Embed Size (px)
Citation preview
IDEAL RADIOGRAPHY
DR. REVATH VYAS
PG II YEAR
CONTENTS
• DEFINITION
• IDEAL IMAGE CHARACTERISTICS
• FACTORS RELATED TO THE RADIATION BEAM
• FACTORS RELATED TO THE OBJECT
• FACTORS RELATED TO THE TECHNIQUE
• FACTORS RELATED TO RECORDING OF THE ROENTGEN IMAGE OF THE OBJECT
• DARK/ LIGHT IMAGE IDEAL IMAGE
• IDEAL QUALITY CRIETRIA
• CONCLUSION
• REFERENCES
DEFINITION
• An Ideal Radiograph is one that provides a great deal of information, the image exhibits proper density and contrast, have sharp outlines and are of the same shape and size as the object being radiographed.
• In HM Worth’s words; “An Ideal Radiograph is one which has desired density and overall blackness and which shows the part completely without distortion with maximum details and has the right amount of contrast to make the details fully apparent”.
IDEAL IMAGE CHARATERISTICS
IMAGE CHARACTERISTICS
Dental radiograph appears as a black-and-white imagepicture that includes varying shades of gray.
Radiolucent (Black or dark areas): A structure thatappears radiolucent on a radiograph lacks density andpermits the passage of the x-ray beam with little or noresistance. For example, air space appearsradiolucent.
Radiopaque (White or light areas): Radiopaquestructures are dense and absorb or resist the passage ofthe x-ray beam. For example, enamel, dentin, boneetc. appears radiopaque.
The characteristics of an Ideal Radiograph are:
A. Visual characteristic:
i. Density.
ii. Contrast.
B. Geometric characteristics:
iii. Sharpness or detail, resolution or definition.
iv. Magnification.
v. Distortion.
C. Anatomical accuracy of radiographic images.
D. Adequate coverage of the anatomic region of interest.
A diagnostic (ideal) radiograph provides a great dealof information:
• the images exhibit proper density and contrast
• have sharp outlines and
• of the same shape and size as the object.
The major imaging characteristics of x-ray film are
1. Radiographic density
2. Radiographic contrast
3. Radiographic speed
4. Film latitude
5. Radiographic Noise
6. Radiographic blurring
1) RADIOGRAPHIC DENSITY
The overall degree of darkening of anexposed film is referred to as radiographic density.
Measured as the optical density of an area of an x-ray film, where,
OPTICAL DENSITY = Log 10 Io
Io - intensity of incident light (from view box)
It - intensity of light transmitted through the film.
It
The measurement of film density is also a measure ofthe opacity of the film.
Optical density is 0 means 100% of the light is transmitted
Optical density is 1 means 10% of the light is transmitted
Optical density is 2 means 1% of the light is transmitted.
A film is of greatest diagnostic value when thestructures of interest are imaged on the relatively straightportion of the graph, between 0.6 to 3.0 optical densityunits.
Gross fog or base plus fog: an unexposed film,when processed, shows some density caused bythe inherent density of the base, added tint and thedevelopment of unexposed silver halide crystals.
The optical density of gross fog is 0.2 to 0.3
Radiographic density is influenced by
A.Exposure
B. Subject thickness and
C. Subject Density
A) Exposure:- The overall film density depends on thenumber of photons absorbed by the film emulsion
kVp the no. of photons reachingmA the film and thus
exposure time density of the radiographdistance b/w, the
focal spot & film
B) Subject Thickness: The thicker the subject, the morethe beam is attenuated and the lighter the resultantimage
The exposure (either kVp or time) should varyaccording to the patient’s size to produce radiographs ofoptimal density.
C) Subject Density: The greater the density ofa structure within the subject, the greater theattenuation of the x-ray beam.
Dense objects (which are strong absorbers)cause the radiographic image to be light andare radiopaque.
Less dense objects (which are weak absorbers) causethe radiographic image to be dark and are radiolucent.
Decreasing densities – enamel, dentin, cementum,bone, muscle, fat and air.
Metallic objects (eg. Restorations) are far denser thanenamel and hence better absorbers.
2. RADIOGRAPHIC CONTRAST
Defined as the difference in densities between lightand dark regions on a radiograph.
