CR Flashcards
What approach is necessary to understand how a CR system functions?
It is necessary to isolate the different parts of the CR imaging system.
and study each part as independent.
What are the four key components of a Computed Radiography system?
The x-ray machine,
CR-imaging plane,
CR-Processor,
Image display workstation.
How is the latent image made visible in CR?
When the detector is scanned by a laser beam to produce light (photostimulable luminescence) that is subsequently converted into electrical signals.
What does the pattern of the electrical signals in CR represent?
The pattern of the remnant radiation which forms the latent image.
When does the conversion of the latent image into electrical signals occur?
When the imaging plate is inserted into the CR image processor to process the image.
What are some terms that are synonymous with Computed Radiography?
Photostimulable luminescence (PSL),
Storage phosphor radiography (SPR),
Digital luminescence radiography (DLR),
Photostimulable phosphor radiography (PSP), and
Digital storage phosphor (DSP).
What is luminescence in the context of phosphor materials?
Any emission of light from a phosphor material.
Define fluorescence in relation to phosphor materials.
The immediate emission of light from a phosphor material under stimulation.
What is phosphorescence?
: The emission of light sometime after the original stimulus (exposure has occurred).
What type of phosphorescence do CR systems utilize? What does it require?
Stimulated phosphorescence, which requires a laser beam to restimulate the phosphor.
How is the photostimulable phosphor housed? What does it resemble?
In a rugged cassette, and it appears similar to a film-screen cassette.
List the seven layers of a CR imaging plate.
- Protective layer
- Phosphor layer
- Reflective layer
- Conductive layer
- Anti-halo/Color layer
- Support layer
- Backing layer.
Describe the protective layer of the imaging plate.
A very thin, tough, clear plastic that protects the phosphor layer.
What is the function of the phosphor layer (active layer)?
It “traps” electrons during x-ray exposure.
What materials are the phosphors in the active layer typically made of? Provide examples.
Phosphors from the barium fluorohalide family (i.e., fluorohalide, chlorohalide, or bromohalide crystals).
What is added to the phosphor layer as a “doping agent” or impurity? What does it help create?
Europium, which helps create “F centers” or “electron traps” or “meta-stable sites”.
What do “F centers” act like in the phosphor crystal lattice? What do they do?
They act like “electron holes” that capture or trap electrons released from phosphor atoms when exit radiation strikes the phosphor layer.
