, the ow rate
of the incoming water should be considered in planning
darkroom plumbing. Automatic processors have individual
requirements for ow rates of water, which should be a
factor in darkroom planning and choosing an automatic
processor.
A sink with a gooseneck faucet is extremely convenient
for tank cleaning and solution changing. is is often
overlooked in darkroom planning; dental personnel will
realize that oversight the rst time they carry processing

125CHAPTER 11 Film Processing Techniques
Overflow
valve
Developer Fixer
Drain
Thermostat
Water
bath
Thermometer
C
o
l
d
w
a
t
e
r
H
o
t
w
a
t
e
r
Figure 11.3 Typical processing tanks in a dental ofce.
tanks to the nearest sink for cleaning and replenishing. e
gooseneck faucet is essential because a normal-size faucet
neck does not allow enough room to place the tanks under
the faucet for cleaning.
Contents
Processing Tanks
Most dental oces have processing units that contain either
1- or 2-gallon developer and xer insert tanks suspended
in a tank of running water (Fig. 11.3). e unit should be
made of stainless steel, and the water bath should have a
thermostatically controlled ow valve to keep the solutions
at the desired temperature. Each tank is equipped with a
lid that should be kept on at all times. e cover protects
developing lms from accidental exposure to white light
and prevents oxidation and evaporation of the processing
solutions.
Solutions
Table 11.1 lists the main ingredients of the developer and
xer solutions and their functions. e developer and xer
solutions used for manual processing are usually supplied
as liquid concentrate that must be diluted. Extra amounts
of prepared solutions should be stored in either dark bottles
or opaque plastic containers away from heat and light
sources.
Under normal working conditions, developer and xing
solutions should be changed at a minimum of every 2 to 3
weeks. A normal workload is considered to be 30 intraoral
lms per day. If an oce exceeds 30 intraoral lms per day
and/or processes many panoramic lms, solutions should be
changed more often. e chemical solutions lose strength
when exposed to air and should be replaced even if normal
workload maximums have not been met. Remember that
lm development is a chemical reaction: Every time the
developer and xer solutions aect a lm emulsion, the
solutions become weakened. Consequently, in a busy oce,
solutions may have to be changed more frequently. Weak
Ingredient Function
Developer
Elon or Metol and
hydroquinone
(developing agent)
Reduces the energized silver
bromide crystals to silver
Sodium sulte
(preservative)
Prevents oxidation of developer
Sodium carbonate
(activator)
Provides alkaline medium and
softens gelatin to allow
developing agents to reach
silver bromide crystals
Potassium bromide
(restrainer)
Controls activity of developing
agents and prevents
chemical fog
Fixer
Sodium thiosulfate
(clearing solution)
Removes undeveloped or
unexposed silver bromide
crystals from the emulsion
Sodium sulte
(preservative)
Prevents the decomposition of
the thiosulfate clearing agent
Potassium aluminum
sulfate (hardener)
Shrinks and hardens gelatin
Acetic acid (acidier) Maintains acid medium
Chemicals for Development Process
TABLE
11.1
developer and xing solutions do not bring out the optimum
image on the lm and thus do not provide the maximum
diagnostic information for the radiation exposure.
Replenishing
Developer and xer solutions should be replenished daily.
Commercially prepared replenishment solutions are avail-
able, but it is usually easier to use the standard developer

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12211 Film Processing TechniquesEDUCATIONAL OBJECTIVESUpon completing this chapter, the student will be able to:1. Dene the key terms listed at the beginning of the chapter.2. Explain the steps in manually processing dental lm.3. Describe the following related to the design and requirements of the darkroom:• Describewhatadarkroomisusedforandwhatthecomponents of an acceptable darkroom are.• Knowthetypesoflightingthatareinadarkroom.• Explainwhatasafelightisandwhatthecoin test is used for.• Discusstheplumbingofthedarkroom.• Discussthecontentsofthedarkroom,includingprocessingtanks,solutions,replenishingsolutions,timerandthermometer,lmhangers,anddryers.• Discussthesequenceformanualandautomaticprocessingandtherolesofthedeveloper,xer,andwater in both methods.4. Explainanddiscussthedevelopmentprocess, including:• Denethetermlatent image, and discuss how it is dierent from the visible image in dental lm processing.• Describetheproceduresformanualandautomaticprocessing.5. Describethetime-temperaturedevelopmentmethod,andcompare it to the sight development method.6. Explain the indication for use of rapid processing, and state what the components of this method are.7. State the importance of the care and maintenance of the darkroom and automatic processors and how they are included in a quality assurance program in dental facilities.8. Discuss the environmental concerns that are associated with lm processing.9. Knowwhatautomaticprocessingis,aswellasdescribethesteps involved in automatic processing.10. Knowthecommonprocessingerrorsformanualandautomatic processing and how to remedy each error.familiarity with the manual and automatic lm processing techniques continues to be included in dental radiology education. is chapter discusses manual and automatic processing, the components of a darkroom, the funda-mentals of processing, common processing errors, lm processing quality assurance, and environmental concerns in dental lm processing.IntroductionAlthough the use of digital radiographic techniques are on the rise in dental facilities, conventional lm-based radi-ography is still being used. While lm processing is slowly becoming a technique of the past, the basic knowledge and understanding of lm processing is still required in a thorough study of dental radiography. e fundamental KEY TERMSautomatic processingclear lmcoin testdark imagedarkroomdaylight loaderdense imagedeveloperdeveloper cutodrying rackelectrostatic artifactlm hangerlm rollerxergeneratorslatent imagelight leaklight-tightmanual processingoverdevelopedrapid processingreference lmreplenisherreticulationsafelightsight developmentstop baththermometerthermostatic valvethin imagetime-temperature techniquetorn emulsionunderdeveloped lmvisible imagewater bathwet reading 123CHAPTER 11 Film Processing Techniquesor both); and (4) the space required for duplicating, drying, and storage.e walls of the darkroom should be a light color that reects the safelighting; darkroom walls do not have to be black. e surfaces of the walls and oor should be of materials that are resistant to staining and can be cleaned of the processing solutions that inevitably spill or splash onto them.e darkroom must be completely light-tight so that when the safelight is on, it is the only illumination in the darkroom. Because x-ray lm is sensitive to white light, any light leaks can fog the lm. A fogged lm is less diag-nostic and in some cases may be useless. e easiest way to check for light leaks is to stand in the darkroom in com-plete darkness; any leaks around the door or in other areas will be apparent and should be corrected. e darkroom door should have an inside lock so that the door cannot be opened from the outside while lms are being processed. ere are also darkrooms with solid revolving doors to pro-hibit light from entering the room during processing as well.It is advised that the darkroom should be well ventilated to exhaust the moisture from the drying lms or the heat, if a