High contrast Shows both light areas
(short gray scale of contrast) and dark areas.
Low contrast Composed only of light gray
(long gray scale of contrast) and dark gray zones
H i g h L o w O p t i m u mC o n t r a s t C o n t r a s t C o nt ra st
A. Subject Contrast:
Influenced largely by the subject’s thickness, densityand atomic number.
Also is influenced by beam energy and intensity.
As the kVp of the x-ray beam increases, subjectcontrast decreases low kVp energies are used,subject contrast increases.
“KVP KILLS CONTRAST”
Changing the time or mA of the exposure (KVp constant) alsoinfluences subject contrast.
If the film is excessively light or dark, contrast ofanatomic structures is diminished.
B. Film Contrast:-
Describes the capacity of radiographicfilms to display differences in subject contrast,
A high-contrast film reveals areas ofsmall difference in subject contrast
Properly exposed films have morecontrast than underexposed (light films)
Film processing influences film contrast.Film contrast is maximized by optimal filmprocessing conditions.
Improper handling of the film, such as
a) Storage at too high a temperature,
b) Exposure to excessively bright safe, degrades filmlights contrast.
c) Light leaks in the darkroom
Fog on an x-ray film results in increase film density inturn reduces the film contrast. Common causes offilm fog are
a) Improper safelighting
b) Storage of film at too high a temperature, and
c) Development of film at an excessive temperature orfor a prolonged period.
Film fog can be minimized by proper filmprocessing and storage.
C) Scattered radiation:
Scattered radiation results from photons thathave interacted with the subject by compton orcoherent interactions.
Scattered radiation causes fogging of aradiograph.
Scattered radiation can be reduced by
a) Use a relatively low kVp
b) Collimate the beam to the size of the film, and
c) Use grids in extraoral radiography.
3) RADIOGRAPHIC SPEED:
Refers to the amount of radiation required to produce animage of a standard density.
A fast film requires a relatively low exposure to produce adensity of 1, whereas a slower film requires a longer exposure
Controlled largely by the size of the silver halide grains andtheir silver content.
The films most often used are kodak ultraspeed (group D) andkodak insight (group E or F).
Insight film is preferred because it requires only about halfthe exposure of ultra speed film and offers comparablecontrast and resolution.
F-speed film is faster than the D-speed filmbecause tabular crystal grains are used in theemulsion of F-speed film.
Film speed can be increased by processing the filmat a higher temperature
Processing in depleted solutions can lower theeffective speed.
It is always preferable to use fresh processingsolutions and follow the recommended processingtime and temperature.
4) FILM LATITUDE:
Measure of the range of exposure that can be recorded asdistinguishable densities on a film.
A film with a characteristic curve that has a longstraight-line position and a shallow slope has a widelatitude.
Wide latitude have lower contrast
Wide-latitude films are useful when both the osseousstructures of the skull and soft tissues of the facialregion must be recorded.
A high kVp produces images with a wide latitude andlow contrast. Recommended for imaging structureswith a wide range of subject densities.
5) RADIOGRAPHIC NOISE:
Is the appearance of uneven density of a uniformly exposedradiographic film.
Seen on a small area of film as localized variations in density.
Primary causes of radiographic noise are
A) Radiographic mottle
B) Radiographic artifact
A) Radiographic Mottle:-
1. On intraoral dental film, mottle may be seen as film graininess
2. Graininess is most evident when high temperature processingis used.
3. Mottle is also evident when the film is used with fastintensifying screens
Two important causes of radiographic mottle inintensifying screens are
1) Quantum mottle – caused by a fluctuation in the numberof photons per unit of the beam cross-sectional areaabsorbed by the intensifying screens.
2) Screen structure mottle is graininess caused by screenphosphors.
B) Radiographic Artifacts:
Radiographic artifacts are defects caused by
1. Errors in film handling, such as finger prints or bends inthe film, or
2. Errors in film processing, such as splashing developer orfixer on a film or marks or scratches from rough handling.
6. RADIOGRAPHIC BLURRING
Sharpness – ability of a radiograph to define an edge precisely(e.g., dentino enamel junction, a thin trabecular plate).
Resolution, or resolving power, is the ability of aradiograph to record separate structures that are close together.
