59 terms

Ch 8 - Screen/Film IR Systems

STUDY
PLAY

Terms in this set (...)

Radiolucent
A substance that is easily penetrated by the x-ray beam is termed:
Backscatter
Radiation coming from the cassette back and the cassette tray that is scattered back toward the film.
Phospors
Fluorescent crystals which coat an intensifying screen.
Fluorescence
The ability of phospors to give off light.
99%
What percentage of the x-ray image is formed by the screen light?
Screen Speed
The efficiency of a screen in converting x-rays to light.
300-400 RS
What is the typical screen speeds used for general purpose x-ray?
Slower
Would you use faster or slower screen speed for extremeties?
50-100
What range of speed would you use for extremities?
Quantum Mottle.
As the screen speed increases, the detail decreases due to:
Protect film from light and bending or scratching
The function of a cassette is to:
Reduce the amount of exposure required to produce an image.
The purpose of intensifying screens is to:
Produce an image with more recorded detail
An intensifying screen with smallest crystals will:
Require more mAs to maintain density.
An intensifying screen with smallest crystals will:
Rare Earth Elements
Which type of phosphors are used today for general purpose screens?
F
(T/F) When cleaning intensifying screens, you should pour the liquid cleaner on to the screen.
Image Blur
Poor contact between the film and screen causes:
Silver Halide Crystals
Film emulsion consists of a mixture of gelatin and:
Film/Screen Contact
A wire mesh took is used to test:
The color of light emitted by the screen.
The spectral sensitivity of the film must be matched to:
The maximum radiographic density produced by a film.
The horizontal upper portion, or shoulder, of a sensitometric curve indicates:
Exposure time; Patient dose; mAs
The use of intensifying screens reduces:
50-70 degrees; Protection from radiation exposure; 30-50% humidity.
Optimal film storage conditions include:
RS 300-400
For general purpose radiography, a relative screen speed (RS) of __________ is typically used.
Increases
As the screen speed increases, quantum mottle ______________:
9 feet
A screen contact image should be viewed at a distance of at least:
The color of light emitted by a phosphor
What does Spectral Emission refer to?
F
(T/F) A radiopaque material is easily penetrated by the x-ray beam.
F
(T/F) The front of the cassette has a layer of lead foil that prevents backscatter.
T
(T/F) The ID blocker is for patient identification
T
(T/F) A screen with greater efficiency requires less exposure and is said to be faster.
T
(T/F) Damaged hinges on a cassette can cause poor film/screen contact.
T
(T/F) Inherent film characteristics may include sensitivity (Speed), contrast, and spectral sensitivity.
F
(T/F) Films with larger crystals and thicker crystal layers produce a slower speed and greater detail.
F
(T/F) On the Hunter and Driffield curve (H&D) a steep, vertical curve indicates a long scale of contrast.
F
(T/F) A film with a wide latitude will show more detail than a film with narrow latitude.
Quarterly
How often should screen contact test be performed?
Absorbs backscatter, preventing fogging the film.
What is the purpose of the lead foil layer in the cassette?
Between the back of the cassette and the back intensifying screen.
Where is the lead foil layer located in the cassette?
Blue and Green
What colors are typical of the spectral emission of rare earth intensifying screens?
Locate the cassette that was used and remove the hair, clean with compressed air.
If you see a white image in the shape of a hair on a radiograph, what should you do?
Can of compressed air; Camel hair or sable hair brush; Commercial screen cleaner; Soft lint-free disposable applicators
What screen cleaning supplies should be on hand in the radiology department?
The pressure will cause fog.
Why is it a poor practice to stack x-ray film boxes flat on top of each other?
50-70 degrees
What is the optimum temperature for long-term film storage?
Base & Fog level
What film characteristic is represented by the toe of the sensitometric curve?
Film Speed
What film characteristic is represented by the straight line portion of the sensitometric curve?
Contrast, latitude
What film characteristic is represented by the straight-line slope of the sensitometric curve?
Maximum density (D-max)
What film characteristic is represented by the shoulder of the sensitometric curve?
Incorrect matching of film & screens increases patient dose.
Why is it important to match the spectral sensitivity of the film to the spectral emission of the screen?
RS 50-100
What is the relative screen speed used for limbs?
A wide range of densities can be recorded on the film.
Define the term latitude.
T
(T/F) As the contrast of the film decreases, latitude increases.
Artifacts
Unwanted marks or images that appear on the film
Spectral Emission
The color of light emitted by a phosphor refers to:
Specral Sensitivity
The portion of the electromagnetic spectrum to which the film is most sensitive.
T
(T/F) Latitude and contrast are inversely related.
H&D Curve (Hirter & Driffield)
Another name for the sensitometric curve?
The films ability to transmit light.
What is the optical density (OD) of the film?
When film is unexposed, the film has an OD of 0.15-0.20.
What is base+fog density?