Digital Radiography and PACS Chapters 1-3

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1. Digital Imaging

Any imaging acquisition process that produces an electronic image that can be viewed and manipulated on a computer

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2. Direct Capture digital Radiography

Devices convert the incident x-ray energy directly into an electrical signal. typically using a photo- conductor as the x-ray absorber, and send the electrical signal to a TFT and then to a ADC.

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3. Flat panel detector (FPD)

Detector that consists of a photoconductor, which holds a charge on its surface that can be read out by a thin-film transistor.

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4. Indirect capture digital radiography

Devices absorb x-rays and convert them into light. The light is then collected by an area-ccd or thin - film transistor (TFT) array and then converted into electrical signal that is sent.

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5. Photostimulable phosphor (PSP) Image capture

Digital acquisition modality that uses storage phosphor plates to produce projection images.

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6. Teleradiology

moving images via telephone lines to and from remote locations.

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7. Air Kerma

Kinetic energy released per unit mass; measures (in joules) radiation energy that is absorbed in unit of air.

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8. Brightness

Level of intensity of a digital image displayed monitor.

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9. Contrast resolution

ability of a digital system to display changes in grayscale values

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10. Detective quantum efficiency (DQE)

Measurement of how efficiently a system converts an x-ray input signal into a useful output image.

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11. Deviation index (DI)

The difference between actual exposure and target exposure expressed as a logarithm.

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12. Dynamic Range

The ability of an imaging system to respond to varying levels of exposure.

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13. Indicated equivalent air kerma (kind)

Measurement of radiation incident on the image receptor derived from pixel values produced by the exposure to an image receptor.

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14. Latitude

Amount of error that can be made in exposure factor choice and still result in capture of a quality image.

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15. Matrix

rectangular or square table of numbers that represent the pixel intensity to be displayed on the monitor.

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16. Modulation transfer function (MTF)

Ability of a system to record available spatial frequencies.

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17. Noise

Any type of signal interference in a digital image.

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18. Noise power spectrum (NPS)

Spatial frequency content and spatial characteristics of noise.

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19. Pixel

basic picture element on a display.

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20. Pixel bit depth

The number of bits within a pixel

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21. Signal-to-noise-ration (SNR)

The ratio of the amount of total signal versus the amount of noise present in any digital image.

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22. Spatial resolution

The ability of the imaging system to demonstrate small details of an object.

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23. Standardized radiation exposure (KSTD)

Standard exposure typical of an imaging receptor system that is made with additional filtration to simulate patient tissue.

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24. Target equivalent air kerma value (KTGT)

A set of established values that represent optimal exposure for each specific body part and view.

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25.Aliasing

Loss of digital information because of fluctuating signal; aka foldover, biasing, or wraparound.

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26. Archiving query

Software function that allows historical information to be gathered from digital storage, such as multiple exams, a range of dates, or pathology.

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27. Automatic rescaling

occurs when exposure is greater or less than the optimal amount to produce a diagnostic image; it is the effort of the computer to "fix" exposure errors.

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28. Contrast manipulation

conversion of the digital image using contrast enhancement parameters.

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29. Critical frequency

The frequency that exactly matches the Nyquist frequency resulting in a zero - amplitude signal caused by phase shift.

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30. Edge enhancement

Enhancement occurs when fewer pixels in the neighborhood are included in the signal average; the smaller the neighborhood, the greater the enhancement.

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31. High - pass filtering

technique for the enhancement of contrast and edge that amplifies the frequencies of areas of interest that are known and suppresses frequencies outside the area of interest.

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32. Histogram

Graphic representation of all digital recorded signals of a digital x-ray exposure.

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33. Image annotation

Software function that allows text or markers to be digitally added to an image.

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34. Image Orientation

Identification of the top or side of an image.

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35. Image Sampling

Amount of information gathered from pixel storage.

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36. Image stitching

the process of sewing together multiple images to form one continuous image.

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37. Look-up table (LUT)

reference histogram of the luminance values derived during image acquisition.

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38. Low-pass filtering

result of averaging each pxiel frequency with surronding pixels values to remove high-frequency noise and contrast; useful for viewing small structures such as fine bone.

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39. Manual send

computer function that allows images to be sent to specified reading stations.

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40. Nyquist theorem

When sampling a signal such as the conversion from an analog to digital image, the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect.

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41. Patient demographics

input information regarding patient age, identifying number, ordering physician, and so on.

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42. Shuttering

used ti blacken out the white collimation borders in a digital image, effectively eliminating veil glare.

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43. Smoothing

Aka low-pass filtering, the result of averaging each pixel's frequency with surrounding pixel values to remove high frequency noise.

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44. Spatial frequency

amount of detail or sharpness in a digital image.

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45. Window level

image manipulation parameter that changes screen image brightness, usually through the use of a mouse.

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46. Window width

image manipulation parameter that changes screen image contrast, usually through the use of a mouse.

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47. Which company was the first to introduce PSP imaging commercially in the US

Fuji

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

FPD

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49. When x-rays strike a photostimulable phosphor material ___ is released.

Light

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50. The exposure latitude of digital projection radiography responds in a linear or Nonliner

linear

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51. PACS stands for

Picture archiving and communication system

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52. In what format must images be in so that they can be sent throughout the image viewing system?

DICOM

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53. True or False: Patient demographics are unimportant because the RIS will automatically identify all digital images.

False

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54. True or False: Digitally placed anatomic markers can always be used to determine the correct anatomic side of the patient.

False

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55. Digital systems are less sensitive to scatter radiation than film/screen systems.

False

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56. An image formed by recording a continuously changing signal is known as

Analog

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57. The arrangement of pixels in rows and columns is known as

Matirx

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58. The amount of tissue included in the image is referred to as

Field of view

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59. Contrast resolution is a digital systems ability to?

show small differences in gray levels

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60. True or False: Dynamic range is the ability of a digital imaging system to respond to varying levels of exposure

True

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61. True or False: Spatial resolution in digital imaging is dependent on pixel size

True

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62. True or False: The best component in a digital system will determine the resolution in a digital image

False

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

DQE

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64. A graphical representation of a digital image is called

histogram

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65. The useful signal is determined during what part of the imaging processing?

Image sampling

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66. True or False: The Nyquist theorem states that the sampling frequency must be less than twice

False

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67. True or False: Aliasing occurs when the sampling frequency is not greater than twice the frequency of the input signal

True

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

Automatic rescaling

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69. True or False: The look-up table that is used to determine the brightness and contrast of an image is unique for each atomic part

True

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70. True or False: Window width controls brightness of the image on the display

False

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71. True or False: Shuttering the digital image will reduce the exposure to the patient.

False

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72. What processing parameter will put together multiple images into one single image for display?

Image Stitching