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Medical Imaging- Nicole Calvin > Digital Imaging > Flashcards

Digital Imaging Flashcards

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USMLE® Step 1 flashcards
1
Q

A Digital Image is made up of what?

A

Matrix- Rows and Columns

Pixel- The little boxes within

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2
Q

(Digital Image Characteristics)

  • Stored as digital date
  • Must be processed by a computer for viewing on a display monitor
A

Latent Image

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3
Q

What are two types of digital radiographic systems?

A
  • Computed Radiography (CR)

* Direct Radiography (DR)

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4
Q

________ resolution refers to the smallest object that can be detected in an image?

A

Spatial

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5
Q

Picture archival and communication system; consists of digital acquisition, display workstations and storage devices interconnected through a network

A

PACS

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6
Q

Digital imaging and communications in medicine; standards that allow imaging modalities and and PACS to communicate the same “language”

A

DICOM

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7
Q

A network that connects computers locally across short distances, for example within a building or complex

A

LAN

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8
Q

A computer network that extends over a larger area, which can include global coverage

A

WAN

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9
Q

Hospital information system; hold patients full medical information from hospital billing to inpatient ordering

A

HIS

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10
Q

Radiology information system; holds all radiology specific date, including patient scheduling

A

RIS

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11
Q

Failure of an imaging system to record densities usually caused by lack of x–ray photons

A

Quantum Mottle/Noise

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12
Q

FOV

A

Filed of View

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13
Q

What happens if you increase the number of pixels when you print an image

A

It improves spatial resolution, however it increases computer processing time, network transmission time and digital store space.

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14
Q

(Digital Image Characteristics)

Digital Image- can be manipulated by computer

A
  • Alter brightness
  • Change Contrast
    (Matrix- rows and columns, Pixels- picture element)
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15
Q

FOV- Field View

A

Dimensions of an anatomic area

Digital quality improved with larger matrix size

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16
Q

What is directly related to FOV?

A

Pixel Size

Ex; increasing the field of view for the SAME MATRIX will increase the size of the pixel- decrease spatial resolution

17
Q

What is Inversely related to matrix size?

A

Pixel Size
Ex; increasing the matrix size for the SAME Field of View will decrease the size of the pixel- this will increase spatial resolution

18
Q

The pixel spacing or distance measured from the center of a pixel to an adjacent pixel

A

Pixel Pitch

19
Q

A greater number of pixels per unit area

A

Pixel Density

20
Q

What are two types of digital image receptors?

A 
Computed radiography (CR)
Direct Radiography (DR)
21
Q
  • Combines image capture & image readout process
  • Images are available almost instantly after exposure
  • DR receptors are more fragile & expensive than CR IRs
A

Direct Radiography

22
Q

Pixels

A
  • Increasing pixel density and decreasing pixel pitch increases spatial resolution
  • Decreasing pixel density and increasing pixel pitch decreases spatial resolution
23
Q

Computed Radiography Image Receptors (CR IRs)

A
  • Portable or fixed in a table

* Includes a cassette that houses the imaging plate

24
Q

What are the two step process for image acquisition in Computed Radiography Image

A

1) Image Capture in the imaging plate
2) Image readout
(longer delay between image capture and image readout)

25
Q

Digital Image vs. Computer Image

A
  • The detector system is usually dedicated to a single room and can be permanently mounted
  • Flat panel detectors are also mobile IRs and can be removed from Bucky and used on table top
  • After exposure digital image is available within milliseconds on viewing monitor
  • Flat panel system are highly dose efficient and provide quicker access to images
  • The spatial resolution of flat panel receptors is general superior to that of CR
26
Q

A digital composite of the varying x-ray intensities exiting the patient

A

Image Matrix

27
Q

What happens to an x-ray when the intensities are converted to numeric data?

A

The digital image can be electronically processed, manipulated, transported or stored.

28
Q

Computer software operations available to you that allow manual manipulation of the displayed image

A

Post-processing

29
Q

Sets the midpoint of the range of brightness visible in the image

A

Window level

30
Q

A control that adjusts the radiographic contrast-

A

Window width
(Narrow) increases the image contrast
(Wide) decreases the image brightness

31
Q

An image-processing technique commonly used to asses the raw data prior to image display

A

Histogram Analysis

32
Q

True of False: Does digital IRs have a much wider dynamic range than film screen detectors?

A

True- small degree of under or overexposure is okay

33
Q

True of False: Too low or too high exposure techniques guarantee a quality digital image?

A

False: It is NOT guaranteed

34
Q

Represents the number of digital pixel values versus the relative prevalence of those values in the latent image

A

Histogram

  • amount of exposure is on the x-axis
  • the incidence of pixels is on the y-axis

Medical Imaging- Nicole Calvin (9 decks)

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