CR And DR Flashcards
Bit
Single unit of data (0 white or 1 black)
Total number of bits in a byte system
8
Bit depth
- Number of gray shades
- 2^n total possible number of coloration
What are the total number of bit values
2
What is the main controlling factor of greyscale/contrast
LUT
What is the imaging plate used in a CR system known as
PSP
What are the phosphors made of used in PSP plate
Barium fluorohalide
Latent image
Invisible image, electronic image made of valence electrons stored in high energy traps
Manifest image
Visible image, made by exposure to a very small beam from a high energy laser
Imaging plate reader
-employs laser that reads the energy stored in the conductive layer, causing light to be emitted that is amplified by the photomultiplier
Fast scan
Raster pattern movement of the laser across the PSP plate
Slow scan
Mechanical movement of the PSP plate into the CR reader
S (sensitivity numbers)
Have an inverse or indirect relationship to the amount of exposure
EI (exposure index)
A direct relationship to the amount of exposure
lgM (logarithm of the median exposure)
A direct relationship to the amount of exposure
Indirect uses what material
Cesium iodide (CsI) or gadolinium oxysulfide
What is the device used to convert x-rays to light in an indirect capture system
Scintillator
What is the photoconductive material in indirect system made of
- amorphous silicon
- used to convert light photons into electrons, light is imaged onto a CCD
CCD requires what to produce light
Scintillator material, indirect form of image capture
Light from the scintillator strikes _____ to convert it into an electrical signal
CCD
TFT arrays absorb xray photons and convert them into what
Electrical signals using amorphous silicon (TFT panel)
Direst 2 step process uses what as the image receptor
Active matrix array (a-Se w/ TFT)
Direct system uses what material
Amorphous selenium, converts xray beam into electrons that are collected by the TFT
