Radiographic image quality /prosthodontic courses

RADIOGRAPHIC IMAGE
INDIAN DENTAL
ACADEMY
Leader in continuing
Dental Educationwww.indiandentalacademy.com

INTRODUCTION
Image quality of a radiographic image is described as
“The subjective judgment by clinician of the
overall appearance of a radiograph”
 The ability of a film to record each point in object as
point on film
 But in radiology this point to point reproduction is
never perfect
www.indiandentalacademy.com

5 IMPORTANT COMPONENTS IN IMAGING SYSTEM
Imaging is the Process of Converting Tissue Characteristics into a Visual Imagewww.indiandentalacademy.com

RADIATION CHARACTERISTICS WHICH
INFLUENCE THE QUALITY OF IMAGE
QUALITY
• VOLTAGE
• kVp
• EXPOSURE TIME
QUANTITY
• AMPERAGE
MILLIAMPERAGE
• MILLIAMPERE -
SECONDS
INTENSITY
• QUALITY
• QUANTITY
• DISTANCE
• INVERSE SQUARE
LAW
• HALF VALUE LAYER
X-RAY BEAM

X-RAY BEAM QUALITY
• Mean Energy & Penetration Ability of X ray beam
• Wave length determines its energy & penetrating power
• Quality, wavelength, energy are controlled by
TUBE VOLTAGE

Inside the dental x ray tubehead
• TUBE VOLTAGE :Potential difference between
Cathode & Anode that gives K.E. to electrons &
makes electrons move from cathode to anode

KILOVOLTAGE PEAK kVp
• Maximum or peak voltage of alternating current
• In an AC polarity of line current alternate so
polarity of x ray tube alternates at
same frequency
Filament -ve
Target +ve
Flow of electrons
Filament +ve
Target -ve
No electron flow
Inverse voltage
reverse biaswww.indiandentalacademy.com

INCREASE IN
VOLTAGE
INCREASES
SPEED OF
ELECTRONS
ELECTRONS
STRIKE TARGET
WITH GREATER
FORCE AND
ENERGY
PENETRATING
BEAM WITH A
SHORTER
WAVELENGTH
Voltage determines speed of electrons

1kV=1000V
DENTAL RADIOGRAPHY
65 TO 100kV
85 TO 100 kV SHORTER
WAVELENGTH MORE ENERGY
OVER PENETRATION
65 TO 75kV LONGER
WAVELENGTH LESS ENERGY
DONOT ALLOW AEQUATE
PENETRATION

EXPOSURE TIME
• Time during which x rays are produced
• It is measured in impulses as x rays are created in a
series of bursts or pulses rather than in a continuous
stream
• 1 impulse occurs in 1/60 of second ( 60impulses in 1s)

X-RAY BEAM QUANTITY
 It is the number of x rays produced in
dental x ray unit
 AMPERAGE determines amount of electrons passing
through the cathode filament
 AMPERE - unit used to measure no of electrons or
current flowing through the cathode filament

 1milli ampere = 1/1000 of ampere
 A change in mA does not change K.E of electrons
 So only quantity is changed
 In dental radiography use of 7 to 15mA is required

MILLIAMPERE- SECONDS
• Both mA and s have a direct influence on no of
electrons produced by cathode filament
• 1 mAs = 6.25 x 1015 electrons per second
• When milliamperage is increased the exposure time
must be decreased and vice versa, if the density of
exposed radiograph is to remain same
Milliamperes X Exposure Time = mAs

X RAY BEAM INTENSITY
• INTENSITY is defined as product of quality (energy
of each photon) quantity (no of x ray photons) per
unit area per unit time of exposure
• Higher kvp , mA, exposure time,
Intensity of x ray beam
INTENSITY = NO OF PHOTONS X ENERGY OF EACH PHOTON
AREA X EXPOSURE RATE

DISTANCE
• The distance between
source of radiation and film
has marked effect on intensity
• The distances to be considered are
SOD , OID, SID
• As x rays travel from source their
intensity decreases
• The relation between distance and intensity
is explained by inverse square law.
s
I
o

INVERSE SQUARE LAW
• The intensity of radiation is inversely proportional to
square of distance from source of radiation
x
xD = 1 ft
Area = x2
Intensity = 144
units/sq.inch
D = 2 ft
Area = 4x2
Intensity = 36
units/sq.inch
D = 3 ft
Area = 3x2
Intensity = 16
units/sq.inch
2x
2x
I1/I 2= D2
2 / D 1
2

HALF VALUE LAYER
• To reduce intensity of x ray beam , aluminum filters are
placed in path of beam
• These are used to remove low energy, less penetrating,
long wavelength x rays
• Al filters increase mean penetrating
capacity of x rays while reducing
their intensity
• The thickness of material which
reduce intensity by half is
called half value layer.