Usually measured by radiographing an object made up of aseries of thin lead strips with alternating radiolucent spaces ofthe same thickness.
The resolving power is measured as the highest number of linepairs per millimeter.
Panoramic film-screen combinations can resolve about fiveline pairs per millimeter.
Periapical film has better resolving power, can delineate clearlymore than 20 line pairs per millimeter.
Radiograph of a resolving power
target consisting of groups of
radiopaque lines and radiolucent
spaces.
Numbers at each group indicate the
line pairs per millimeter
represented by the group.
Sharpness
A B
Distance (mm)
Den
sity
D1
D2
0 5 10 15 20
The boundary between two areas A & B appears very sharp
Unsharpness
A
Distance (mm)
Den
sity
D1
D2
0 .2 .4 .6 .8
The boundary between two areas A & B appears unsharp
B
The steeper the slope the more sharp the image appears. The shallower the slope the more blurred the image
Sharpness, unsharpness & lack of sharpness
•No image is perfectly sharp
•Every image has a certain lack of sharpness
•Unsharpness is an objective concept which can be measured
•Sharpness is our subjective perception of unsharpness, and depends on contrast and unsharpness
Contrast & perception of unsharpness
•We judge one image boundary to be sharperthan another, even though they are both equally unsharp, if the contrast of the first image is greater.
Image sharpness in extraoral radiographic projections is lostbecause.
a) Visible light and UV radiation emitted by the screen spreadabout beyond the point of origin and expose a film area largerthan the phosphor crystal
b) Intensifying screens with large crystals are relatively fast,
c) Fast intensifying screens have a relatively thick phosphorlayer,
image sharpness maximized by ensuring as close a contact aspossible between the intensifying screens and the film.
3) The presence of image on each side of a double-emulsion filmalso causes a loss of image sharpness through parallax.
In intraoral images, parallax is most apparent when wet filmsare viewed.
Radiographic blur is caused by
A) Image receptor (film and screen) blurring
B) Motion blurring, and
C) Geometric blurring
A. Image receptor blurring:
1. with intraoral dental x-ray film, the size andnumber of silver grains in the film emulsiondetermines image sharpness.
Finer the grain size finer the sharpness
slow-speed films have fine grains and fasterfilms have larger grains.
2. use of intensifying screens in extra-oralradiography has an adverse effect on imagesharpness.
In intensifying screens parallax distortion contributes to imageunsharpness because light from one screen may cross the film baseand reach the emulsion on the opposite side. Problem can besolved by incorporating dyes into the base
B) Motion Blurring:
Image sharpness also can be lost through movement of thefilm, subject or x-ray source during exposure.
C) Geometric Blurring:
Several geometric factors influence image sharpness
Image sharpness is improved by
a) Using as small focal spot area as possible
b) Increasing the distance between the focalspot ad the object (andfilm)
c) Reducing the distance between the object and the imagereceptor (film)
Parallax unsharpness results when double emulsion film is
used because of the slightly greater magnification on the side
of the film away from the X-ray source.
FACTORS RELATED TO RADIATION BEAM
IDEAL EQUIPMENT
•POINT SOURCE OF FOCAL SPOT
• IDEAL TARGET MATERIAL WITH high atomic number a high melting point, high thermal conductivity, and low vapor pressure
•Safe and accurate
•Capable of generating X-rays in the desired energy range and with adequate mechanisms for heat removal
IDEAL EQUIPMENT
•Small
•Easy to maneuver and position
•Stable, balanced and steady once the tubehead has been positioned
•Easily folded and stored
•Simple to operate and capable of both film and digital imaging
•Robust.
Ideal Distance from the focal spot on the target to the skin.
• The required focus to skin distances ( fsd) are:
• — 200 mm for sets operating above 60 kV
• — 100 mm for sets operating below 60 kV
Ideal X-ray beam characteristics
The ideal X-ray beam used for imaging should be:
• Sufficiently penetrating, to pass through the patientand react with the film emulsion or digital sensor andproduce good contrast between the different shadows
• Parallel, i.e. non-diverging, to prevent magnificationof the image
• Produced from a point source, to reduce blurring ofthe edges of the image, a phenomenon known as thepenumbra effect.
exposure
button
oil
filterfilament
X-ray Machine Components
• The smaller the focal spot (target), the sharper the image (teeth) will be.
