arrt review: image production (CR v. direct DR v. indirect DR) Flashcards
CR plate layers in order
Protective
Phosphor (active) = PSP
Conductive
Support/base
Reflective (light shield)
Backing (“Protective backing”)
CR plate layers mnemonic
PPCSRB
People Prefer Chocolate Sauce, Really Bad
active component of the CR plate
PSP (phosphorstimuable phosphor)
____________ layer of CR plate grounds plate and reduces electrostatic charge
conductive
___________ layer of CR plate directs emitted light
Reflective (light shield)
PSP layer can ___________energy
store and release
material in CR plates
barium fluorohalide bromides and iodides with europium activators
material in DR indirect plates
amorphous silicon
material in DR direct plates
amorphous selenium
indirect DR steps (general)
x-rays –> visible light –> electronic signals
direct DR steps (general)
x-rays –> electronic signals
indirect DR
CCD versus TFT; what components make up the processing?
CCD = scintillation layer –> CCD –> ADC
TFT = scintillation layer –> photodiode –> TFT –> ADC
fill factor = ___________ of _______ devoted to the semiconductor detection layer
percent, DEL
higher DEL fill factor = (lower/higher) spatial resolution and (lower/higher) contrast resolution
higher, higher
direct DR layers
photoconductor –> TFT –> ADC
scintillation layer converts ______ to ______
x-rays to light
do direct DR systems use scintillation layers?
no (only indirect DR use scintillation layers)
scanning pattern of CR pattern
raster pattern
what is the color of the laser in CR processing?
red
what color light is emitted in CR processing?
blue or violet layer
what is the role of the photomultiplier?
Converts small amounts of light into an exemplified electrical signal
what does the analog to digital converter (ADC) do in CR processing?
converts the electrical signal from the photomultiplier tube into a digital signal
how is the CR plate erased?
bright white light
Slow scan = ______________________
fast scan = _________________
drive mechanism in the reader; movement of laser
some CR systems use _____ instead of photomultiplier tubes
charged coupled devices
CR processing energy transfer process = ______________________
photoelectric absorption
(smaller/bigger) DELs give you better spatial resolution
Smaller
Do we want a small matrix or a large matrix?
large matrix
most common matrix in x-ray
1024x1024
when you increase matrix size,
pixel size (increases/decreases)
spatial resolution (increases/decreases)
pixel size decreases, spatial resolution increases
Total number of possible brightness levels (shades of gray) that can be assign to the digital image
bit depth
is 12 bit or 16 bit preferred?
16 bit gives more shades of gray
Process of assigning brightness levels
quantization
larger bit depth increases ______________
contrast resolution
how does saturation appear?
black
how does mottle appear?
grainy
what is the definition of dynamic range?
range of exposures that can be captured by an image receptor
what is the definition of saturation?
intensity of radiation that is so high the computer cannot process it (beyond dynamic range of system)
what is the definition of exposure latitude?
range of exposures that can produce quality images at an appropriate patient dose
cesium iodide can be formed into _______ which focus (x-ray/light) photons
rods, light
Small DEL = (big/small) pixel = (high/low) spatial resolution
Small pixel
High spatial resolution