dryer is used, and maintain comfortable working condi-tions. Keeping the darkroom at a reasonable temperature makes it easier to maintain desired processing solution tem-peratures. Another consideration to maintain lm quality is to avoid storing unexposed lm in the darkroom cabinets, because at high temperatures (greater than 90° F) the lms can experience lm fog.LightingA well-designed darkroom has ve dierent light sources: (1) an illuminating safelight, (2) an overhead white light, (3) a viewing safelight, (4) an x-ray viewbox, and (5) an outside warning light.Illuminating SafelightWhen lm packets are opened, lm is attached to hangers, or lm is being processed, safelight conditions must be maintained. As mentioned, white light darkens x-ray lm. Safelight is any illumination that does not aect the x-ray lm (Fig. 11.1). It is a low-intensity light composed of long wavelengths from the orange/red range of the spectrum. Manual Processinge processing of exposed x-ray lm (either manually or automatically) is an important step in the radiographic chain of events. It is at this point that a visible image is produced, from which a diagnosis can be made. e x-rays that have penetrated the hard and soft tissue in the patient’s mouth have created a latent image on the exposed x-ray lm. e processing of this lm converts the latent image to a visible diagnostic image.Manual processing can occur inside or outside of the darkroom. In the darkroom, manual processing is per-formed with the required armamentaria, including manual processing tanks, processing solutions, proper lighting, lm-holding hangers, a thermometer, and other needed equipment. It should be noted that with increased use of digital radiography, the need for a darkroom has become less necessary (see Chapter 15).e darkroom is a room in the dental oce set aside for radiographic processing. In addition to processing lm, the dental professional must keep the darkroom clean, change solutions regularly, keep accurate records of processed radiographs, and maintain a quality assurance program. It is important to realize that the processing of lms is vital in the production of the diagnostic radiograph. Errors in the darkroom can easily ruin what would otherwise have been diagnostic radiographs, making it necessary to retake the lms with the resultant loss of time and increased radia-tion exposure to the patient. It is important to remember that every lm that requires retaking doubles the patient’s radiation exposure for that lm. An acceptable chairside radiographic technique must be coupled with an equally acceptable processing technique. e importance of elimi-nating darkroom errors should be uppermost in the minds of dental professionals.Design and Requirements of the Darkroome essential requirements and components of a darkroom that is used for manual processing are that it should be light-tight and have safelight and white light illumination, processing tanks, a thermostatically controlled supply of water, thermometer, timer, lm hangers, drying racks, and storage space.Location and Sizee darkroom should be a space unto itself, located near the rooms in which the x-ray units are placed. e darkroom should be a minimum of 16 square feet (4 × 4), allowing enough room for one person to work comfortably. e factors that should be considered in determining the space needed are (1) the volume of radiographs to be processed; (2) the number of dental professionals handling the processing; (3) the type of processing to be done (manual, automatic, • Figure 11.1 A variety of safelights are available for use in the darkroom including safelights now available in LED format for intraoral and extraoral lms. (Courtesy Carestream Health, Rochester, NY.) 124 CHAPTER 11 Film Processing TechniquesAs shown in Chapter 4 in the discussion of intensifying screens, x-ray lms are more sensitive to the blue/green region of the light spectrum, where the wavelengths are relatively short. e determining factors are the sensitivity of the x-ray lm to the type of light used and the position and intensity of the light source. Usually, a 712- to 10-W bulb with a yellow lter (e.g., Kodak yellow Morlite M-2) placed 3 to 4 feet from the work surface is used for working with intraoral lm. If extraoral screen lm is used, a Kodak GBX-2 Safelight Filter with a 15-W bulb is needed because of the lm’s increased sensitivity to light. is lter also can be used for intraoral lm. If both intraoral and extraoral lm is being processed, an extraoral safelight (e.g., Kodak GBX-2) is recommended, because it will be safe for both intraoral and extraoral lm processing.A simple and reliable way to check a safelight is by the coin test, in which a coin is placed on an unwrapped, unexposed piece of dental lm on a at surface under safelight conditions. After 3 minutes of exposure to the safelight, the lm is developed. If the lm shows an outline of the coin, the light is not safe; the uncovered part of the lm should have been as unaected as the part covered by the coin (Fig. 11.2).Cell Phonese recent increase in the use of cell phones has produced another possible source of light that could fog or completely expose and ruin the lm. When the cell phone is on, it produces light that aects the lm. is is more likely to BA• Figure 11.2 Coin test for safelighting. A, Coin placed on unex-posed lm. B, Processed radiograph showing an outline of the coin, indicating that the safelight is not safe. happen with extraoral and panoramic lm, because they are more sensitive to light and have a larger lm surface area. However, the newer cell phones have a brighter light and are apt to expose intraoral and extraoral lms. erefore, it is advised that cell phones should not be on or actually used in the darkroom.Overhead White Lighte only requirement for overhead white light is that it must provide adequate illumination for the size of the room. e switch for this light should be placed either outside of the darkroom or in a position inside of the darkroom where it cannot be bumped accidentally and turned on, potentially exposing lms to white light illumination.Viewing SafelightSome dental oces use wet readings or rapid processing techniques especially for emergencies and working lms. In these cases, it is convenient to have a viewing safelight mounted on the wall behind the processing tanks. en, lms can be removed from the xer after 3 minutes and checked by safelight to see if they have cleared enough for washing and reading.X-Ray Viewboxe ability to read wet lms in the darkroom is a great convenience. A proper interpretation of the radiographs can be made more adequately by having an acceptable viewing mechanism in the darkroom. If there is adequate space in the darkroom, it should have a viewbox to allow for proper viewing of the radiographs after they are processed.Outside Warning Lightis light should be wired so that when the safelight is on in the darkroom, the warning light is on outside the darkroom. is alerts members of the oce sta to the presence of a colleague who is processing lm inside the darkroom and helps to prevent entry into the darkroom when safelight precautions are in eect.Plumbinge darkroom should have intake lines of hot and cold water with an adequate drainage line. ere should be a thermostatic valve controlling intake to maintain constant temperatures of the solutions. e disposal line should be made of materials that resist the action of the processing chemicals. If automatic processors are used, the ow rate of the incoming water should be considered in planning darkroom plumbing. Automatic