Ag HALIDE
CRYSTALS
X-rays LIGHT
Grains of
metallic
silver
This gives film its
dark appearance
The Overall degree of darkening of an exposed
film is called its RADIOGRAPHIC DENSITY

X-ray tube
Object
Plot of incident x-ray
beam intensity
Plot of transmitted x-ray
beam intensity

Consider the light transmitted through an area of a
film
Incident light
intensity (Ii )
Transmitted light
intensity (It)
Transmittance (Transmission ratio)= It / Ii
Opacity = 1 / Transmittance = Ii / It
Density = Log10 Opacity = Log10 Ii / It

Range of densities on a film
Ii It Transmit
tance
Opacity Density
100
0.01
0.1
1.0
10.0
100
0.0001
0.001
0.01
0.1
1
10000
1000
100
10
1
4
3
2
1
0
4 3 2 1 0

1
2
3
4
1 2 3 4
Log relative exposure
Density
Shoulder
Toe
CHARACTERISTIC CURVE /HURTER AND DRIFFIELD CURVE
GF
DMax
Straight line
portion
SHOULDER AND TOE
VERY HIGH AND VERY LOW VARIATION
IN EXPOSURE MAKE VERY SMALL
CHANGES IN DENSITY
GREATEST DIAGNOSTIC
VALUE WHEN STRUCTURES
OF INTEREST ARE IMAGED
ON RELATIVELY STRAIGHT
PORTION OF GRAPH
BETWEEN 0.6 AND 3.0
GROSS FOG OR BASE PLUS FOG MINIMAL DENSITY SHOWN WHEN
AN UNEXPOSED FILM IS PROCESSED {0.07+0.05= 0.12(0.2to 0.3)}www.indiandentalacademy.com

when other exposure factors
remain constant
EFFECT ON DENSITY
INCREASED KVp INCREASED DENSITY
DECREASED KVp DECREASED DENSITY
INCREASED mA INCREASED DENSITY
DECREASED mA DECREASED DENSITY
INCREASED TIME INCREASED DENSITY
DECREASED TIME DECREASED DENSITY
EXPOSURE FACTORS

SUBJECT THICKNESS
THICKER
SUBJECT
MORE BEAM IS
ATTENUATED
LIGHTER
RESULTING
IMAGE
The dentist should vary exposure factors
( either kVp or time) according to patient’s
size to produce radiograph of optimal
density

SUBJECT DENSITY
 Greater the density of a structure in subject, greater
is attenuation of beam
 Dense objects ( which are strong absorbers) cause the
image to be light ( radiopaque)
 Low density objects are weak absorbers, allow most
photons to pass through and cast a dark area on film
( radiolucent)
Order Of Decreasing Density
Enamel >Dentin > Cementum>bone>muscle>fat>airwww.indiandentalacademy.com

INCREASED DENSITY
If developer solution is too hot
Prolonged developing
DECREASED DENSITY
If developer solution is cold
Developing time is too short
Underactive/exhausted
solutions

CONTRAST
• It is defined as difference in densities between light
and dark regions on a radiograph
AN IMAGE WHICH
SHOWS BOTH DARK
AND LIGHT AREAS
HAS
HIGH CONTRAST/
SHORT GRAY SCALE
AN IMAGE WHICH
SHOWS ONLY LIGHT
GRAY AND DARK
GRAY ZONES HAS
LOW CONTRAST/
LONG GRAY SCALE

A.SUBJECT CONTRAST
 Range of characteristics of subject that influences
radiographic contrast
 It is the difference in x ray intensity transmitted
through one part of subject as compared to other
 This difference in intensity of beam caused by object
is subject contrast
MUSCLE BONE

1.THICKNESS DIFFERENCE I
 No .of x rays through thin part
are greater than thick part IS
IS - Intensity of x ray beam IL
transmitted through thin part
IL - Intensity of x ray beam through
thick part
SUBJECT CONTRAST = IS/IL
IS > IL

2. DENSITY DIFFERENCE
 The difference in density between body tissues is
one of the most important factor causing subject
contrast
 The greater density of tissue (mass/ volume)
greater is the ability to attenuation
 For e.g: consider same thickness of ice floating in
water
 Water attenuates more of beam than ice

