1. Imaging Characteristics
Rad T 285 Review Topics 2
Imaging Characteristics

2. https://youtu.be/9G-mCRaPoRc

7. Signal-to-Noise Ratio (SNR)
A sensor responds to both signal strength and electronic errors from various sensor components (noise)
SNR = signal-to-noise ratio
signal = the actual energy reaching the detector
noise = random error in the measurement (all systematic noise has been removed)
To be effective, sensor must have high SNR

9. DQE

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Chapter 15
Computed Radiography
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12. Photostimulable Phosphor
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Image Noise
Mechanical Defects
Slow scan driver
Fast scan driver
Optical Defects
Laser intensity control
Scatter of stimulating beam
Light quanta emitted by screen
Light quanta collected
Computer Defects
Electronic noise
Inadequate sampling
Inadequate quantization
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Expose
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Stimulate
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Read
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Erase
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Chapter 16
Digital Radiography
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Digital Radiography
CR: photostimulable phosphor
SPR: photodiode
Indirect DR: thin-film transistor
Indirect DR: charge coupled device
Direct DR: thin-film transmitter
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21. Digital Radiography Imaging System
Capture Element
Coupling Element
Collection Element
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22. CsI Charge-Coupled Device (CCD)
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Capture Element CR
Photostimulable phosphor DR
Cesium iodide (CsI)
Gadolinium oxysulfide (GdOS)
Amorphous selenium (a-Se)
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Coupling Element
Lens
Fiber optic assembly
Contact layer
a-Se
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Collection Element
Photodiode: light-sensitive device
CCD: light-sensitive device
Thin-film transistor (TFT): charge-sensitive device—collects electrons
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32. Chapter 17 Digital Radiographic Technique
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33. Line Pairs and Spatial Frequency
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34. Spatial Resolution of Imaging Systems
Gamma camera
0.1 lp/mm
Magnetic resonance imaging
1.5 lp/mm
Computed tomography
Diagnostic ultrasound
2.0 lp/mm
Fluoroscopy
3.0 lp/mm
Digital radiography
Radiography
8.0 lp/mm
Mammography
12.0 lp/mm
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Dynamic Range
Screen-Film Imaging
OD zero to 3.0
Three orders of magnitude
Dynamic range = 1000
Digital Imaging
Bit capacity of each pixel
Four to five orders of magnitude
Dynamic range > 65,000
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37. MTF
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40. Bit Depth
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42. Contrast Detail(Resolution)
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45. The patient makes the beam better suited for absorption by the receptor
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