processors have individual requirements for ow rates of water, which should be a factor in darkroom planning and choosing an automatic processor.A sink with a gooseneck faucet is extremely convenient for tank cleaning and solution changing. is is often overlooked in darkroom planning; dental personnel will realize that oversight the rst time they carry processing 125CHAPTER 11 Film Processing TechniquesOverflowvalveDeveloper FixerDrainThermostatWaterbathThermometerColdwaterHotwater• Figure 11.3 Typical processing tanks in a dental ofce. tanks to the nearest sink for cleaning and replenishing. e gooseneck faucet is essential because a normal-size faucet neck does not allow enough room to place the tanks under the faucet for cleaning.ContentsProcessing TanksMost dental oces have processing units that contain either 1- or 2-gallon developer and xer insert tanks suspended in a tank of running water (Fig. 11.3). e unit should be made of stainless steel, and the water bath should have a thermostatically controlled ow valve to keep the solutions at the desired temperature. Each tank is equipped with a lid that should be kept on at all times. e cover protects developing lms from accidental exposure to white light and prevents oxidation and evaporation of the processing solutions.SolutionsTable 11.1 lists the main ingredients of the developer and xer solutions and their functions. e developer and xer solutions used for manual processing are usually supplied as liquid concentrate that must be diluted. Extra amounts of prepared solutions should be stored in either dark bottles or opaque plastic containers away from heat and light sources.Under normal working conditions, developer and xing solutions should be changed at a minimum of every 2 to 3 weeks. A normal workload is considered to be 30 intraoral lms per day. If an oce exceeds 30 intraoral lms per day and/or processes many panoramic lms, solutions should be changed more often. e chemical solutions lose strength when exposed to air and should be replaced even if normal workload maximums have not been met. Remember that lm development is a chemical reaction: Every time the developer and xer solutions aect a lm emulsion, the solutions become weakened. Consequently, in a busy oce, solutions may have to be changed more frequently. Weak Ingredient FunctionDeveloperElon or Metol and hydroquinone (developing agent)Reduces the energized silver bromide crystals to silverSodium sulte (preservative)Prevents oxidation of developerSodium carbonate (activator)Provides alkaline medium and softens gelatin to allow developing agents to reach silver bromide crystalsPotassium bromide (restrainer)Controls activity of developing agents and prevents chemical fogFixerSodium thiosulfate (clearing solution)Removes undeveloped or unexposed silver bromide crystals from the emulsionSodium sulte (preservative)Prevents the decomposition of the thiosulfate clearing agentPotassium aluminum sulfate (hardener)Shrinks and hardens gelatinAcetic acid (acidier) Maintains acid mediumChemicals for Development ProcessTABLE 11.1 developer and xing solutions do not bring out the optimum image on the lm and thus do not provide the maximum diagnostic information for the radiation exposure.ReplenishingDeveloper and xer solutions should be replenished daily. Commercially prepared replenishment solutions are avail-able, but it is usually easier to use the standard developer 126 CHAPTER 11 Film Processing TechniquesManual Processing: Time and Temperature Chart80° F 212 minutes in the developer75° F 3 minutes in the developer70° F 4 minutes in the developer (optimum)68° F 412 minutes in the developer60° F 6 minutes in the developerFilm HangersFilm hangers come in various sizes and contain clips for 2 to 20 lms. In all cases, the lms should be unwrapped and attached to the clips (Fig. 11.5). It is important that the lm not be touched with contaminated gloves or ungloved hands. e working surface on which the hanger is loaded should be clean and dry to prevent lm staining. Film hangers should be labeled to avoid mix-ups. Hangers with defective clips should be discarded, because a defective clip can scratch lms on adjacent hangers in the solution. Defective clips may also lead to lost lms in the solutions.DryerAfter lms have been washed for 20 to 30 minutes, they are ready for drying. is can be accomplished with the use of an x-ray dryer or simply by hanging them on towel racks in the darkroom and letting the lms air dry. In either method, the lms should not touch one another or they will stick together; separating them will tear the emulsion. Drying racks should be in a clean area.The Development ProcessExplanation and DiscussionLatent ImageRadiographs after having been exposed are said to contain a latent image. e silver halide on the radiographic emulsion is energized by the x-ray beam. e pattern of the energized silver halide crystals depends on the densities of the objects being radiographed. For instance, the silver halide crystals on the lm that lie behind a metallic restoration receive almost no radiation, because the density of the metal absorbs and xer solutions to ll the tanks. Approximately 8 oz of replenishment are required each day for the developer and xer solutions. Commercial replenishers include manufac-turer’s instructions. e replenisher is added directly to the existing solutions in their respective tanks to bring them to the proper uid levels. e levels of solutions always should be kept at the top of the tank to ensure that all immersed lms are completely covered with solution. Water should never be added to the solutions to bring them to tank-top level; this dilutes the strength of the chemicals.Timer and ThermometerA darkroom is not complete without a timing device and a thermometer (Fig. 11.4). Even with the most modern radio-graphic equipment, optimum results will not be produced without time and temperature control in the darkroom. e timer is used to determine the length of time the lms stay in the developer solution. is is solely dependent on the temperature of the developer. To determine the temperature of the developer, a thermometer must be suspended in the developer solution. Each day, it may take some time for equalization of temperatures between the water tank and the developer tank. For this reason, the temperature of the developer bath is read, not the temperature of the water entering the surrounding water tank. ese charts may vary slightly from manufacturer to manufacturer. A time-temperature chart like the following chart should be referenced when manually processing lms.BA• Figure 11.4 Darkroom timer (A) and thermometer (B). Both are essential parts of the time-temperature technique. (Courtesy Flow Dental, Deer Park, NY.)• Figure 11.5 Placing lm on hangers in the darkroom under safe-light conditions. 