DR P2 Flashcards
digital radiography is more efficent in ____ ____ ____ then screenfilm
time
space
personnel
what is a CCD
charged coupled device
what does a CCD do
forms images from visible light
photon reaches a scintillation layer which coverts it to light
what is the CCD chip made of
crystalline silicon
what is etched onto the surface of CCD chips
the electronics which is the number of pixels
what happens when light hits the pixel
electrons are liberated and build up within it
the number of electrons liberated is proportional to the light intensity
why arent CCDs used for large fields of view
too many photons are lost
what is the role of the intensifying screen
convert photons to light
what is amorphous silicon
makes up the flat panel detectors
sensitive to light
what does the size of the detector element determine
spatial resolution of the detector system
smaller - higher SR
what is a DR image receptor composed of
capture element -aSi
capacitor -stores charge
thin film transistor (TFT) - charge sensitive, collects electrons
what is fill factor
ratio between light sensitive area and the area of the detector element
as the detector element gets smaller so does the….
light collection efficiency
smaller the detector element the greater the area that is occupied by electronics therefore less area is sensitive to light
high fill factor results in
most of the light photons contributing to the image
good result
low fill factor results in
loss of photons between the intensifying screen and detector element
therefore decreased contrast resolution and increased spatial resolution