3. ATOMIC NUMBER
 Attenuation of x ray beam by photoelectric effect
makes most important contribution to subject contrast
 Photoelectric effect is increased in substances with high
atomic number
 Bone (ca # 20, P # 15) attenuates more x rays than
muscle(H #1, N#7)
 Muscle and fat due to their little difference in atomic
number show little difference in attenuation

Contrast media:
 The use of contrast materials with high atomic
number( 53 # I , 56 # Ba) gives high subject contrast
 Photoelectric absorptions of x rays in barium and
iodine are proportionally much greater than in bone
and tissue

 Low kVp produce high subject contrast, provided
the kVp is high enough to penetrate part being
examined adequately
 If the kVp is too low almost all xrays are attenuated
in pt and never reach film
Increased
kVp
More
penetration
in to tissues
Interact
by
compton
effect
Increased
scattered
radiation
Image
noise and
decreased
contrast
4.RADIATION QUALITY

 In general , low kVp gives high subject contrast (short scale
contrast)
 High kVp gives low subject contrast(long scale contrast)
SHORT
SCALE
EVERY THING
IS BLACK/
WHITE
ON FILM
WITH FEWER
SHADES OF
GRAY IN
BETWEEN
LONG
SCALE
LONG SCALE
OF SHADES OF
GRAY IN
BETWEEN
LIGHTEST AND
DARKEST
PORTIONS OF
IMAGE

GRIDS
• The grid which is placed between subject and film ,
preferentially removes the scattered radiation and
spares primary photons
• This reduces nonimaging
exposures
• Increase subject contrast

B. FILM CONTRAST
• It describes capacity of radiographic film to display
differences in subject contast
• A high contrast film reveals areas of small
difference in subject contrast more clearly than
does a low contrast film
Greater the slope
of curve greater
is the contrast
So film A Shows
greater change in
optical density
than B
Film B with
shallow slope
has wide
latitude
So B records
greater range of
exposures
within useful
density rangewww.indiandentalacademy.com

SOLUTION TO
THIS PROBLEM
• DECREASE
SUBJECT
CONTRAST BY
INREASING kVp
•USE FILM
WITH LONG
LATITUDE
LOSS OF CONTRAST IN THICK AND THIN BODY
SECTIONS WHEN USING HIGH CONTRAST FILMwww.indiandentalacademy.com

C. SCATTER AND FOG
• Reduces contrast
• Scattered radiation that reaches film/ film-screen
combination produces unwanted density
SCATTERED RADIATION OCCURS DUE TO SO TO MINIMISE
INCREASED THICKNESS OF PART
INCREASED FIELD SIZE COLLIMATE BEAM TO SIZE OF FILM
USE GRIDS IN EXTRAORAL
RADIOGRAPHY
INCREASED ENERGY OF BEAM USE LOW KVPwww.indiandentalacademy.com

FOG
 Defined as those silver halide crystals that are
developed even though they are not exposed by light/
x rays
 If accidental exposure occurs – exposure fog
Although origin of both is different , both cause
unwanted film density which lowers contrast
Fog is increased by
 High speed film, improper film storage
 Excessive time/temp of developer
 Contaminated/exhausted developerwww.indiandentalacademy.com

FILM
CHARACTERISTICS
RADIOGRAPHIC
SPEED
RADIOGRAPHIC
NOISE
RADIOGRAPHIC
MOTTLE
ARTIFACT
LATITUDE

SPEED
• refers to “amount of radiation required to produce
an image of standard density”
• how efficiently the light-sensitive agents in a film
emulsion react to energy (e.g., x-rays or light)
• Expressed as reciprocal of exposure ((in roentgens)
required to produce an optical density of 1 above
gross fog
• Controlled largely by size of silver halide grains and
their silver contentwww.indiandentalacademy.com

• Fast film requires relatively less amount of radiation
than a slow film
• The film speeds most commonly used in dental
imaging are D(ultra speed),E(Ekta speed,F(insight )
• D-speed is the slowest film of the three, and F-
speed is the fastest.
• Insight film is preferred as it requires only half of
exposure ultraspeed and offers comparable contrast
and resolution

