Bushong Chapter 19: Screen-film Radiographic Artifacts

Artifact

1) Are undesirable optical densities or blemishes on a

radiograph or any other medical image

2) Any irregularity on an image that is not caused by the

proper shadowing of tissue by the primary x-ray beam

Screen-film radiographic artifacts can....

`interfere with the visualization of anatomical structures and can lead to misdiagnosis

Radiographic artifacts occur in three areas:

1) Exposure

2) Processing

3) Handling

Exposure Artifacts

1) Incorrect screen-film match, poor screen-film contact,

warped cassettes, and improper positioning of the grid

all can lead to such artifacts

2) Improper patient position, patient motion, double

exposure, and incorrect screen-film radiographic

technique can result in very poor images that some

call artifacts.

*Poor technique is leading cause of repeats

Artifacts worn by the patient:

1) Necklaces 6) Zippers & Catches

2) Pendants 7) Variety of jewelry

3) Hearing Aids *contrast staining can cause

4) Chains artifacts on gowns

5) Body & Facial piercings

In cases of trauma ______, _______, _______, and ______ should remain in place

1) Pins * Internal artifacts cannot be removed and

2) Fasteners and should be noted, just as in trauma

3) Dressings cases

4) Splints

Clear instructions

__________ are required to encourage understanding and cooperation in patients

When radiographers mix up cassettes, ________________________

double exposures can occur; repeat examination is required

Penguin

Exposure artifacts are usually easy to detect and correct

If the patient is positioned for examination when he x-ray tube is not centered to the table or Bucky tray, __________

grid cutoff artifacts may occur

When one is trying to locate an object that has been swallowed,__________________.

this is not an artifact

Processing Artifacts

1) Most are pressure-type artifacts caused by the transport

system of the processor

2) Pressure-type artifacts usually sensitize the emulsion

and appear as higher optical density (OD).

3) Those that scrape or remove emulsion appear as lower

OD

Penguin

Processing artifacts are eliminated with a proper processor QC program and frequent cleaning

Roller Marks:

1) Guide shoe marks

2) Pi lines

Guide Shoe Marks

1) Guide shoe marks occur when the guide shoes in the

turnaround assembly of the processor are sprung or

improper positioned

2) If the guide shoe is used before the developer, the

ridges in the guide shoes press against the film,

sensitize it, and leave a characteristic mark

3) Guide shoe marks can be found on the leading edge of

or the trailing edge of the film parallel to the direction

of film travel through the processor

Pi Lines

1) Occur at 3.1416 inch intervals because of dirt or a

chemical stain on a roller, which sensitizes the

emulsion

2) Because the rollers are 1" in diameter, 3.1416"

represents one revolution of a roller, and the artifact

appears perpendicular to the film's direction of travel

through the processor

Dirty Rollers

1) Dirty or warped rollers can cause emulsion pick-off and

gelatin buildup, which result in sludge deposits on the

film

2) These artifacts usually appear as sharp areas of

increased or reduced OD

Chemical Fog

1) Looks like light or radiation fog and is usually a

uniform dull gray

2) Improper or inadequate processing chemistry can

result in a special type of chemical fog called a

dichroic stain

Dichroic

means two colors

Dichroic Stain

1) Improper or inadequate processing chemistry can result

in a special type of chemical fog

2) Term generally applied to all chemical stains

Chemical Stains

on a radiograph can appear yellow, green, blue, or purple

Curtain Effect

In slow processors, the chemistry may not be squeezed

properly from the film, and it either runs down the

leading edge of the film or runs up the trailing edge

Wet-Pressure Sensitization

1) A common artifact that is produced in the developer

tank

2) Irregular or dirty rollers cause pressure during

development and produce small circular patterns of

increased OD

3) Processing artifacts in digital radiography(DR) are

different from those with screen-film because the

method of producing the visible image is electronic

rather than chemical

Handling and Storage Artifacts

1) Image fog can result if the temperature or the

humidity is too high or if the film bin is not shielded

adequately from radiation.

2) Pressure marks can occur if film is stacked too high

Penguin

Proper facility design helps reduce handling and storage artifacts

Light or Radiation Fog

1) White-light leaks in the darkroom or within the cassette

cause streak-like artifacts of increased OD

2) If the safe light has an improper filter, the safe light is

too bright, or the safe light is too close to the film

processing tray, the image may be fogged

3) Films left in the x-ray examination room during an

exposure can become fogged by radiation

4) Radiation fog and safe light fog look alike

Pressure or Kink Marks

1) Characteristics artifacts can be caused by improper

handling or storage either before or after processing

2) Rough handling before processing can cause scratches

and kink marks

3) Although the kink mark may appear as a fingernail

mark, it is not, it is caused by the kinking or abrupt

bending of film

4) Both events usually appear as increased OD

Static

1) The most obvious artifact

2) Caused by the buildup of electrons in the emulsion and

is most noticeable during the winter and during periods

of extremely low humidity

Three distinct patterns of static:

1) Crown

2) Tree

3) Smudge

Hypo Rentention

1) The yellow-brown stain that slowly appears on a

radiograph after a long storage time indicates a problem

with hypo retention from the fixer

2) With this event, not all of the residual thiosulfate from

fixing was removed during washing, and silver sulfide

slowly builds up and appears yellow in the stored

radiograph