127CHAPTER 11 Film Processing Techniquesis precipitation corresponds to the black (radiolucent) areas on the radiograph. An area of less density, such as the pulp, allows greater penetration of x-rays; therefore, more x-rays reach that part of the lm. e silver halide crystals are more greatly energized, and more silver precipitates to give a black, or radiolucent, outline to the pulp chamber when compared to the dense areas that correspond to the radiopaque areas on the radiographic image (Fig. 11.6).is is a chemical reaction. e optimum precipita-tion of silver for the amount of x-ray energy delivered to the object takes place in a specied amount of time with the developing solution at a certain temperature. is is the basis and importance of the time-temperature technique.If lms are left in the developing solution too long, more silver precipitates than was intended, and dense and all the x-ray energy. Silver halide crystals on the lm that correspond to an area (such as, the pulp of the tooth or a cavity) receive more radiation energy, because these areas are less dense and absorb little x-ray energy.DevelopingExposed dental lm packets should be processed as soon as possible. In the darkroom under safelight conditions, the x-ray lms are removed from the packets and placed on lm racks. e developer is the rst solution into which these lm racks are placed. e developer has a pH above 7 and thus is a “basic” solution as compared with the “acidic” xing solution. e developer softens the gelatin and allows the solution to chemically reduce the energized silver halide crystals by precipitating silver on the lm base. Latent image;energized crystalsare shaded grayStart of development;energized crystals areprecipitated as free silver(black areas)Development complete;completely energizedsilver precipitated asblack areasFixer removes unaffectedcrystals, leaving black,white, and gray areas1234Metallic fillingPulpCariesDentinEnamelAir• Figure 11.6 X-ray lm development. 128 CHAPTER 11 Film Processing TechniquesPROCEDURE 11.1 MANUAL PROCESSING1. Lock the darkroom door from the inside, and label the lm hanger.2. Stir the solutions to equalize the temperature and the chemical distribution of the processing solutions. Use a different utensil for stirring each solution to prevent cross-contamination of the solutions. Check the levels of solutions and replenish if necessary.3. Check the temperature of the developing solution and set the timer. Refer to the time-temperature chart, which should be accessible when processing, and set the time for the desired interval.4. Turn off the white light, and turn on the safelight.5. Put on gloves and open the lm packets while dropping the lms on a clean working surface if barrier envelopes were not used while exposing the lms. If barrier envelopes were used while exposing the lms, then clean, dry, ungloved hands may be used to handle the lms. When applicable, discard contaminated lm packets and/or barrier wraps, remove gloves, and load the lm hangers. Work carefully, avoiding nger marks or lm scratches. Be sure that the lm is securely fastened to lm hanger clips.6. Immerse the lm hanger in the developer solution and activate the timer. After immersing the lm, immediately raise and lower the hanger slowly a few times so that the lm surfaces are covered totally by solution.7. Remove the lm rack from the developer when the timer sounds (under safelight conditions).8. Rinse thoroughly for 20 seconds in the water bath (under safelight conditions).9. Place the lm rack in the xer solution. Gently agitate the rack up and down immediately after the initial placement. Films should remain in the xer for a minimum of 10 minutes (approximately twice the developer time) for permanent xation but may be removed after 3 or 4 minutes for use as a wet reading. After xing, with the tank lids rmly in place, normal lighting can be resumed in the darkroom. Safelighting is not needed after the timer signals that xation is complete and lms are moved from the xer to the water bath.10. Place the lms in the running water bath for 20 minutes.11. Dry the lms. Remove the lms from the water bath and suspend them from rack holders or place them in a lm dryer to dry. HELPFUL HINTWhile the lm is in the developer, it is preferable for you to remain in the darkroom. If necessary, you can leave the darkroom, but be sure to check that the tank lids are securely in place before you leave.PROCEDURE 11.2 AUTOMATIC PROCESSING1. If there is no daylight loader on the automatic processor, lock the darkroom door, and make sure to keep a record of the name of the patient whose lms are to be processed.2. Turn on the processor or switch from the standby to the ready mode.3. Turn off the white light, and turn on the safelight.4. Put on gloves and open the lm packets while dropping the lms on a clean working surface on the automatic processor if barrier envelopes were not used while exposing the lms. If barrier envelopes were used while exposing the lms, then clean, dry, ungloved hands may be used to handle the lms. When applicable, discard contaminated lm and/or barrier wraps, remove gloves, and load the lm into the processor. Be sure that the lms are aligned with the lm tracks and that they are not put in so quickly as to produce overlapping of the lms during processing.5. Retrieve the dried lms, and place them in a mount. HELPFUL HINTWhen loading lm into the automatic processor, it is a good idea to alternate tracks to avoid the lms overlapping and sticking together.less dense structures lose their distinctions. A completely overdeveloped lm results when all the silver is precipitated by the developer and the lm is totally black.Crystals of silver halide that have received small amounts of radiation have correspondingly less silver precipitated and appear gray. e silver halide that was not energized by radiation, such as the area on the lm behind a gold crown, precipitates no silver and appears white, or radiopaque, on the x-ray lm.Rinsing (Stop Bath)e main purpose of this step is to rinse the lm to remove the developer from the lm so that the development process stops. is step is similar to photographic developing of the past when a chemical stop bath was used to stop the developing and also remove the “basic” developer so that it does not contaminate the “acidic” xer.In dental radiography, this is usually accomplished by agitating the lm hanger in a water bath for about 20 seconds. Safelight conditions must be maintained when the lms are transferred from the developer to the wash tank and then to the xing solution.Fixinge acidic xing solution (xer) removes the unexposed and undeveloped (unaected) silver halide crystals from the lm emulsion and rehardens the emulsion, which has softened during the development process. For permanent xation, the lm is kept in the xing solution for a minimum of 10 minutes. However, lms may be removed from the xing 129CHAPTER 11 Film Processing Techniquessolution after 3 minutes for viewing. is procedure is known as the wet reading and is useful when lms are needed immediately. For example, a wet reading of a lm would be used to check that all of the root tip has been removed in an extraction before dismissing the patient. As previously mentioned, a lm is ready for a wet reading if it has cleared enough for washing and reading. Operators should always check for clearance or the lack of murkiness under safelight conditions.Because all lms should be made part of the patient’s permanent record (archival), they should be returned to the xing solution to complete the required 10 minutes. Films not xed properly fade and turn brown in a short time. Excessive xing (i.e., 2–3 days) can completely remove the image from the lm.Washing and Dryinge lm is washed for about 20 minutes in the water tank to completely remove the xing solution from the emulsion. e lm is then dried in a clean, dust-free area. Be aware that excessive washing that continues for 24 to 48 hours will remove the image from the lm and should be avoided.Time-Temperature Versus Sight Developmente best way to manually process dental x-ray lms is by the time-temperature development method, as described in this chapter. is scientic method produces optimum information on the lm. Even so, many dental oces develop x-ray lms by using sight development. e usual technique