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RAD 122 > Test 2 > Flashcards

Test 2 Flashcards

1
Q

Exact quantities

A

Digital

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2
Q

To go from analog to digital: assign __________ after ________ the analog curve

A

A numerical value (quantization)

Sampling

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3
Q

Sample at least twice; at least twice the frequency = good representation

A

Nyquist theory

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4
Q

⬆️matrix ️size _____ ️resolution

A

⬆️

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5
Q

⬆️pixels _____ ️resolution

A

⬆️

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6
Q

The assignment of 1’s and 0’s
0=
1=

A 
0= open
1= closed
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7
Q

The smallest unit

Single unit of data

A

Bit

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8
Q

1 byte =_____ bits

A

8

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9
Q

CR is ______ in its latent form

A

Analog

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10
Q

Where is the latent image stored in a PSP

A

In the phosphor layer

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11
Q

What are the phosphors made of in a PSP

A

Barium fluoro halides doped with europium

Halides can be iodine or bromide

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12
Q

What does CR eliminate from film screen system

A

Chemical processing

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13
Q

What happens to PSP when hit with xray

A

50% return to ground state immediately resulting in light (luminescence)
The other 50% is stored in phosphor crystals (losing signal over time must be read promptly)

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14
Q

T/F CR PSP is extremely sensitive to scatter radiation

A

True

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15
Q

How many shades of gray are found in digital CR image

A

10000

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16
Q

In the reader slow scan = _______

A

Mechanical drive

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17
Q

Fast scan =_______

A

Lasar row by row rastar scan function

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18
Q

_________ layer of PSP prevents backscatter from reaching the image

A

Reflective layer

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19
Q

What collects light and converts to an electric signal in reader

A

Photomultiplier tube

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20
Q

What is ADC

A

Analog to digital converter

Sampling and quantifization

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21
Q

What I the last step in reader before PSP is returned to case

A

PSP is flashed with a bright white light to release left over energy

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22
Q

What is ghosting

A

Left over image on PSP

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23
Q

CR advantages

A

Computerized image
Initially less expensive
Easy for mobile imaging

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24
Q

CR has ⬆️or⬇️contrast resolution than film

A

⬆️

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25
Disadvantage to CR
️decrease special ️resolution | Creep (ALARA)
26
Histogram errors may be caused by
Caddy cornering body part Random placement of body parts Selectin wrong body part on console
27
Histogram errors can result in
Improper rescaling of image Improper index # Improper masking
28
Continuously varying (clock with a second hand, latent image in CR and film)
Analog
29
Imaging plate layers from top to bottom (6)
``` Protective clear coat Phosphor layer Reflective/ protective Base Anti static Lead ```
30
Why are 3 main sub system components of CR reader
Mechanical components Optical components Computer modules
31
How is xray turned to light with DR indirect TFT
Indirect using scintillator with cesium iodide or gadolinium oxysulfide
32
What converts light into electrons in DR TFT flat panels
Photodiode amorphous silicon
33
TFT flat panels are considered
Active matrix array (AMA)
34
What turns xray into light with DR indirect CCD
Scintillator cesium iodide
35
How does light travel in DR CCD
In fiber optic bundles
36
What turns light into electrons in DR CCD
Multiple CCD photodiodes
37
Layers of CCD
Scintillator - cesium iodide Fiber optics Multiple CCD photodiodes
38
Layers of TFT
Scintillator - cesium iodide/ gadolinium oxysulfide Amorphous silicon - photodiode Pixel matrix with photodiode, storage capacitor and TFT switch
39
Number of shades of gray a pixel can represent
But depth
40
Using the laser to read the imaging plate, the laser is ________um in size and the narrower the beam _______ the ️resolution
100 | Better
41
Digital radiography was first introduced by
Fuji 1981
42
Computed radiography cassettes and film/screen cassettes can be used interchangeably t/f
True
43
Computed radiography screens respond to radiation with
Photostimuable luminescence
44
A photo stimulator phosphor in a metas table state will emit light
Immediately When stimulated Over time
45
Europium is the ______ if the photostimulable phosphur
Activator
46
The computed radiography cassette is called a ________ plate
Imaging
47
The photostimulable phosphur screen is handled in a _____
Reader
48
The computed radiography reader is made up of ______,_______, and ______ modules
Mechanical Optical Computer
49
The four steps of creating an image with computed radiography are
Metastable state, stimulate, read, and erase
50
Following the laser stimulation o the photostimulable phosphur the excited electrons are
Mostly stabilized
51
The digital imaging plate can sit for some time after the erase cycle
False
52
The laser is one of the ______ features of the computed radiography reader
Optical
53
Optical filters are used to filter out the _____ light an allow the_____ light to reach the photodetector
Stimulated, emitted
54
The output signal from the photostimulable phosphor plate is converted from analog to digital by the
Photodetector
55
Computed radiography and screen film imaging both have a
Latent image
56
Spatial resolution ️contrast ️resolution noise and artifacts are identical in screen film imaging an CR
False
57
The principal source o noise in CR is
Scatter
58
The 400 ️️speed film screen systems are still faster than computed radiography image receptors
False
59
With computed radiography the ️contrast is
Constant regardless of radiation exposure
60
The computed radiography image has
Wide exposure latitude and improved ️contrast ️resolution
61
When switching from screen film imaging to computed radiography which step is eliminated
Reloading the cassette and chemical processing
62
_________ is prevented by flooding the erased imaging plate with bright light
Ghosting
63
Computed radiography imaging produces ______ grey levels
10000
64
Switching from screen film imaging to computed radiography can ____ pt dose
Reduce

RAD 122 (3 decks)

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