FLAT CRYSTALS INTERCEPT MORE LIGHT BUT THE TOTAL AMOUNT OF
SILVER DOES NOT INCREASE.
INCREASE IN SPEED WITH LESS NOTICEABLE GRAIN.
AS A RESULT, EKTASPEED PLUS FILM DELIVERS EXCELLENT IMAGE
QUALITY WHILE AT THE SAME TIME REDUCED RADIATION
Conventional
silver-halide
crystals are
pebble shaped
KODAK
T-GRAIN
Emulsion
crystals
Are flat
INSIGHT
ULTRA
SPEED

• Film speed can be increased slightly by processing
at high temp, this is achieved at expense of
increased film fog and graininess
• Adding radiosensitive dyes to film emulsion
• Processing in depleted solutions lowers speed

LATITUDE
• Film latitude is a measure of range of exposures
that can be recorded as distinguishable densities on
a film
• A film optimized to record wide latitude can record
a subject with a wide range of subject contrast
Curve with Long straight
line portion and shallow
slope has wide latitude .
wide variations in amount
of radiation exiting the
subject can be recorded

• Wide latitude films are used when both osseous
structures of skull and soft tissues of facial region must
be recorded
• Wide latitude films have lower contrast
• To some extent operator can modify latitude of an
image
• High kVp produce image with wide latitude and low
contrast
• Wide latitude film is recommended for imaging
structures with a wide range of subject densities

RADIOGRAPHIC NOISE
• It is the appearance of uneven density of a
uniformly exposed radiographic film
• Seen on small areas of film as localised variations in
density
• Primarily due to Radiographic Mottle And Artifacts
• Artifacts are defects caused by errors in film
handling, such as fingerprints, bends, errors in film
processing such as splashing of developer or fixer
on a film or marks or scratches from wrong handlingwww.indiandentalacademy.com

• Mottle may be seen as film graininess which is
caused by visibility of silver grains in film emulsion
especially when magnification is used to examine
an image
• Two important causes are screen structure mottle,
quantum mottle
• Screen structure mottle is graininess caused by
screen phosphors
• Most evident when fast screens with large crystals
are used

• X-ray interactions are random events.
• Therefore, “uniform” x-ray exposure does not produce
uniform film darkening.
• Regional variability in the film darkening is called
“QUANTUM MOTTLE.”
• Caused by fluctuation in number of photons per unit of
beam cross-sectional area absorbed by intensifying
screen
• Quantum mottle decreases as x-ray exposure is
increased.

• Consequently, “fast” screen-film systems will have
more quantum mottle than “slower” systems
• Longer exposure required by slower systems tend to
average out beam pattern and there by reduce
quantum mottle
Quantum mottle
masks low contrast
objects
Quantum mottle is
worse for small
objects

MAGNIFICATION
• When an object is placed in path of
beam it will cast a shadow on film that
will show some degree of
enlargement.
• If the object is round and flat like a coin, its
magnified image will be round but larger than coin
• amount of magnification (M)
SIZE OF IMAGE
SIZE OF OBJECT
M =

To achieve minimal
magnification
1.Keep focus film
distance as large as
possible(SID)
2.Keep film as close to
object as possible(OID)

INCREASING SOURCE OBJECT DISTANCE
RESULTS IN IMAGE WITH INCREASED
SHARPNESS AND LESS MAGNIFICATION
THIS IS DUE TO DECREASED
DIVERGENCE

Target
16” Target
8”
Target
16”
INCREASE SOURCE-OBJECT DISTANCE, DECREASE
MAGNIFICATION
DECREASE OBJECT-FILM DISTANCE, DECREASE MAGNIFICATION

DECREASING OBJECT AND IMAGE RECEPTOR
DISTANCE INCREASES SHARPNESS AND LESS
MAGNIFICATION

DISTORTION
• It is misrepresentation of true size and shape of object being
radiographed
• Distortion results from unequal
magnification of different parts
of same object
Amount of distortion depends on
• Thickness
• Position
• shape

THICKNESS
• Thick objects are more distorted as different parts
are at different distances from x ray film,
each part will be magnified by
different amount
• This will cause Shape of the
image of most thick objects
to be distorted
• Only The part of the thick object
that is parallel to the film will be
undistorted

POSITION
Distortion of position of objects
may occur if they are at different
distances from the film
• Two opaque objects A &B are
present inside a circle
• Object A is more medial than B
but A is farther from film
• The film image of object A will be lateral to image of object of B
• This is because distance between A and midline has been
magnified much more than distance between B and central
beam
• Distortion of position is minimal when the object is near the
central part of x ray beam and the object is placed as close to
the film as possible

