Image Receptors Flashcards
(103 cards)
The item the x-ray image is formed on
Image receptor
Give three examples of image receptors
Film, plate or digital sensor
What is meant by ‘ fogging of the film’?
When some photons do not have enough energy to make a useful interaction with the receptor, therefore resultant scatter of photons can degrade the image.
What are the two ways to capture an x-ray image?
Film or digital
What are the two types of film image receptors that can be used?
direct action film
indirect action film
What are the two types of digital image receptors?
-solid state sensor
- photo-stimulate phosphor (PSP)
What image receptor is described:
An actual piece of film which is sensitive to x-rays that is wrapped in a packet.
used intra-orally, x-ray directly acts on silver halide crystals in film emulsion
Direct film
What image receptor is described:
a film inside a cassette which contains intensifying screens, that x-ray photons interact with to produce light photons, exposing the film to produce the image.
used extra-orally, light from intensifying screens act on silver halide crystals in film emulsion
Indirect film
What image receptor is described:
Two types of sensors:
- CCD and CMOS
These work by converting light into electrons
Solid state sensor
What does CCD stand for?
Charge-coupled device
What does CMOS stand for?
Complimentary metal-oxide semiconductor
What image receptor is described:
Latent image produced by the interaction of x-rays with the phosphor layer on the plate, which is then scanned by a laser to produce an image.
Phosphor- stimulable phosphor (PSP)
which digital sensor can sometimes not be tolerated well by patients, due to it’s large and bulky nature?
Solid state sensors
Which digital sensor has better image resolution?
Solid state sensors
What are the two sides of a phosphor plate?
Phosphor coating side ( white)
Black side with orientation dot
which side of a phosphor plate is the image formed on?
Phosphor coating side ( white)
what side of the phosphor plate should be visible through the window of a protective bag?
The black side
Describe the stable excited state
Image plate placed in patients mouth and phosphor coating is exposed to x-rays which causes a reaction within the phosphor.
Describe the unstable excited state
The plate is dropped into the vista scan unit where it is scanned by a red laser
What type of light is emitted to be differed into an image once the phosphor plate is scanned by red laser?
Blue light
What are the 4 layers that make up a charge couple device? And what is their function?
front cover
scintillator layer (converts x-ray energy to light)
silicon layer ( converts light into electrical signal)
back cover ( incorporates a cable to carry signal to pc)
What is a ‘pixel’?
Electrons within each cell
What is the difference between CCD and CMOS?
CMOS - signals sent from each individual cell (pixel)
CDD- signals sent from lines of cells (pixels)
What is the issue with digital images?
There is no orientation dot visible on the image. This means you may have images that could be very east to turn the wrong way and get muddled up.