• During x-ray production, a lot of heat is generated.• If the target is too small, it will overheat and burn up.
Line Focus Principle
Line Focus Principle
Apparent (effective) focal
spot size (looking at target
surface through PID)
Actual focal spot size
(looking perpendicular to
the target surface)
PID
Line Focus Principle
Apparent (effective)
focal spot size
Actual focal
spot size
Target
Cathode
(-)
Anode
(+)
PID
FACTORS CONTROLLING THE X-RA Y BEAM
1. Exposure time2. Tube current (mA)3. Tube Voltage (kVp)4. Filtration5. Collimation6. Inverse square law
1. Exposure time
X-ray Energy (keV)
Num
ber
of X
-rays
70
2 sec
1 sec
maximum energy
average energy
(no change)
(no change)
Exposure time is doubled, the number of photons generated is doubled, photon energies isunchanged.
• The quantity of radiation produced by an-x-ray tube is directlyproportional to the tube current and the time the tube is operated.
Quantity of radiation = Time x Tube current
2. Tube Current (mA):
mA (milliamperes)
X-ray Energy (keV)
Num
ber
of X
-rays
70
10 mA
5 mA
maximum energy
average energy
(no change)
(no change)
mAs or mAi
milliamperes (mA) x seconds (s)
milliamperes (mA) x impulses (i)
60 impulses = 1 second
10 mA x .5 seconds = 5 mAs
20 mA x .25 seconds = 5 mAs
mAi = 60 x mAs
• Increasing the KVp results in increase in1. The number of photons generated2. Their mean energy, and3. Their maximal energy.
• Higher the KVp greater the penetrability of the beam throughmatter.
3. Tube Voltage (KVp)
KVP (KILOVOLT PEAK)
X-ray Energy (keV)
Num
ber
of X
-rays
70 90
90 kVp
70 kVp
maximum energy
average energy
Half Value Layer (HVL):-
• The HVL is the thickness of an absorber, required to reduce byone half the number of x-ray photons passing through it.
• As the average energy of an X-ray beam increases, so does itsHVL.
• Only photons with sufficient energy to penetrate through anatomicstructures and reach the image receptor are useful for diagnosticradiology.
Filtering an x-ray beam with aluminum preferentially removes low-energy photons,
thereby reducing the beam intensity while increasing the mean energy of the residual
beam.
4. Filtration:
Inherent filtration :• a. Glass wall of the x-ray tube• b. Insulating oil and• c. Barrier Material0.5 to 2mm of aluminum
External filtration:• Aluminium Disks.
Total filtration = Inherent filtration + External filtration.
• Total Filtration 1.5mm of aluminum to 70KVp• 2.5mm for all higher voltages.
Inherent
Glass window
of x-ray tube
Added
Aluminum filter (s)
Total 70 kVp
1.5 mm
2.5 mm
Total Filtration
Oil/Metal barrier
filter
PID
• To reduce the size of the x-ray beam therefore the volume ofirradiated tissue.
• Round and rectangular collimators most frequently used indentistry.
• Scattered radiation minimized by collimating the beam.
5. Collimation
collimated
beamcollimator
target
(x-ray source)
front views side view
Collimation
2.75 inches (7 cm) = maximum diameter of circular beam or maximum length
of long side of rectangular beam at end of PID.
Collimator
Al Filter
• Collimators - may either have a round or rectangular opening.
Circular collimator : a) cone shaped beam - 2.75 inches in diameterb) considerably larger than the size of two intraoral periapical
filmsc) increased skin dose to the patient.Rectangular collimator : a) restricts the size of the X-ray beam to an area slightly larger than a size of 2 intraoral b) significantly reduces the patient exposure
Collimation: • Reduces the exposure area • Number of scattered photons reaching the film-improves
image quality
Quality
Quantity
average energy
number of x-rays
(10) (20)
Quality vs. Quantity
kVp
mA
Time
Filtration
No change
No change
• The intensity is inversely proportional to the square of the distancefrom the source.
I1/I2 =(D2)2/(D1)2
• If a dose of 1 gray (GY) is measured at a distance of 2m a dose of 4GYwill be found at 1m and 0.25 GY at 4m.
