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Exposure & Imaging > Chapter 6 - Image Receptors & Acquisition > Flashcards

Chapter 6 - Image Receptors & Acquisition Flashcards

1
Q

4 steps for CR:

A

Expose
Stimulate
Read
Erase

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2
Q

Does CR or DR use barium fluorohalide crystals doped with europium for Photostimulable Phosphor (PSP)?

A

CR

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3
Q

After plate is exposed to X-rays, __% of metastable electrons relax (“expose”)

A

50

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4
Q

IP is put in plate reader & ____ _____ passes over remaining mestastable excited electrons to stabilize them. They give off ______ when they relax/stabilize (“stimulate”)

A

Neon laser

Light

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5
Q

Photomultiplier tube (PMT)

A

Collects light from IP & sends it to analog-to-digital converter (ADC) then to computer

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6
Q

Passes over IP to stabilize any remaining excited electrons & clear any remaining image

A

Intense white light

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7
Q

Exposed IPs should be processed within ______ because latent image starts to fade

A

1 hour

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8
Q

Spatial resolution is ____ with increased sampling frequency, increased number of smaller pixels, smaller pixel pitch, & smaller sampling pitch

A

Increased

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9
Q

Spatial resolution is increased with (4)…

A

Increased sampling frequency
Increased number of smaller pixels
Smaller pixel pitch
Smaller sampling pitch

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10
Q

CR plates can be read approximately ______ times before they need replaced

A

10,000

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11
Q

Combines image capture & readout so images are available almost instantly after exposure

A

DR (direct digital radiography)

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12
Q

True or false: DR is less expensive & fragile than CR

A

False. It is more expensive & fragile

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13
Q

Made with layers in order to receive X-ray photons & convert them to electrical charges for storage & readout

A

Flat panel detectors

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14
Q

The first layer of a flat panel detector is

A

X-ray converter

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15
Q

Thin film transistor (TFT) array which is divided into square detector elements (DELs), each with a CAPACITOR to store electrical charges & a switching transistor for readout to be sent to ADC

A

Second layer of flat panel detectors

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16
Q

DR systems (can or cannot) be permanently mounted in table/wall Bucky

A

Can

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17
Q

True or false: DR systems can be available as a mobile IR with “umbilical electrical cord” or wireless

A

True

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18
Q

What uses a scintillator like Cesium Iodide (CsI) or Gasolinium Oxyaulfide to convert exit radiation into visible light, which is converted to electrical charges by photodetectors

A

Indirect CR

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19
Q

Is indirect a 1 stage or 2 stage process?

A

2 stage

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20
Q

3 step process of Indirect (a-Si with CsI):

A

X-ray > light > electrical charge

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21
Q

Uses Amorphous Selenium (a-Se) to convert X-rays directly into electrical charges

A

Direct DR

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22
Q

2 steps of Direct process:

A

X-ray > electrical charge

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23
Q

Dynamic Range

A

Ability of detector to capture accurately the range of photon intensities exiting patient

24
Q

Digital IRs have much _____ exposure LATTITUDE than film-screen (analog)

A

Larger

25
Q

Image _____ occurs during post-processing to help produce images with appropriate grayscale appearance

A

Rescaling

26
Q

If IR is _________ quantum mottle/noise will result

A

Underexposed

27
Q

If the image is underexposed, the S number will be…

A

Too high

28
Q

If IR is _______, dose creep occurs

A

Overexposed

29
Q

If the image was overexposed, the S number will be….

A

Too low

30
Q

Increased signal-to-noise ratio (SNR) results in:

A

Improved image quality

Increased signal & decreased noise

31
Q

ALWAYS follow the ______ concept

A

ALARA

32
Q

Two types film screen systems

A

Regular cassettes

Extremity cassettes

33
Q

Duplitized or double-emulsion film

A

Regular cassette

34
Q

Single emulsion film

A

Extremity cassette

35
Q

Cassette that decreases patient dose with decreased detail (faster)

A

Regular

36
Q

Cassette that increases patient dose with increased detail (slower)

A

Extremity

37
Q

Film base

A

Polyester (usually tinted blue to decrease eye strain)

38
Q

Silver halide crystals suspended in gelatin

A

Film emulsion

39
Q

Super oat

A

Protects emulsion layer

40
Q

Theory that is most widely believed to explain latent image foundation on film

A

Gurney Mott

41
Q

Low scale, long contrast, wide latitude, many colors

A

High kV

42
Q

Decreased patient dose, increased scatter, good penetration

A

High kV

43
Q

Short scale, high contrast, narrow latitude, few colors

A

Low kV

44
Q

Increased patient dose, decreased scatter, poor penetration

A

Low kV

45
Q

Matching light sensitivity of film to color being given off by screen phosphors

A

Spectral matching

46
Q

Calcium tungstate color

A

Blue

47
Q

Rare earth color

A

Green

48
Q

Purpose of screens:

A

To INTENSIFY action of X-rays to decrease patient dose

49
Q

Faster screen=

A

Deceased detail

50
Q

_____ or ______ of screen is most important because it absorbs X-rays & converts them into light

A

Phosphor

Active layer

51
Q

_____% of density on a radiograph is from light

A

90-99%

52
Q

____% of density on a radiograph is from direct action of X-rays

A

1-10%

53
Q

5 INTRINSIC FACTORS that affect screen speed

A 
Phosphor size (large=fast)
Phosphor type (RE is faster than CT)
Active layer thickness (thicker=faster)
Reflective layer (faster)
Light absorbing dye (slower)
54
Q

EXTRINSIC factor affecting screen speed

A

KV (increased kV = faster)

55
Q

Double screen speed = cut mAs _____

A

In 1/2

56
Q

Cut screen speed in half = ___ mAs

A

Double

57
Q

Thin sheet of lead foil on back of cassette is to prevent

A

Backscatter

Exposure & Imaging (1 decks)

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