is to immerse the lm hanger in the developer, removing it at frequent intervals to hold it up to the safelight, until llings or root shapes are visible. At that point, the lms are washed and placed in the xer. is is obviously an inexact, unacceptable technique. Sight development is ultimately unfair to the patient, because it does not provide the maximum diagnostic information for the radiation exposure. e time-temperature method, performed either manually or by automatic processors, is the most acceptable and standardized way to process dental radiographs.Rapid ProcessingRapid processing of dental radiographs is done with the use of higher-solution temperatures, concentrated solu-tions, agitation of the lm, or a combination of these. It is sometimes called hot processing, which is a term that refers to the temperature of the solutions. Rapid processing does not require an increase in radiation to the patient, but the images produced by this technique are not comparable in density and denition to lms processed by standard methods. e use of rapid processing is clinically indicated when time is more important than exacting detail of the image. For example, it may be used when a patient has just had an extraction and a radiograph is taken to make sure that no debris is left in the socket before suturing. Working or operative endodontic radiographs can also be processed with this method. Rapid processing can be helpful with endodontic working lms and postoperative lms in oral surgery when a high degree of denition is not essential. It should not be used for routine processing of lms.e use of regular-strength developing solutions at 92° F with agitation of the lm can produce acceptable diagnostic images in less than 1 minute (20 seconds developing, 3 seconds washing, and 30 seconds xing). Concentrated processing solutions are also available that can be used at room temperature. e increased chemical activity of these solutions makes the rapid processing possible. Some of these solutions use a two-bath technique—developer and xer; others use a single-bath technique, or monobath, that contains the developer and the xer (Fig. 11.7).Extraoral and Panoramic FilmsExtraoral and panoramic lms are processed in the same manner as intraoral lms, using the time-temperature technique with the same solutions. As mentioned, the only precaution that must be taken is to check safelight intensity. ose extraoral lms that are used in combination with intensifying screens (screen lms) are more sensitive to light than nonscreen lms. Darkroom illumination that may be safe for intraoral lms may adversely aect screen lms. e safety of the light can be checked by using the coin test discussed earlier in this chapter.Care and Maintenance of the DarkroomDarkroom maintenance is a means of ensuring quality control. Maintenance should be likened to our regard for sterility to avoid contamination and subsequent infection. Contaminants in the darkroom or other errors resulting from sloppy techniques may ruin diagnostic radiographs and require retaking of lms, which leads to an unnecessary increase in the patient’s radiation burden.• Figure 11.7 Concentrated solutions of lm developer and xer. (Courtesy Carestream Health, Inc, Rochester, NY.) 130 CHAPTER 11 Film Processing Techniquesthe darkroom viewbox. When the processed lms start to show a thin image, the solutions should be changed even if it is before the scheduled change date.e lids of the processing tanks always should be closed when the tanks are not in use to prevent oxidation and weakening of the solutions.Record KeepingTwo types of records are important in the darkroom. e rst is the supply inventory, including the date of the next scheduled solution change. It is helpful to post the date of the next scheduled solution change in a prominent place.Film identications are the second important type of records in the darkroom; accurate records are essential to processing radiographs. e patient’s name, chart number (if applicable), the number of lms, the number or letter of the hanger on which the lms were placed, and the date should be recorded. is eliminates the likelihood of lost lms or mixed radiographs.Environmental ConcernsDental professionals must be aware of and comply with a growing number of environmental laws that regulate the management of waste materials. It is our professional responsibility to be aware of these federal and local regula-tions as they apply to our oce and to comply.Dental radiology generates the following three types of waste: (1) solid waste, (2) x-ray processing solution euent, and (3) medical waste. Solid waste is the x-ray lm packaging, including the lead foil but not the outside packet wrapping. e euent is the liquid waste coming from the x-ray processing chemicals. e medical waste consists of only the intraoral dental packets that have been contaminated by blood or blood components and saliva.e federal statute that regulates discarded material is the Resource Recovery Act of 1976. Professionals who create hazardous wastes are referred to in this statute as generators. Most dental oces in the United States would be classied as “conditionally exempt small-quantity Cleanlinesse working surface, where lm packets are opened and the lms are placed on hangers, always should be clean and dry. Developer, xer, and water produce the most common stains. Drying lms should not be placed above the working surface without a surface protector under them. If the working surface is made of Formica, it can be cleaned easily with a mild detergent. Film hangers should be clean and dry when lms are loaded. Hangers used for wet readings are the most likely ones to be insuciently washed and can contain residual xer that can stain the next lm. Hangers should be washed after each use and clean, and dry hangers should always be used.Processing tanks should be cleaned thoroughly when solutions are changed. is includes not only the insert tanks that hold the developer and xer, but also the water reservoir. e water tank may accumulate sludge and algae, especially under the metallic lip and in the overow tube. Operators can use a bland detergent or preferably one of the tank cleaners made specically for this purpose. It is in this routine tank cleaning that one can appreciate a deep sink and a gooseneck faucet in the darkroom.SolutionsSolutions should be brought to the optimal temperature at the beginning of the working day and kept at that tem-perature by the thermostatic control on the mixing valve.Tanks should be kept full by the use of replenishers rather than by the addition of water, because water dilutes the concentration and weakens the solutions. If the tanks are not kept full, the lms or portions of the lms on the top clips of the lm rack may not be immersed fully in solution and will not be developed (Fig. 11.8).As mentioned earlier, both the developer and xer solu-tions should be changed at least every 2 to 3 weeks. In practices with heavy lm volume, it may be necessary to change solutions as often as once a week. Processed lms should always be compared with a reference lm (Fig. 11.9) of desired density and contrast that is kept posted on • Figure 11.8 Low solution levels. • Figure 11.9 Processed lm being compared with a reference lm. 131CHAPTER 11 Film Processing Techniquesgenerators,” because the small amount of hazardous waste that they generate is exempt from federal regulations. State and local laws vary, and exemption from federal regulation does not mean automatic exemption from local laws. Under most local laws, the hazardous waste