6. Inverse Square Law
kVp the no. of photons reachingmA the film and thus
exposure time density of the radiographdistance b/w, the
focal spot & film
“KVP KILLS CONTRAST”
FACTORS RELATED TO OBJECT
Subject Thickness: The thicker the subject, the
more the beam is attenuated and the lighter the
resultant image
Subject Density: The greater the density of astructure within the subject, the greater theattenuation of the x-ray beam.
Dense objects (which are strong absorbers)cause the radiographic image to be light andare radiopaque.
Subject Contrast:
Influenced largely by the subject’s thickness,density and atomic number.
FACTORS RELATED TO TECHNIQUE
IDEAL PROJECTION GEOMETRY
The basic principles of projection geometry
(shadow casting)
• The focal spot should be as small as possible
• Focal spot to object distance should be as long as possible.
• Object to film distance should be as small as possible.
• Long axis of object and film planes should be parallel.
• X-ray beam should strike the object and film planes at right angles.
• There should be no movement of the tube, film or patient during exposure
( given by Manson and Lincoln)
•The anatomy of the oral cavity doesnot always allow all these idealpositioning requirements to besatisfied.
• In an attempt to overcome theproblems, two techniques forperiapical radiography have beendeveloped:•The paralleling technique
•The bisected angle technique.
• Paralleling cone technique has the potential to satisfy four of the five ideal requirements mentioned earlier.
• However, the anatomy of the palate and the shape of the arches mean that the tooth and the image receptor cannot be both parallel and in contact.
• So, the image receptor has to be positioned some distance from the tooth.
IDEAL PATIENT POSITIONING
•For intraoral radiography the patientshould be positioned comfortably in thedental chair, ideally with the occlusalplane horizontal and parallel to the floor.
•For most projections the head should besupported against the chair to minimizeunwanted movement.
FOR IOPA
FOR OCCLUSAL
For BITE-WING
• The tab or bite-platform should be positioned on the middle of the film packet and parallel to the upper and lower edges of the film packet.
• The film packet should be positioned with its long axis horizontally for a horizontal bitewing or vertically for a vertical bitewing.
• The posterior teeth and the film packet should be in contact or as close together as possible.
• The posterior teeth and the film packet should be parallel — the shape of the dental arch may necessitate two separate film positions to achieve this requirement for the premolars and the molars.
• In the horizontal plane, the X-ray tube head should be aimed so that the beam meets the teeth and the film packet at right angles, and passes directly through all the contact areas.
• In the vertical plane, the X-ray tubeheadshould be aimed downwards (approximately 5°-8° to the horizontal) to compensate for the upwardly rising curve of Monson.
• The positioning should be reproducible.
• Assessment of caries and restorations — films should be well exposed and show good contrast to allow differentiation between enamel and dentine and to allow the enamel — dentine junction (EDJ) to be seen.
• Assessment of periodontal status — films should be under-exposed to avoid burn-out of the thin alveolar crestalbone.
For OPG
IDEAL RECEPTOR POSITIONING
•The ideal requirements for the position of the image receptor and the X-ray beam, relative to a tooth include:
•The tooth under investigation and the image receptor should be in contact or, if not feasible, as close together as possible
•The tooth and the image receptor should be parallel to one another
•The image receptor should be positioned with its long axis vertically for incisors and canines, and horizontally for premolars and molars with sufficient receptor beyond the apices to record the apical tissues
•The X-ray tubehead should be positioned so that the beam meets the tooth and the image receptor at right angles in both the vertical and the horizontal planes
•The positioning should be reproducible.
Factors related to recording of the roentgen image of the object.
IDEAL FILM STORAGE
Ideally films should be stored:
• In a refrigerator in cool, dry conditions
• Away from all sources of ionizing radiation
• Away from chemical fumes including mercury and mercury-containing compounds
• With boxes placed on their edges, to prevent
pressure artefacts.
IDEAL DARK ROOM CONDITIONS
• General cleanliness (daily), but particularly of work surfaces and film hangers (if used).
