Radiographic Artifacts

Dr.AmandeepL2013V40M

Department Of Veterianry MedicineGADVASU

Introduction

Structure or appearance that is not normally present

on the radiograph and is produced by artificial means

Detrimental to interpretation by decreasing

visualization or altering the appearance of area of

interest

Classification

• Processing

• Exposure

• Handling & Storage

Classification

Simplify by dividing them into two broad categories:

◦ those that involve the entire film

◦ those that are localized to one or more areas on the

film

Various Artifacts

Improper Exposure

a. White radiograph

Too low mAs or kvp

Under estimated body part measurement

Inc FFD

b. Dark radiograph

Too high mAs or kVp

Over estimated body part measurementde

Dec FFD

Prevention

• Check settings

• Tube to film distance

• Body part measurement

• Avoid use of exhausted developer

Improper developing

a. Too dark b. Too light

– Film may have been in

the developer too long

– Developer temperature

may be too high

– Check the temperature of

the developer and adjust

time accordingly if hand

processing is done.

– Film may not have been

in the developer long

enough

– Developer temperature

may be too low & time

was not adjusted

accordingly

– Exhausted developer-

chemicals

c. Unevenly developed

– Chemical levels are uneven resulting in uneven

levels of developing and fixing

– Generally seen at top of the film when using hand

processing

– May also see uneven developing if the chemicals

are not stirred prior to use (hand processing)

Chemicals not Stirred

white

streaky

appearance

over the entire

film

Uneven Chemical Levels

not exposed, is developed,

and not fixed

not exposed, developed,

and partially fixed

exposed, developed, and

fixed

not exposed, but is

developed and fixed

d. Brown stains

Fog

• Any additional

unwanted density that

results in a gray film

• Loss of contrast which in

turn affects the image detail

Causes

• Excessive pressure

• Heat- film should be stored at <68 F

• Light- from outside source or safelight

• Humidity- should be 30-50%

• Chemical- over developing

• Old film

• Certain gases

• Scatter radiation

Prevention

• Store film in cool place with moderate humidity

• Store vertically & not stack.

• Check for any light leaks

• Safelight must be at proper spectrum & proper

distance from counter

• Use a grid when necessary

Improper Screen-Film Combination

• Results in poor quality images

• Given screen will emit a certain light spectrum

• Chosen film must be sensitive to that spectrum

• Films and screens are often classified as “blue” or

“green” & they must match

Grids

• If body part is greater than 10cm thick

• Grid must be leveled, within its focal zone & aligned

with beam

• Grids may be portable, or mounted permanently

beneath the table

Grid alignment

Grid alignment

Upside down grid

This results in extreme loss of

primary radiation at the

periphery, with near normal

transmission at the center.

Grid cut off

• Grid is not aligned with beam

• Results in absorption of primary radiation

• Image is too light and there is poor contrast

• Grid lines are visible as numerous very narrow

parallel lines

Too light and grid lines seen

Motion

• Image is blurred

• Resolution is poor

• May be motion of patient, tube, or cassette

• Problem especially with non-sedated animals

• Panting causes patient motion

Motion blurrness

blurry appearance edges are

unsharp

Prevention

• Sedate the animal

• Proper restraint

• Avoid hand holding cassettes

• NEVER hand hold x-ray unit

Screen/Cassette Abnormalities

• Old cassettes

– decreased

film-screen contact

=decreased detail

• Screen craze

– small cracks

throughout the screen-

these areas are underexposed

Double Exposures

• Film is darker than a single exposure

• May be the same image

– inadvertent double click.

– animal has not moved.

• May be two separate images

– generally a film is exposed, forgotten & not

developed, then exposed again

Double exposure

IMAGE OFF CENTRE

• using the bucky

– not pushed in all the way

– concurrent grid cutoff

• table top

– image not centered on the film

– will cause no problem with the image

TABLE TOP AND BUCKY NOT PUSHED IN

Localized Artifacts

Static Electricity

• two patterns-smudge and tree

• black marks on the film

• electrons are passed to the film during handling therefore exposing the film

• common problem especially in cold dry climates

STATIC ELECTRICITY

Avoiding Static Electricity

• maintain moderate humidity in the area

• do not slide the film across surfaces-this excites electrons

• clean screens with a cleaner containing an anti-static agent

Debris

• May be associated with the screen, on the cassette

or grid, or on the table or collimator window

• These are white artifacts

• Closer the debris is to the film, the sharper its

margins will appear

• Common debris includes hair, and dust particles

• Sometimes air is trapped on film

Rough Handling

• Black “crescent” marks

– film has been creased prior to processing

– very common problem

• White “crescent” marks

– similar cause to black marks but more severe

– termed “SOLARISATION”

Chemical Spills

• Streaks, spills or fingerprints

• Color will depend on specific chemical(s)

involved

• Developer causes black stains

• Fixer causes white stains

• Improper rinsing causes brown stains

Localized Fog-Light Leaks

• Common problem causing black areas (exposed)

• Multiple potential sources

– storage bin light leak

– cassette light leak

– light turned on during the time the film is being fed

into the processor

Localized Fog-Pressure

• Dark gray or black artifact

• Localized pressure applied to the film

• May be a result of rough handling

• Margins are often irregular and fuzzy

PRESSURE FOG AND EMULSION SCRATCHES

Objects Within the Beam

• Not related to the primary image

• Decreased the quality of the image

• Common sources include the whip on portable

machines, restraining devices, iv lines, ECG leads,

ET tubes, etc

Kissing Defect

• Can occur with

automatic or manual developing

• 2 films completely or

partially stick together

• Films are not properly processed

• Can see the outline of one

film on the other

Manual Restraint Artifacts

• Hands in the primary beam

• Gloved hands in the primary beam

• Remember that lead gloves do not protect your hands within the primary beam-they only protect from scatter

Improper Positioning

• Animal not properly positioned

• Body parts such as front or hind legs

superimposed over thorax or abdomen

• Compromises radiographic evaluation

• Positioning is generally more difficult without

sedation

Thanks