must be removed by a certied carrier (in red bags) in the same way that used gauze pads or cotton rolls are removed. Large dental clinics and dental schools, because of their volume, may be classied as “small-quantity generators” and may be subject to federal regulation.Silverere are two sources of silver retrieval in the dental oce. In the category of solid waste are the old, no longer needed, or unusable processed radiographs. e second source is the exhausted xer solution, which falls under the euent category.Silver can be recovered from the processed radiographs by ashing the lm above the melting point of silver. Ashing is an environmentally sound practice and is preferred to ordinary disposal. Discarded lm is generally not a regulated waste. e discharge of xer processing solution euent into a sewer system or a septic tank is not recommended and in many localities is prohibited by law, depending on the concentration of silver in the euent. e concentra-tion depends on the volume of lms processed. Chemical precipitation or electrolysis can retrieve residual silver from the xer and the wash water. ere is no residual silver in developer solution; thus, it can be discharged into the sewage system (Fig. 11.10). Exhausted silver solutions can be removed by a certied carrier.rowing the lead foil inserts of lm packets in regular trash is not environmentally sound; although there is very little lead in each packet, the total amount of lead entering the environment because of the discarding is signicant. ere are cardboard holding boxes for collecting and ship-ping the foil to qualied disposal facilities.Medical waste must be removed by a certied carrier in the same manner as for disposal of used gauze pads, cotton rolls, and so on.Automatic ProcessingAutomatic dental x-ray lm processing is currently more popular than manual processing in dental facilities that are still using conventional lm for radiographic exposures. e major advantage of automatic processing is the maintenance of standardized procedure; these units provide solutions of proper strength, correct temperature, and regulated processing time. In short, they provide automated time-temperature processing. Other advantages of the units are the time saved and the increased volume of lms that can be processed when compared with the manual method. ese units also require maintenance and a quality-control program.e typical automatic processor has three solutions—developer, xer, and water—and have a built-in drying chamber (Fig. 11.11). e wash between developer and • Figure 11.10 Cartridges allow for recovery of silver from photo-graphic solutions. (Courtesy Carestream Health, Inc, Rochester, NY.)Daylight loaderDrying elementFilmFilmDevelopingsolutionFixingsolutionWaterwashDryingelementFilmexit• Figure 11.11 Automatic lm processor. 132 CHAPTER 11 Film Processing Techniquesxer solution is eliminated in most automatic processors. A transport system of either rollers or tracks driven by gears, belts, or chains moves the lm from solution to solution and then into the drying chamber. Finished lm is produced in 4 to 7 minutes; some units have the capacity to process even faster by elevating the temperature of the solutions.Automatic processors vary in the size of lm that they can accept, their safelight and plumbing requirements, and the option of automatic replenishment. Freestanding units are not connected to water and waste lines and may be kept in the operatory, as lms are fed into the unit through a daylight loader.Size of FilmSome units accept only periapical and bitewing size lm (#0, #1, #2, and #3; Fig. 11.12), whereas others can accom-modate all sizes, including 8 × 10-, 5 × 12-, or 6 × 12-inch panoramic lm (see Fig. 11.12).SafelightSome processors must be located in the darkroom, because safelight procedures are required for opening and inserting the lm into the automatic processor (Fig. 11.13). Units with daylight loaders do not have to be in the darkroom, because they have light-tight baes into which the hands are placed while opening the lm packet and inserting the lm into the rollers (Fig. 11.14). e problems of infection control with daylight loaders were discussed previously in Chapter 8.PlumbingIf there is a constant ow of water in the wash chamber, plumbing is required to bring in the water and a waste line for recapturing the xer to remove the silver. is arrange-ment can be more desirable than a freestanding chamber, in which the water level may drop and constant change is necessary.Automatic ReplenishmentMore sophisticated processors maintain solution concentra-tion and levels by automatic replenishment. Each time a piece of lm is fed into the unit, a few drops of xer and developer are added automatically to the baths to maintain solution strength.Care and MaintenanceAutomatic processors require daily or weekly cleaning, depending on the volume of lms processed. e lm rollers should be cleaned at the beginning of the day by running an extraoral size lm or clean-up lm that is designed to clean through the rollers. is removes any residual debris or dirt from the rollers. e rollers should be • Figure 11.12 Automatic processor that could accommodate panoramic-sized lm. (Courtesy Air Techniques, Inc., Melville, NY.)• Figure 11.13 Film being inserted into an automatic processor in the darkroom under safelight conditions. (From Langlais RP, Miller CS: Exercises in Oral Radiology and Interpretation, ed 5, St Louis, 2017, Elsevier.)• Figure 11.14 Daylight loader of an automatic processor being loaded outside the darkroom. (From Langlais RP, Miller CS: Exercises in Oral Radiology and Interpretation, ed 5, St Louis, 2017, Elsevier.) 133CHAPTER 11 Film Processing Techniqueslm. Carelessness in feeding the lms too quickly may lead to the lms overlapping in the automatic processor.Quality assurance for processing is also discussed in a later chapter.Duplicate RadiographsAfter the exposure to light in the duplicating device, dupli-cate radiographs (see Chapter 4) are processed in the same manner, either manually or automatically, as other lms are processed.COMMON ERROR 11.1 THE DARKROOM (see also the Appendix)Fogged Film (Fig. 11.15). A fogged lm has an overall gray appearance because of diminished contrast. This can be caused by light leaks in the darkroom, cell phone light exposure, improper safelighting, or improper lm storage, as well as exposure to scatter (secondary) radiation.Remedy. Safelight conditions can be checked with a coin test (see Fig. 11.2). All doors should be checked for possible leaks, unexposed and exposed lm should be kept away from scatter radiation, cell phones should be off or not brought into the darkroom, and old lm should be used rst.Underdeveloped Film: Thin Image (Fig. 11.16). Underdeveloped lm is light (thin) in appearance and does not contain all possible diagnostic information. This results when the optimum amount of silver has not been precipitated because of weak or cold developing solutions or insufcient developing time. This type of lm is identical to the thin image produced by such chairside technique errors as incorrect time setting or increased focal lm distance (underexposed image).Remedy. The developer and xing solutions should be changed every 2 to 3 weeks, and the time-temperature method should be used. That is, the temperature of the developer should be checked before lms are immersed in the solution, and the timer should be set for the appropriate time. This error can also occur with sight developing and can be avoided by using the time-temperature processing technique. Daily quality