• Light-tightness (yearly), by standing in the darkroom in total darkness with the door closed and safelights switched off and visually inspecting for light leakage
1. Darkroom lamp
2. Electric fan,
3. Rack for drying films,
4. Storage rack for intraoral
hangers,
5. Bulletin board,
6. Exposure and processing
chart for dental X-ray films,
7. Drip pan,
8. Shelf,
9. Timer,
10. Utility safe lamp,
11. Goose neck faucet,
12. Loading area,
13. Processing area,
14. Splash board,
15. Hot and cold water
valves,
16. 8 × 10 dental
processing tank,
17. Utility sink,
18. Supply cabinet for
chemicals, cassettes and
other accessoriesSchematic Darkroom Layout
• Safelights (yearly), to ensure that these do not cause fogging of films.
• Checks are required on:
Type of filter — this should be compatible with the coloursensitivity of film used, i.e. blue, green or ultraviolet
Condition of filters — scratched filters should be replaced
Wattage of the bulb — ideally it should be no more than 25 W
Their distance from the work surface — ideally they should be at least 1.2 m (4 ft) away
Overall safety (i.e. their fogging effect on film)
The simple quality control measure for doing this is known as
the coin test.
COIN TEST
Chemical solutions
These should be:• Always made up to the manufacturers‘ instructions
taking special precautions to avoid even trace amounts of contamination of the developer by the fixer, e.g. always fill the fixer tank first so that any splashes into the developer tank can be washed away before pouring in the developer
• Always at the correct temperature• Changed or replenished regularly — ideally every 2
weeks — and records should be kept to control and validate these changes
• Monitored for deterioration. This can be done easily using radiographs of a step-wedge phantom:
Cassettes
• Regular cleaning of intensifying screens with a proprietary cleaner
• Regular checks for light-tightness, as follows: • 1. Load a cassette with an unexposed film and place the
cassette on a window sill in the daylight for a few minutes
• 2. Process the film — any ingress of light will have fogged (darkened) the film
Cassettes
• Regular checks for film/screen contact, as follows:• 1. Load a cassette with an unexposed film and a similar
sized piece of graph paper
• 2. Expose the cassette to X-rays using a very short exposure time
• 3. Process the film — any areas of poor film/screen contact will be demonstrated by loss of definition of the image of the graph paper.
• A simple method of identification of films taken in similar looking cassettes, e.g. a Letraset letter on one screen.
Digital phosphor storage plates
• Regular cleaning
• Regular visual checks for scratches or other defects
IDEAL VIEWING CONDITIONS
• Human visual system is capable of distinguishing only about 60 gray levels at any time under ideal viewing conditions.
• Considering the typical viewing environment in the dental operatory, the actual number of gray levels that can be distinguished falls to less than 30.
• So, ideal viewing conditions are required for better diagnosis
• An even, uniform, bright light viewing screen (preferably of variable intensity to allow viewing of films of different densities) (see Fig. 18.1)
• A quiet, darkened viewing room
• The area around the radiograph should be masked by a dark surround so that light passes only through the film
• Use of a magnifying glass to allow fine detail to be seen more clearly on intraoral films
• The radiographs should be dry.
DARK/ LIGHT RADIOGRAPH IDEAL RADIOGRAPH
REDUCTION
•An overexposed or grossly overdeveloped film will be too dark for convenient viewing, owing to the excessive deposit of silver which obscures the image detail.
•A photographic reducer contains an oxidizing agent, potassium ferricyanide which oxidizes the silver to silver ferrocyanide, which in turn is dissolved by the solution of sodium thiosulphate.
•This is known as the Farmer’s Reducer and consists of two solutions:•Solution A : Potassium ferricyanide 75 grams + Water to make 1000 ml.
•Solution B : Sodium thiosulphate crystals 240 grams. + Water to make 1000 ml.
•Method: Take one part of Solution A and four parts of Solution B, and add twenty seven parts of water.
• Immerse the radiograph in the mixed solution and watch carefully. When the film has been sufficiently reduced, it should be washed in running water for 30 minutes.
•The process of reduction should be carried out in a weak artificial light, as bright light causes rapid deterioration of the solution.
•The Solution A and Solution B should be mixed just prior to their use.
Chemical intensification of radiographs
•A radiograph may be too light because of, underexposure, under development or both.
• Instead of repeating the radiograph, chemical intensification may be done.
