physics 2. ch 23. digital/ midterm Flashcards
two types of digital ?
CR and DR
converts X rays (photons) to visible light
scintillator
converts light photons into electrons. used in direct DR
photodetector
does direct DR use a scintillator
no
uses only a photodetector and TFT
Direct
a rigid sheet with several layers designed to record and enhance transmission of the image from an X Ray beam
PSP
contains the standard contrast, speed and latitude for an exam
LUT. look up table
where are DELs found
in the TFT
true or false?
CR systems are INDIRECT radiography with INDIRECT acquisition
true
flat panel detectors are both ______ and ______
indirect and direct. both use TFTs
A series of boxes laid out in the rows and columns that gives form to an image
matrix
what determines the FOV field of view?
size of the detector
what determines the number of shades of gray?
bit depth
what is the digital standard for imaging
DICOM
why is DR indirect considered a two step process.
X rays are converted to light first. then an electronic signal is created
DR direct system has better resolution. why?
there are fewer conversion steps. X-rays go straight to an electronic signal with no light conversion in direct systems
an electronic signal collector of electrical charges
TFT
in what type of system is a high-voltage charge applied to the top surface of the selenium layer
DIRECT DR
where would you find cesium iodide?
scintillator
a photo diode is a light collector. name one:
amorphous silicon
direct DR uses a photoconductor instead of a photodiode. it doesn’t use light as a separate step like indirect. it’s called ______ ______
amorphous selenium