assurance checks should be performed to determine solution strength.Overdeveloped Film: Dense Image (Fig. 11.17). Overdeveloped lm may vary from dark to totally black depending on the degree of overdevelopment. This type of lm is of no diagnostic value. A dense image, or dark image, results when too much silver has been precipitated on the lm base; in the case of the totally black lm, all the silver from the silver bromide has been precipitated. This error can be caused by hot developing solutions or prolonged developing time. As mentioned with light lms, chairside errors—including setting the exposure time incorrectly—can produce an overexposed image that is similar in appearance to an overdeveloped lm.Remedy. The time-temperature method of processing should always be used. The timer should have a bell or buzzer that rings when the developing time has elapsed. This enables the dental professional to leave the darkroom while the lms are being processed. Without the bell, the dental professional may be distracted by other duties and forget to remove the NOTEIt is important to store lms according to their expiration dates. We recommend the FIFO method. FIFO stands for rst-in, rst-out, meaning that the lms that will expire rst should be stored in the front of the storage area so that they are used rst and do not expire before they are used.Text continued on p. 138• Figure 11.15 Maxillary molar radiograph that has been fogged. Note lack of denition and contrast. • Figure 11.16 Underdeveloped lm. removed weekly from the processor and soaked in a water bath for about 20 minutes.Solution levels should be checked at the beginning of every day and replenished when necessary. Quality-assurance checks are also necessary. e processors are only as good as the care that their operators give them.Technique remains important and cannot be neglected just because the machine runs automatically. Films should not be fed into the rollers too quickly. Operators should maintain at least a 10-second interval between lms on the same track. is prevents overlapping of lms in processing and failure of chemicals to reach overlapped portions of the Continued 134 CHAPTER 11 Film Processing Techniqueslms from the developer at the proper time. This error can also occur with sight developing and can be avoided by using the time-temperature processing technique. Operators should perform daily quality assurance checks on solution strength as well.Developer Cutoff (Fig. 11.18). Films with developer cutoff show a straight radiopaque border on what was the upper edge of the top lm on the processing hanger. This is an undeveloped area of the lm. When the solutions are allowed to deplete in the processing tanks, the lms on the top positions on the racks may not be covered by solution when the racks are placed in the tanks. This error should be differentiated from collimator cutoff with a circular column, which results in a curved radiopaque border. In collimator cutoff, the lm portion is unexposed; in developer cutoff, the lm portion is undeveloped. However, developer cutoff is similar in appearance to collimator cutoff with a rectangular column; it is recommended for operators to retrace their steps when trying to investigate if the error was caused during exposure or processing.Remedy. One should always make sure that processing tanks are full. If the levels of solutions have dropped, water should not be added; this only dilutes the solution and results in underdeveloped lms. Proper replenisher solutions should be added to maintain the desired level.Clear Films (Fig. 11.19). Films are clear because the entire emulsion has been washed off. This occurs when lms are left in the xer or running water baths for 24 to 48 hours. Clear lms due to a processing error are identical in appearance, but not in cause, to unexposed lm that is developed and processed. With unexposed lm, the xer removes all the unaffected silver bromide crystals. Clear lms can also result if a lm is placed in the xer solution before the developing solution.Remedy. Films should never be left in water baths overnight. Processing should be complete before one leaves the ofce. Films should not be left in the xer overnight or for prolonged periods beyond the recommended 10 minutes; the xer will lighten and ultimately remove the image. Do not place exposed lms in the xer before the developer.Stained Films (Fig. 11.20). If the working surface in the darkroom is wet and dirty, lms can be stained either before or after processing. Stains caused by the developing solution are dark; and if they are caused by the xer solution, they are light.Remedy. Darkroom work surfaces must be kept clean and dry.Discolored Films (Fig. 11.21). Films that have not had adequate xation (approximately twice the developing time) COMMON ERROR 11.1 THE DARKROOM (SEE ALSO THE APPENDIX)—cont’d• Figure 11.17 Overdeveloped lm. BA• Figure 11.18 Radiographs with developer cutoff. • Figure 11.19 Clear lm can result from excessive washing or xing or an unexposed lm. 135CHAPTER 11 Film Processing TechniquesContinuedturn brown after a period and are useless as part of the patient’s permanent record. A radiograph should have an archival life of at least 7 years.Remedy. All lms must have adequate xation time (10 minutes). All wet readings should be returned to the xing solution after the patient has been treated for optimum xing.Torn Emulsion (Fig. 11.22). If lms that are drying are allowed to touch and overlap, they stick together, leading to a torn emulsion. When one separates the lms by tearing them apart, the emulsions are usually torn off the lm base in the overlapped area, rendering the lm useless for diagnosis.Remedy. Film racks should be checked to ensure that drying lms from different racks are not touching. If there are lms stuck together, it is recommended to wet those lms with water and gently separate them from each other.Scratched Films (Fig. 11.23). A radiopaque line on a lm is usually an artifact caused by scratching the emulsion on the lm base in lm processing. Most often, it is the result of putting a second lm rack into a tank that already contains a lm rack. It also can be caused by ngernails scratching the lm while it is being unpacked and placed on a rack, or it can be scratched by a broken clip on a lm rack.Remedy. When lm racks are put into the processing solution, care should be taken to avoid touching those already immersed. Any lm racks should be discarded if they have sharp edges or broken clips that could scratch other lms.COMMON ERROR 11.1 THE DARKROOM (see also the Appendix)—cont’d• Figure 11.21 Insufcient xing results in a partially discolored lm. BA• Figure 11.20 Stained radiographs. • Figure 11.22 Radiograph with torn emulsion. • Figure 11.23 Scratched radiograph. 