•Most of the intensification methods act by converting the silver which forms the image into a compound which is more opaque, more colored or of a different physical form.
• A number of commercially available intensifying solutions are present:
• In-4 Chromium intensifier.
• In-5 Silver intensifier
• Copper iodide intensifying solution.
• XR-10 intensifying solution.
• Line Toner solution— this is made of three solutions:
• Solution A : Diglycolic acid 60 grams
• Sodium Hydroxide 36 grams
• Water 750 ml
• Solution B: Boric nitrate 14 grams
• Potassium fluoride 1 gram
• Water 100 ml
• Solution C: Potassium ferricyanide 5 grams
• Sodium nitrite 1 grams
• Water 100 ml
• The processed radiograph which is of low density is immersed in the intensifying solution for a period of three to eight minutes depending upon the density increase required.
IDEAL QUALITY CRIETERIA
For IOPA
•The image should have acceptable definition with no distortion or blurring.
•The image should include the correct anatomical area together with the apices of the tooth/teeth under investigation with at least 3–4 mm of surrounding bone.
•There should be no overlap of the approximal surfaces of the teeth.
•The desired density and contrast for film captured images will depend on the clinical reasons for taking the radiograph, e.g.• to assess caries, restorations and the periapical
tissues films should be well exposed and show good contrast to allow differentiation between enamel and dentine and between the periodontal ligament space, the lamina dura and trabecullarbone.
• to assess the periodontal status films should be underexposed to avoid burnout of the thin alveolar crestal bone
•The images should be free of coning off or cone cutting and other film handling errors.
•The images should be comparable with previous periapical images both geometrically and in density and contrast.
For OPG
•All the upper and lower teeth and their supporting alveolar bone should be clearly demonstrated
•The whole of the mandible should be included
•Magnification in the vertical and horizontal planes should be equal
•The right and left molar teeth should be equal in their mesiodistal dimension
•The density across the image should be uniform with no air shadow above the tongue creating a radiolucent (black) band over the roots of the upper teeth
•The image of the hard palate should appear above the apices of the upper teeth
•Only the slightest ghost shadows of the contralateral angle of the mandible and the cervical spine should be evident
•There should be no evidence of artefactual shadows due to dentures, earrings and other jewellery
•The patient identification label should not obscure any of the above features
•The image should be clearly labelled with the patient’s name and date of the examination
•The image should be clearly marked with a Right and/or Left letter.
For Bite-wing
• The image should have acceptable definition with no distortion or blurring.
• The image should include from the mesial surface of the first premolar to the distal surface of the second molar — if the third molars are erupted then the 7/8 contact should be included.
• The occlusal plane/bite platform should be in the middle of the image so that the crowns and coronal parts of the roots of the maxillary teeth are shown in the upper half of the image and the crowns and coronal parts of the roots of the mandibular teeth are shown in the lower half of the image, and the buccal and lingual cusps should be superimposed.
•The maxillary and mandibular alveolar crests should be shown.
•There should be no overlap of the approximal surfaces of the teeth.
•The desired density and contrast for film captured images will depend on the clinical reasons for taking the radiograph, e.g.• to assess caries and restorations films
should be well exposed and show good contrast to allow differentiation between enamel and dentine and to allow the enamel–dentine junction (EDJ) to be seen.
• to assess the periodontal status films should be underexposed to avoid burn-out of the thin alveolar crestal bone
•The image should be free of coning off or cone cutting and other film handling errors.
•The image should be comparable with previous bitewing images both geometrically and in density and contrast.
CONCLUSION
• AN IDEAL RADIOGRAPH IS AN END PRODUCT OF SEVERAL FACTORS WHICH NEEDS TO BE FOLLOWED IN DAY TO DAY RADIOGRAPHY.
• IDEAL RADIOGRAPH HELPS NOT ONLY IN PROPER DIAGNOSIS BUT ALSO IN PROPER TREATMENT PLANNING AND ALSO TO SEE THE TREATMENT OUTCOME.
REFERENCES
• WHITE AND PHAROAH - 6TH EDITION
• ERIC WHAITES – 3RD EDITION
• HERRING AND HOWERTON – 3RD EDITION
• WEUHRMANN – 5TH EDITION
• KHARJODKHER – 2ND EDITION
THANK YOU
