DCR & DDR Flashcards
what are the layers of a CR plate/ IR
Protective Layer, phosphor layer, conductor layer, support layer, light shield layer, and backing layer
what is the protective layer?
keeps the plate safe from trauma
phosphor layer
contains the photostimulable phosphors/PSP
what is the usual components in the PSP
Barium fluorohalid with Europium or bromide and iodides with Europium
conductor layer
grounds the plate to eliminate electrostatic issue, and absorbs light to increase sharpness
support layer
the base on which to coat the other layers
light shild layer
prevents light from erasing data or leaking through the backing
Backing layer
made of lead and reduces back scatter which = high contrast
how does the CR imaging plate prevent the entire range of exposure to be digitized
the exposure data only processes the optimal density exposure range
how is the CR IR read
reads the image from the leading edge to the plate to the opposite end, it I displayed exactly how it was read and the reader must be informed father orientation of the anatomy
when should the anatomical part be selected when using a IRD?
Before the plate is put into the IRD
what is the first step of the Digital CR?
X-rays excite PSP outer shell electrons to a metastable state and when they return to ground state the emit a polychromatic light (blue)
what is the PSP in regards to what they do
it is the scintillator which absorbs X-ray energy and emits light.
what is the second thing that happens to the CR’s IR?
we place the IR in the IRD so ti can be read. where it is exposed to monochromatic light which speeds up the electrons process that brings the electrons back to ground state ( EMITS LIGHT)
what is the third step that happens to a CR’s IP?
the IP moves slow while the laser scans the plate fast.
what is the forth step what occurs in a CR’s IP?
coupling element transfers the generated signal and sends it to the collection element (photodetector) by Optic system and Optic filter,
what is Optic system
it is one of the components of coupling effect that picks up the phosphor’s emitted light and sends it to the photodetector
what is optical filter
it is one of the components of coupling element that makes sure it only picks up the wavelengths of the emitted signal from the phosphor and not the laser light signal
how is quantum noise created in CR
when a high kVp is used and a low mAs is used in order obtain an image, which creates the salt and pepper effect or density fluctuations
what happens if a IP is not placed in the IRD within 8 hrs
25% of data is lost
what is indirect capture, flat panel?
when an x-ray in DR goes from photon to scintillator to photodiode to TFT then to the computer
what is indirect capture, CCD
in DR where photon goes scintillator to lens then CCD then the computer
what is direct conversion, flat panel
in DR when photon goes to photoconductor then to the TFT then to the computer
what happens in a DDR indirect conversion flat panel detector signal chain? (in order)
X-ray tube>target>X-ray photons>scintillation layer> visible light photons>photo Diodes>Electrons>Amorphous silicon>TFT>Computer
First step in a DDR indirect conversion (flat panel/CCD)
two-step process: scintillator that captures X-rays and converts them to visible light. emits light isotropically and reduces spatial resolution.
second step in DDR indirect conversion (flat panel)
Photodetectors such as amorphous silicon photodiode array
third step in DDR indirect conversion (flat panel)
TFT thin-film transistor; Direct read out by sending it to the computer
second step in indirect conversion (CCD)
hits a lens
third step in indirect conversion (CCD)
CCD’s convert the light into an electric charge
4th step in indirect conversion (CCD)
electric charge goes from CCD to computer
what is a pixel in the Active Matrix Array (AMA)
each TFT and detector
what is DEL in the (AMA)
charge collecting detector element/TFT
other names for TFT
collecting element/ DEL detector element
how big is each TFT?
100 to 200 micrometers in size
how is the digital signal of the TFT read out
one pixel at a time
which systems are direct conversion?
Direct Ray; Hologic, kodak, Rockester, and NY
which systems are indirect conversion?
cannon CXDI-11, General Electric Medical Systems; Milwaukee, WI, and Trixell; Philips, Siemens, Thompson.
DCR’s sharpness
2-5 Ip/mm
Film screen’s sharpness
3-6 Ip/mm
DDR’s sharpness
3-5 Ip/mm
how do you adjust brightness level (density)
Window leveling
how do you adjust contrast
window width
high window leveling is what
narrow window width
low window leveling is what
wide window width
Exposure indicator
amount of radiation the IR receives
what is the Exposure Indicator for Fuji and Konica
Sensitivity (S)
what is the Exposure indicator for carestream (Kodak)
Exposure Index (EI)
Agfa
Log median value (lgM)
Gadolinium Oxysulfide
Indirect Capture
Direct capture photon conductor is made of
amorphous selenium