• Size distortion
• Occurs due to improper orientation of film and
object. To minimize
1. Position the film parallel to long axis of object
2. Orient central ray perpendicular to object and film
BUT AS OID
INCREASES THERE IS
SOME AMOUNT OF
MAGNIFICATION ,
LOSS OF DEFINITION
BY INCREASING
UNSHARPNESS
PARALLELING
TECHNIQUE BEST
INCORPORATES
IMAGING
PRINCIPLES

Central ray should be perpendicular to long
axes of tooth and film .if it is not, then
distortion occurs

Central ray is
perpendicular to film
But object is not parallel
with film
Foreshortening occurs
Central ray is
perpendicular to object
Not to film
Elongation occurs

• SHAPE DISTORTION
• The sphere that lies in center of beam
will exhibit round (undistorted)
magnified image
• The image of laterally placed sphere
will be an ellipse because x ray beam
sees diameter of sphere that is
not parallel to film

SHARPNESS
• SHARPNESS is a ability of x ray film or
film screen system to define an edge precisely
• E.g DEJ, a thin trabecular pattern
• An unsharp edge can be easily seen if contrast is
high but a sharp edge may be poorly visible if
contrast low.

SHARPNESS
A B
Distance (mm)
Density
D1
D2
0 5 10 15 20
The boundary between two areas A & B appears very sharp

Unsharpness
A
Distance (mm)
Density
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

MOTION UNSHARPNESS
• Caused by motion of examined
object/film during exposure
• Depends only on velocity(v) of motion(mm/sec)and
exposure time(t) (seconds)
• Restricting movement of pt and
• reducing exposure time helps to
resolve problem

ABSORPTION UNSHARPNESS
• Due to gradual change in x-ray absorption across an
object’s edge or boundary
• Thickness of absorber presented to beam changes
• Effect is poorly defined margin of solid objects
X-Ray
Tube
X-Ray
Tube
X-Ray
Tube

PENUMBRA
Pene = almost ; umbra = shadow
• It is the region of partial illumination
that surrounds umbra / complete image
• UMBRA is the region of complete image

• Focal spot is not a point. it has finite dimensions ,
usually ranging from 0.3 -2mmsquare
• The focal spot acts as if it were composed of many
point sources of x rays with each point source
forming its own image of an object
• The edges of each of these images will not be in
exactly the same spot on film

• Fig . Shows edge of an object formed by
two x ray sources A &B which
represents opposite ends of
focal spot
• If A & B are only sources of x-rays
there would be two
overlapping images recorded
on the film
• But A and B are only opposite
ends of focal spot, a continuous line
of x ray sources
• Object edge is imaged many times
between edge B and edge A

• The image formed by line(focal spot)
of x rays is not sharp at the edge and
varies in density
• This zone of unsharpness is called
GEOMETRIC UNSHARPNESS,
PENUMBRA, EDGE GRADIENT
• Which represent area at which margins caused by
many point sources of x rays in the focal spot overlap

• The resulting zone of unsharpness cause loss of image
clarity by reducing sharpness and resolution
• 3 methods to minimize loss of clarity and improve
quality are
1.use as small as an effective focal spot
2.increase the distance between focal spot and object by
using long open ended cylinder(increase SID)
3.minimize the distance between object and film
( decreasedOID)

Larger the focal spot greater the loss
of image sharpness

SMALL ANGLE has
greater wearing
effect on target
INCREASED
IMAGE
SHARPNESS AND
RESOLUTION
but small
effective focal
spot
LOSS OF IMAGE
CLARITY
Decreased heat
generation,
prolonged tube
life
LARGE ANGLE
distributes electron
beam over large
surface

RESOLUTION
• The resolution of a system is its ability to
demonstrate closely spaced structures in the
subject as separate entities in the image
E.g. The trabeculae pattern of bone
• The resolution of an image refers to its ability
to show small structures separately
• The smaller the structures visible the higher
the resolution of the image/system

MEASUREMENT OF RESOLUTION
• The resolution is expressed in terms of the smallest
spacing /highest spatial frequency of high and low
dense structures visible in the image
• This is done subjectively by radiographing a test
object consist of a grid of closely spaced lines,
alternately radiopaque and radiolucent.