136 CHAPTER 11 Film Processing TechniquesLost Film In Tanks. If lms are not rmly clipped onto the hangers, they may fall off in any of the three processing baths. A lost lm could necessitate a retake.Remedy. All lms should be checked to see that they are clipped securely to the hangers before processing.Fluoride Artifacts (Fig. 11.24). Some uorides, especially stannous uoride, produce black marks on radiographs.Remedy. After working with uoride, the dental professional should wash hands thoroughly with an appropriate cleanser or change gloves before handling lms in the darkroom.Reticulation (Fig. 11.25). If lm is developed at an elevated temperature and then placed in a cold water bath (or vice versa), the sudden change in temperature causes the swollen emulsion to shrink rapidly and give the image a wrinkled appearance called reticulation.Remedy. Sharp contrasts in temperatures between processing and the water bath should be avoided.Air Bubbles (Fig. 11.26). If air bubbles are trapped on the lm as it is placed in the processing solutions, the chemicals cannot affect the emulsion in that area.Remedy. The lm hangers always should be gently raised and lowered when they are placed in the processing solutions to coat the lms with solution. Aggressive agitation can cause air bubbles to stick to the lms.Static Marks (Fig. 11.27). Static electricity can be produced when intraoral lm packets are opened forcefully in the darkroom. This is not a common occurrence with intraoral lms. The same effect occurs much more often on extraoral lms. With these lms, static electricity may result when the piece of lm is removed from a full box; the sliding of the lm out of the tightly packed box may produce static electricity. Static electricity also may be produced during loading and unloading of cassettes in panoramic machines as the lm is slid in or out between the intensifying screens. In addition, walking around a carpeted ofce may produce static electricity. If the dental professional does not touch a conductive object before unwrapping the lm, electrostatic artifacts may result on the lm. Static electricity occurs most often on cold, dry days.Remedy. Operators should ground themselves by touching any conductive object in the darkroom before handling lm and should avoid friction of any kind against the lm that will produce static electricity especially on cold, dry days.COMMON ERROR 11.1 THE DARKROOM (see also the Appendix)—cont’d• Figure 11.24 Fluoride artifact. Operator’s ngertip, contaminated by uoride, touched lm during stripping and placing of lm on hanger. • Figure 11.25 Reticulation. • Figure 11.26 Artifact caused by air bubbles trapped on the lm, preventing processing solution from touching lm in the area. • Figure 11.27 Periapical radiograph with static marks. 137CHAPTER 11 Film Processing TechniquesAutomatic ProcessingDaylight Loaders: Light Leaks (Fig. 11.28). Film fog, a ruined lm, or unusual artifacts can be caused by removing one’s hands from the bafe (see Fig. 11.14) before the lm has entered the processor.Remedy. The operator’s hands must be kept on the lm until it has been completely taken up by the rollers. The material that makes up the bafe should t tightly around the hands. Rips and tears should be repaired immediately and stretched elastic replaced. It is a good idea to remove wristwatches and bracelets, because they tend to tear the bafe material.Dirty Rollers (Fig. 11.29). If the rollers are not cleaned periodically, radiolucent bands or white chalky debris will appear on the nished lm.Remedy. Rollers should be cleaned periodically by removing and soaking them in accordance with the manufacturer’s recommendations. A piece of extraoral or cleaning lm should be run through at the beginning of every work day to clean the rollers.Overlapped Films (Fig. 11.30). If the lms are fed into the processor too quickly, they overlap, and the processing solutions cannot reach the emulsion.Remedy. The operator should wait 10 seconds before putting the next lm into each processing track. If there are lms stuck together, it is recommended to wet those lms with water and gently separate them from each other. In this case, however, there still may be areas on the lms that were not processed properly, and gently separating the lms will just avoid tearing the emulsion.COMMON ERROR 11.1 THE DARKROOM (see also the Appendix)—cont’dBA• Figure 11.28 A, Artifact caused by a light leak in the daylight loader, resembling a large pathologic area in bone. B, Normal radio-graph of the same area. • Figure 11.30 Overlapped lms during automatic processing. • Figure 11.29 Bands of stain (arrows) from dirty rollers of an automatic processor. 138 CHAPTER 11 Film Processing TechniquesChapter Review QuestionsMultiple Choice1. If a safelight is adequate, the coin test will: a. Show an outline of the coin b. Be blurred c. Not show an outline of the coin d. Show a completely black lm e. None of the above2. e chemicals in the developing solution used to reduce the energized silver halide crystals to silver is: a. Hydroquinone and sodium carbonate b. Sodium thiosulfate and Metol c. Sodium carbonate and Elon d. Elon or Metol and hydroquinone e. Sodium sulte and sodium thiosulfate3. A clear radiograph can result from: a. Prolonged xing b. Prolonged time in the water bath c. No exposure d. Not turning on the radiographic unit e. All of the above4. In manual and automatic processing: a. Fixing follows developing b. Fixing comes before developing c. Developing follows xing d. Drying is never necessary e. Complete xing is never necessary5. If the temperature of the processing solutions is slightly above normal, radiographs of desired density may be best obtained by: a. Increasing the developing time b. Increasing the exposure time c. Increasing the xing time d. Decreasing the developing time e. Increasing the xing time2. e dark stain on the accompanying radiograph is as a result of: a. Developer contacting the lm before processing b. Air bubbles contacting the lm c. Contaminated xer solution d. Water splashing on the lm e. Fixer contacting the lm before processingCase-Based Critical Thinking ExerciseA patient presents to your dental facility for radiographs. e facility employs conventional lm-based radiography and the manual method of processing lms. ree of the radiographs taken reveal processing errors. Answer the fol-lowing questions accordingly:1. e processing error shown at the superior border on this radiograph can be remedied by: a. Not exposing the lm to cell phone light b. Making sure that the lms do not stick together c. Checking the safelight regularly d. Making sure that the whole lm is immersed in the developing solution e. Not exposing the lm to white light 139CHAPTER 11 Film Processing TechniquesNational Council on Radiation Protection and Measurements: NCRP Report No. 145, Radiation in Dentistry, 2004.Stabulas-Savage J, Kwan J, Phelan J: e eects of cell phone light on dental radiographic lm, Research 1:838, 2014.Suleiman OH, Spelic DC, Conway B, et al: Radiographic trends of dental oces and dental schools, J Am Dent Assoc 130:1104–1110, 1999.Swanson RL, Roethel FJ, Bauer H: Reuse of lead from dental X-rays, N Y State Dent J 65:34–36, 1999.ompson EM, Johnson ON: Essentials of dental radiography for dental assistants and hygienists, ed 9, Upper Saddle River, NJ, 2012, Pearson Education, Inc.White SC, Pharoah MJ: Oral radiology: Principles and interpretation, ed 7, St Louis, MO, 2013, Mosby.BibliographyAlcox RW, Jameson WR: Rapid dental x-ray lm processor for selected procedures, J Am Dent Assoc 8:517–519, 1969.Beideman RL, Johnson ON, Alcox RW: A study to develop a rating system and evaluate dental radiographs submitted to a third party carrier, J Am Dent Assoc 93:1010–1013, 1976.Eastman Kodak Co: Quality assurance in dental radiography, 1989. Rochester, NY: Health Science Division.Eastman Kodak Co: Waste management guidelines, 1994. Rochester, NY: Health Science Division.Langland OE, Langlais RP: Principles of dental imaging, Baltimore, MD, 1997, Williams & Wilkins.3. e operator did not pay attention to the dierent temperatures of the processing solutions while manually processing. e accompanying image resulted from this error and is best known as: a. Static electricity b. Overdeveloping c. Hot processing d. Reversed processing e. Reticulation

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