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RADT 171 - Phys. 2 > Digital Imaging > Flashcards

Digital Imaging Flashcards

1
Q

Two Step process for image capture and readout;
uses imaging plate (IP)

A

Computed radiography (CR)

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2
Q

Combined image capture and readout; uses flat panel detectors

A

Direct radiography (DR)

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3
Q

Individual picture elements in CR

A

Pixel

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4
Q

Matrix size in CR

A

Field of view (collimation)

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5
Q

_____ pixel size = better image quality in CR

A

smaller

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6
Q

Demonstrates exposure range (S number)

A

Exposure index

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7
Q

Two step process for CR

A

image capture and image readout

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8
Q

In CR, the image receptor houses the:

A

imaging plate (IP)

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9
Q

Absorbs x-rays in CR

A

IP phosphor

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10
Q

Converts latent image into electric signal that can be digitized

A

CR reader

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11
Q

3 stages on a CR reader:

A

scanning, sampling, quantization

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12
Q

Laser scanning of the exposed IP converts the ____ into an ______.

A

released energy (visible light); electrical signal (voltage)

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13
Q

The photodetector collects, amplifies, and converts the _____ to an _____ proportional to the range of energies stored in the IP

A

visible light; electrical signal

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14
Q

How often the analog signal is reproduced in its digitized form on CR imaging

A

Sampling frequency

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15
Q

Distance between sampling points on CR imaging

A

Sampling pitch

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16
Q

Each pixel brightness value on CR image is assigned a numerical number:

A

quantization

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17
Q

number of grey shades on CR image (contrast resolution)

A

Pixel depth

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18
Q

Integrated into the flat-panel device in DR

A

Signal storage, signal readout, digitizing electronics

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19
Q

Top layer of flat panel detector

A

X-ray converter

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20
Q

second layer of flat panel detector

A

TFT tray

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21
Q

third layer of flat panel detector

A

glass substrate

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22
Q

Two types of conversion that flat panel detectors use

A

indirect/direct

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23
Q

radiation to visible light, light to electrical charge, electric signal sent to ADC for digitization

A

Indirect conversion

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24
Q

Made up of rows/columns of individual pixels

A

Matrix

25
Q

number of bits; number of shades of gray

A

Pixel bit depth

26
Q

Every pixel value of an image would demonstrate the photo’s:

A

Histogram

27
Q

X-axis of an image’s histogram:

A

Pixel value

28
Q

Y-axis of an image’s histogram:

A

Pixel count

29
Q

Exposure histogram is compared to a:

A

reference histogram

30
Q

An image formed by recording a continuous changing signal is known as

A

Analog

31
Q

Which of the following measures the efficiency of a system to convert the x-ray input signal into a useful output image?

A

DQE

32
Q

The useful signal is determined during which part of the imaging cycle?

A

Image sampling

33
Q

In digital projection radiography, what process is used to normalize an image that has been taken with too great of an exposure?

A

Automatic rescaling

34
Q

Which processing technique will amplify particular known frequencies in an image while suppressing others?
a. Edge enhancement
b. High-pass filtering
c. Masking
d. All of the above.

A

D

35
Q

The active layer in a PSP plate is usually made of phosphors from what family group?

A

Barium fluorohalide

36
Q

What device in the reader detects the light being released from the PSP plate during reading?

A

Photodetector

37
Q

T/F: Dark line artifacts can be caused by too much kVp in an exposure.

A

True

38
Q

What does a photoconductor do?

A

absorbs x-rays and produces electrical charges.

39
Q

A charge-coupled device (CCD) does all of the following except:
a. Reduce the size of the projected light image
b. Transfer the image to a capacitor
c. Convert light into X-ray photons
d. Act as receptors via lenses or fiber optics

A

C

40
Q

T/F: Digital systems are more sensitive to scatter radiation

A

True

41
Q

What component of the CR reader converts light to an electric signal?

A

photodetector

42
Q

When x-rays strike the PSP material, ____ is released

A

Light

43
Q

T/F: The LUT is unique for each anatomic part

A

True

44
Q

Europium serves as:

A

An activator for the phosphor

45
Q

Two methods for indirect capture DR include:

A

Charged couple device
TFT arrays + scintillator

46
Q

DR converts x-rays into:

A

Electrons

47
Q

The scintillator for the indirect capture DR system using CCD that is made of

A

Cesium iodide

48
Q

T/F: After the digital data leaves the ADC, the process of image formation is very different for the 3 types of DR systems

A

False

49
Q

The ability of phosphors to emit visible light when exposed to x-rays

A

Fluorescence

50
Q

PSP stands for:

A

Photostimulable Phosphor

51
Q

Intensifying screens are used to:

A

Decrease patient exposure

52
Q

The type of image receptor (IR) that uses a photostimulable phosphor to acquire the latent image is ________________.

A

Computed radiography

53
Q

What is used to extract the latent image from an imaging plate (IP)?

A

Laser beam

54
Q

T/F: Digital imaging systems have a wide dynamic range.

A

True

55
Q

T/F: A 16-bit digital system would have a narrow dynamic range compared to a 12-bit system.

A

False

56
Q

What provides an indication of patient radiation risk during a radiographic procedure?

A

DAP and KAP

57
Q

Digital detectors that require a two-stage process to acquire and digitize the latent image include
A. flat-panel detectors indirect conversion.
B. CCD.
C. CMOS.
D. all the above.

A

D

58
Q

The exposure latitude of digital projection radiography responds in a _______ manner.

A

Linear

59
Q

Which radiographic image capture method uses an x-ray absorber material coupled to a thin film transistor or a charge-coupled device (CCD) to form the digital radiographic image?

A

FPD

RADT 171 - Phys. 2 (10 decks)

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