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RT 265 Digital Radiography
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What is a Pixel?
(picture element) This is the Basic component of the digital image; What we see in 2D
What is a Voxel?
Volume Element
. This is the
3D
element that includes
Depth.
The pixel is essentially the End of the Voxel
Voxel is the ------- of the patient?
Thickness of the patient
Is Voxel controlable in CR or DR?
No... its fixed in CR and DR
With large patients =Poor image
vs
Small patietn= better image
What is a Matrix?
The
ACTUAL Image we SEE
is
made up
of a
series
of
Pixels
in Rows & Colums called a
Matrix
What is a
BIT?
A BIT is the amount of
GRAY SCALE
in the image. (Contrast) More bits=more shades of gray
(bit is the exponenet to TWO)
2Bit is two to the second or four
2squared 2(2) = 4 shades of gray displayed
Today most image are 10 to 12 Bits
What is FoV?
Field of View.
How much anatomy is Displayed
12cm FoV display 12cm of anatomy on the screen
The Smaller FoV= More Magnified Anatomy
Small FoV = Better or Worse Spatial resolution
(This is true for all modalities Except for DR)
Smaller FoV= Better Spatial Resolution
but, image will appear larger
8x10= sharper image vs 14x17=less sharp
Singal=
Singal =Photons
Noise=
Noise= Scatter radiation
Window Width
The GRAY SCALE of the digital image.
Larger Window width=
More or less grays scales?
Larger Window Width= MORE Gray scales=Lower contrast
(narrow Width= fewer gray scales-shades of gray)= Higher contrast
Window Level=
Window Level is the DENSITY or BRightness of the image.
The Higher the number the Brighter the image
What is the Photoconductor made up of?
Amorphous Selenium
-->captures x-ray photon & generates a signal
Inderect (CR) Intensifying Screen is made up of?
Cesium-iodide crystals & the Photocondector is made up of Amorphous silicon
What are the Elements of DRD Imaging system
1. Capture Element-to capture x-ray photon
2. Coupling element-Transfers x-ray generated signal to the collection element
3. Collection Element- Photodiode, CCD, TFT, CMOS-(light sensitive devices that collect light photons)
TFT-collect Electrons
Author
Anonymous
ID
168265
Card Set
RT 265 Digital Radiography
Description
RT 265 Digital lecture 1 Fall 2012
Updated
9/10/2012, 1:21:21 AM
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