FILM Flashcards
Undesirable optical densities or blemishes on a radiograph or any other medical image.
ARTIFACTS
any irregularity on an image that is not caused by the proper shadowing of tissue by the primary x-ray beam.
ARTIFACTS
is something in the image that looks like it was created by the object but was in fact created by the process.
ARTIFACTS
radiographic artifacts occur in three areas:
exposure, processing, and handling.
are associated with the manner in which the radiographer conducts the examination.
Exposure artifacts
essential for producing artifact-free images.
Patient preparation
Unexpected foreign object such as jewelry
Improper patient preparation
Double exposure
Reuse of cassettes already exposed
Blur
Improper patient movement, including breathing
Grid cutoff artifacts
Improper patient positioning
Obscured detail
Poor screen-film contact
occur when the guide shoes in the turnaround assembly of the processor are sprung or improperly positioned.
Guide shoe marks
because of dirt or a chemical stain on a roller, which sensitizes the emulsion.
pi line
ause emulsion pick-off and gelatin buildup, which result in sludge deposits on the film.
Dirty Rollers
light or radiation fog and is usually a uniform dull gray.
Chemical Fog
Improper or inadequate processing chemistry can result in a special type of chemical fog
dichroic stain.
appears as a curtain effect on the radiograph.
Dichroic stain
Chemical stains on a radiograph can appear
yellow, green, blue, or purple.
Irregular or dirty rollers cause pressure during development and produce small circular patterns of increased OD.
Wet-Pressure Sensitization
Yellow-brown drops on film
Oxidized developer
Milky appearance
Underreplenished fixer
Greasy appearance
Inadequate washing
Brittle appearance
Improper dryer temperature or hardener in the fixer
can occur if the film is stacked too high
Pressure marks
can result if the temperature or the humidity is too high or if the film bin is not shielded adequately from radiation.
Image fog
White light leaks in the darkroom or within the cassette cause streak-like artifacts of increased OD.
Light or Radiation Fog
Rough handling before processing can cause
Pressure or Kink Marks
Three distinct patterns of static are
crown, tree, and smudge.
is caused by the buildup of electrons in the emulsion and is most noticeable during the winter and during periods of extremely low humidity.
Static
The yellow-brown stain that slowly appears on a radiograph after a long storage time indicates a problem with hypo retention from the fixer.
Hypo Retention
QA activities require attention from the imaging team, but they are principally the responsibility of the
radiologist and the imaging service management
is more tangible and obvious than QA.
qc
designed to ensure that the radiologist is provided with an optimal image produced through good equipment performance and resulting in minimal patient radiation dose.
qc
Quality control program consists of three steps:
Acceptance testing
2.Routine performance monitoring
3.Maintenance
QC is principally the responsibility of the
medical physicist.
The general purpose radiographic units have a minimum total filtration of
2.5 mm Al.
Filtration should be evaluated
annually or at any time after a change has occurred in the x-ray tube or tube housing.
these devices are automatic collimators that sense the size of the image receptor and adjust the collimating shutters to that size.
Positive beam-limiting collimators
Distance and centering indicators must be accurate to within
2% of SID
The spatial resolution of a radiographic imaging system is determined principally by the
focal-spot size of the x-ray tube.
Three tools used for focal-spot size measurement:
1.Pinhole camera
2.Star pattern
3.Slit camera
difficult to use and requires excessive exposure time.
pinhole camera
easy to use but has significant limitations for focal-spot sizes less than 0.3 mm.
star pattern
The standard for measurement of effective focal-spot size is the
slit camera.
Focal-spot size should be evaluated
annually or whenever an x-ray tube is replaced
annually or whenever an x-ray tube is replaced
annually
A variation in kVp of approximately
4%