• RESOLUTION TEST OBJECT
Each radiopaque line and corresponding space is
known as a line pair
The spacing of line pairs is expressed as line pairs
per millimetre (lp/mm)
LINE PAIRS/ MM
Depicts how well you
can see the
differences in
structures
More lines=more
detailwww.indiandentalacademy.com

COMPARISON OF RESOLUTION
• The resolution of different imaging systems may be
compared by reference to the Modulation Transfer
Function (MTF) of each system
Modulation = frequency of change (of structure ,
etc.)
• MTF is a method of assessing the success with which
modulations of structure (detail) in an object are
transferred into modulations of density or luminance
in the image

Modulation in the image
• MTF = ------------------------------------
Modulation in the object
–MTF = 1 means that image reproduces
exactly the variations in the object.
–It is a characteristic of imaging systems
that, as the detail in the object becomes
finer, the ability of the system to record
that detail becomes progressively reduced.

TO PRODUCE RADIOGRAPHS OF OPTIMAL
DIAGNOSTIC QUALITY
• Radiographs should record complete areas of
interest on the image
• In case of IOPA, full length of roots and 2mm of
periapical bone must be visible
• If evidence of pathology is present area of entire
lesion plus some surrounding normal bone should
show on one radiograph

• Radiographs should have least possible amount of
distortion
• Most distortion is caused by improper angulation of
x ray beam rather than by curvature of structures
being examined or inappropriate positioning of
receptor
• Close attention to proper positioning of receptor
and x ray tube results in diagnostically useful
images

Simple quality control procedures assure that
high-quality patient radiograph
PATIENT POSITIONING
• Film should be close to object to reduce OID
• Center the beam to area of interest
• Get area of interest parallel to beam /film
• Restrain motion of patient and communicate
with patient
• Use short exposure times

IMAGE RECEPTOR
• Use correct screen-film
combination
• Low contrast films have wider latitude and
large margin of error in producing acceptable
radiograph
• Use highest speed system that will provide
adequate contrast and density

PROCESSING
• Although exposure factors are crucial in
influencing density, contrast faulty processing
can adversely affect diagnostic quality of
properly exposed radiographs
• Even the best exposure conditions can be
compromised with poor processing technique

Method 1: Sensitometry and Densitometry
• A sensitometer is used to expose a film, followed by
standard processing of the film
• processed film will have a defined pattern of optical
densities that are measured with a densitometer
• The densitometer measurements are compared to the
densities of films exposed in ideal conditions
• A change in densitometer values indicates a problem with
either the development time, temp or the developer
solutions
• Advantages
• Accuracy and Speed
• Disadvantage
• Expense of additional equipment

Method 2: Stepwedge
• An aluminum stepwedge , with each step of the aluminum at
1 millimeter thick and 3 to 4 mm wide, with at least six steps
• A film is exposed through the stepwedge ,with the same
machine settings, film placement and stepwedge placement
used for each daily exposure
• The processed film is compared visually with a reference film
• A change in density of one or more steps indicates a problem
with either the development time, temperature or the
developer solutions
Advantage
• Cost effectiveness
Disadvantage
• Less precision

• Method 3: Reference Film
• A film exposed and processed under ideal conditions is
attached to the corner of a view box as a reference film
• Subsequent films are compared with the reference film
• Advantage
• Cost effectiveness
• Disadvantage
• Least sensitivity

INTENSIFYING SCREENS AND EXTRAORAL
CASETTES
• Visual inspection of cassette integrity
• Examination of intensifying screen for scratches
• Development of an unexposed film that has been in
the cassette exposed to normal lighting for one
hour or more

DARK ROOM INTEGRITY
• While in a darkroom with the safelight on, place a
metal object (such as a coin) on unwrapped film for
a period that is equivalent to the time required for
a typical darkroom procedure
• Develop the film
• Detection of the object indicates a problem with
the safelight or light leaks in the darkroom

X RAY MACHINE
• Should be inspected by qualified expert
• The following parameters should be checked
• X ray out put
• Collimation
• Beam energy, timer, mA
• Tube head stability
• Focal spot size

CONCLUSION
• Quality of image is influenced at every stage
• We must identify the mistakes and try to improve them.
• But we must realize that in improving one aspect we may
weaken another.
• There is a complex interrelationship between many of the
factors concerned, including all of the image characteristics
discussed .
• Only when we have studied all the ramifications of image
production we will be able to understand fully how quality
may be optimized.

REFERENCES
1. Stuart C White , Michael J Pharoah ,
Textbook Of Oral Radiology Principles And
Interpretation
2. Christensens Physics Of Diagnostic Radiology

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Radiographic image quality /prosthodontic courses

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