Image receptors 1 Flashcards
what are the two ways to capture an x-ray image?
film and digital
remember digital has no orientation dot so can get muddled up
name 2 types of film
direct action film
indirect action film
what do the x-rays act on in direct action film?
directly on silver halide crystals in film emulsion
what do the x-rays act on in indirect action film?
on intensifying screens to produce light that acts on silver halide crystals in film emulsion
what is indirect action film used for?
extra-oral radiographs
what are the 2 types of digital x-ray imaging?
solid state sensors
photostimulable phosphor psp
what are the 2 types of solid state sensor (digital imaging)?
CCD charged-coupled device
CMOS complementary metal-oxide semiconductor
a CCD charged coupled device (solid state sensor - digital) has 4 layers.
front cover
scintillator layer
silicon wafer
back cover
what is the purpose of the scintillator layer?
converts x-rays to light
a CCD charged coupled device (solid state sensor - digital) has 4 layers.
front cover
scintillator layer
silicon wafer
back cover
what is the purpose of the silicone wafer?
converts the light into an electrical signal
a CCD charged coupled device (solid state sensor - digital) has 4 layers.
front cover
scintillator layer
silicon wafer
back cover with cable
what is the purpose of the back cover?
to carry signal to a PC can be wireless though
digital - solid state sensor - CCD
how does it work
X-rays hit ??, reaction gives off ?
? hits photosensitive cells in ??
? in each cell are released forming a ? through neighbouring cells which is converted to an ?
scintillator layer
light
light
silicon wafer
electrons
charge
image
digital - solid state sensor
Charged coupled device and complementary metal-oxide semiconductor work in a similar way.
what is the difference between CCD and CMOS?
Difference is each cell electrically isolated so signal is sent from individual cell not line of neighbouring cells
advantage of digital solid state sensors (CCD & CMOS) compared to phosphor plates
Resolution (detail) better that phosphor plates
what digital image system is used in DDH?
Photo-stimulable phosphor
digital - photo-stimulable phosphor
x-rays react with ? which stores radiation in local ? energies called the ?? -> ?? state
Plate scanned by ?? in vista scan unit causing electrons to ? to ??? by emitting ?? -> ?? state
Blue light is converted into an image using an ???? ADC
Plate ? by exposing phosphor to ??
phosphor
electron
latent image
stable excited
red laser
drop
lower energy levels
blue light
unstable excited
analogue to digital converter
erased
bright light
digital advantages over film 6
No chemicals
Faster processing times
Easy archiving - almost instant access to image
Easy image transfer - can send the image to anyone easily
Image manipulation - bigger, darker, lighter
Dose reduction
digital disadvantages to film 6
Expensive
easily damaged
Reduction in resolution due to pixel size and dose reduction
Archiving - back up, software issues, power-cuts etc
Easy image transfer - security concern
Image manipulation - incorrect diagnosis
what has caused the little variation in grey shades?
overexposure
what has caused the white mottling on image?
underexposure
not enough radiation hit the receptor
what is the archiving and communicating system used in DDH?
PACS
