Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
64 Cards in this Set
- Front
- Back
|
What is a cassette |
A light proof encasement that is designed to hold x-ray film and intensifying screens in close contact |
|
|
What are intensifying screens |
Fluorescent sheets of plastic |
|
|
What is the general-use of a cassette |
To hold x-ray film sandwiched between 2 intensifying screens |
|
|
What part of the image receptor is responsible for converting the x-ray radiation into visible light |
Intensifying screens |
|
|
The front of the cassette must be _________ to light yet __________ to x-rays
|
Opaque; radiolucent |
|
|
Why is the back of the cassette lined with lead |
To absorb back scatter |
|
|
If the cassette did not absorb back scatter how would this effect the film |
The film would be foggy |
|
|
How is close contact of the film and the intensifying screens created |
The cassette is lined with felt or foam pressure pads on both sides |
|
|
How are cassettes cleaned |
With mild soap and water |
|
|
Why should all cassettes be numbered |
Noticeable defects on a radiograph can be traced to the "problem cassette" |
|
|
What are intensifying screens |
Sheets of luminescent phosphor crystals bound together and mounted on a cardboard or plastic base |
|
|
What happens when the intensifying screens are struck by x-radiation |
The crystals fluoresce, and the x-rays are converted into visible light |
|
|
What is the primary purpose of an intensifying screen |
To reduce the amount of radiation exposure required to produce a diagnostic radiograph |
|
|
What are the three properties that determine the efficiency of an intensifying screen |
Must have a high level of x-radiation absorption Must have a high x-radiation-to-light conversion with suitable energy and color There must be little or no "afterglow" once radiation has ceased |
|
|
What is afterglow |
The tendency of a phosphor to still give off light after the x-radiation has stopped |
|
|
What are the advantages of having large crystals in intensifying screens |
Faster Less radiation is necessary to expose x-ray film |
|
|
What are the disadvantages of having large crystals in intensifying screens |
Less detail Grainy image |
|
|
What are the advantages of having small crystals in intensifying screens |
More detail Less grainy image |
|
|
What are the disadvantages of having small crystals in intensifying screens |
Larger amounts of radiation are required to exposed an x-ray Slower |
|
|
Thickness of the phosphor layer on intensifying screens will have what effects on the film |
Increased x-ray absorption Increased light emissions Decreased detail |
|
|
What are the 3 basic screen speed categories |
Slow Medium Fast |
|
|
Slow screen speed have a ____ definition, but require _________ exposure time |
High; longer |
|
|
Fast screen speed reduce ____ time/patient |
exposure |
|
|
How are the screens cleaned |
With distilled water Use gauze Stand upright and open to dry |
|
|
Using excessive screen cleaners leaves ______ |
Artifacts |
|
|
How should the screens be stored |
In low humidity Stored upright Prevent pressure artifacts |
|
|
What is the purpose of x-ray film |
To provide a permanent record containing essential diagnostic information |
|
|
What is an x-ray film composed of |
Polyester base coated on both sides Light=sensitive emulsion |
|
|
What does the emulsion on x-ray films contain |
Silver halide crystals |
|
|
When visible light or x-rays interact with silver halide crystals, an ________ _______ is formed |
Invisible image |
|
|
What is a latent image |
An invisible image on the x-ray film after it is exposed to ionizing radiation or visible light before processing |
|
|
The greater the number of silver halide crystals exposed the _______ the film once developed |
Blacker |
|
|
What are the two types of film |
Screen Nonscreen |
|
|
Screen films are sensitive to _________ ____and less sensitive to _________ __________ |
Fluorescent light; ionizing radiation |
|
|
What is an advantage of screen films |
They require less exposure to x-rays to produce a quality image |
|
|
Nonscreen Film is more sensitive to _____ ______ than ________ _________ |
Ionizing radiation; fluorescent light |
|
|
What is an advantage of nonscreen film |
Higher detail |
|
|
What is a disadvantage of nonscreen film |
Requires greater exposure to x-rays |
|
|
What affects the film's speed |
The different-sized silver halide crystals |
|
|
How is a film's speed determined |
The amount of exposure required to produce an image with adequate density |
|
|
What is film latitude |
The exposure range over which acceptable densities are produced |
|
|
What are the different types of film latitiude |
Wide-latitude Narrow-latitude |
|
|
What is wide-latitude |
Film will accept a significant variation in exposure factors or processing without exhibiting a great change in density |
|
|
Wide-latitude film is also known as |
Forgiving film |
|
|
What is narrow-latitude film |
Requires considerably less changes in exposure factors or processing to alter the density |
|
|
Narrow-latitude film is also known as |
High-contrast film |
|
|
What are the three different film speeds |
Fast Medium Slow |
|
|
What is an advantage of fast film |
Requires less exposure by x-rays or fluorescent light |
|
|
What are the disadvantages of fast film |
Produces a grainier image Lacks definition Has a narrow-latitude |
|
|
What is a disadvantage of slow film |
Requires greater exposure by x-rays or fluorescent light |
|
|
what are the advantages of slow film |
Produces an image that is less grainy Has greater definition Has a wide-latitude |
|
|
How should film be stored |
On end (vertical) 10-15C 40-60% humidity Not near any ionizing radiation, or vapors from formalin, hydrogen peroxide, or ammonia can reach it |
|
|
If film is stored near ionizing radiation or damaging vapors what can happen |
The film will fog |
|
|
What are common artifacts on film |
Too dark Too light Film gray/lack of contrast Lack of detail Heavy lines (generalized) Inconsistent film density Black marks (not generalized) Clear areas on film Yellow radiograph |
|
|
What can cause film to be too dark |
Over exposure to kVP or mAs Overdevelopment Over measurement of the part under examination Machine out of calibration Source image distance is off for grid use |
|
|
What does SID mean |
Source Image Distance |
|
|
What causes film to be too light |
Underexposure to kVp or mAs Underdevelopment S-ray tube failure Incorrect film-screen combination Machine timer out of calibration Drop in incoming line voltage |
|
|
What causes a lack of contrast on film |
Too much kVp Radiation fog Light leak in darkroom Storage fog due to its too hot or humid Chemical fog Film out of date Lack of a grid w use of high kVp Double exposure Incorrect bulb wattage or filters for safelight in darkroom |
|
|
What causes a lack of detail in film |
Increased object-film distance Blurring due to poor screen-film contact Blurring due to pt motion Blurring due to x-ray tube motion Distorted image due to central x-ray not directed at center of film Double exposure |
|
|
What causes heavy lines on film |
Grid is out of focal range Grid is out of alignment to x-ray central beam Grid is upside down Gird is damaged Roller marks for automatic processor |
|
|
What causes inconsistent film density |
Collimation of primary beam Bucky tray not positioned directly under primary x-ray beam Cassette not locked into Bucky tray correctly Light leak into cassette Quantum mottle Target damage Variable screen-film contact |
|
|
What can cause black marks on film |
Crimping or folding of film tow films sticking together during development Static electricity Developer on film before processing Fingerprints as a result of developer on hands while loading or unloading cassette |
|
|
What can cause Clear areas on film |
Hair in cassette Scratch in film emulsion Line due to scratch on screen surface Contrast medium on cassette or table Air bubbles on film during manual processing Fingerprints due to film handling with contaminated hands |
|
|
What can cause yellowing of film |
Fixer splashes on film before developing Premature age due to improper fixation Film sticking together during fixing process Incomplete washing |
