RTE2457 Imaging II

  1. There are 2 types of Digital Radiography.
    1.__ __- Uses a photostimulable storage phosphor (PSP) inside a cassette.

    2.__ __- Uses a detector built in to Bucky or inside a cassette (wireless)
    1. Computed Radiography (CR)

    2. Digital Radiography (DR)
  2. Binary Machine Language

    Computers operate using a binary (base 2) system
    ____ = off
    ____ = on
    • 0 = off
    • 1 = on
  3. Each binary number is called a ___ “binary digit”
  4. _____ - a unit of data (word) that contains 8 bits. Also is the unit most computers use to represent a character such as a letter, number, or typographic symbol.
  5. _____ - A series of boxes displayed in a layout of rows & columns.

    ——- Each box is called a ___ that corresponds to a 2-dimensional location in the image (x & y coordinates)

    A _____ represents a 3-dimensional volume of tissue (z coordinate)
    • Matrix
    • Pixel
    • Voxel
  6. The ____(_) is the overall dimension of the image matrix.
    ——- is determined by the size of the detector in digital radiography.
    ——- if remains constant but matrix size increases, the pixels must get ____.
    • Field of View (FOV)
    • smaller
  7. Each pixel assigned a numeric value (_______) that represents a shade of gray or brightness level based on the attenuation characteristics of the volume of tissue x-rayed.
  8. Bone attenuates (absorbs) x-rays to a large degree, so the pixel value will be ___, producing high brightness. (Low density)
  9. Air attenuates x-rays to a lesser degree, so the  pixel value will be ____, producing low brightness (high density)
  10. High brightness = ___ density
    Low brightness = ___ density
    • Low
    • High
  11. ___ ___ is the number of bias used to represent each pixel. The greater the __ __, the more shades of gray that can be displayed.
    Bit depth
  12. ___ ___ refers to the range of values or number of gray shades that an imaging system can reproduce.
    Dynamic range
  13. The 3 types of Image Processing Operations
    • Point Processing
    • Local Processing
    • Geometric Processing
  14. ____ - a graphical display of the pixel intensity distribution for a digital image.
    - Is generated from the image data based on signal intensity from each pixel
    - The shape corresponds to the specific anatomy and technique used for an exam.
  15. On histogram 
    _-axis represents the amount of exposure
    _-axis represents the incidence of pixels for each exposure level
    • X-axis
    • Y-axis
  16. A computer analyzes the histogram to determine the ____ & _____.
    • Values of interest (VOI)
    • Exposure index number (indicator)
  17. A _____ is data stored in the computer used to manipulate the values of gray levels (contrast). It does this by substituting new values for each pixel during point processing.
    Look-up table (LUT)
  18. ___ ___ is why an underexposed or overexposed digital image may display with acceptable brightness on the monitor.
    Automatic rescaling
  19. ____ is a process that changes the contrast & brightness (density) of a digital image on the monitor. This is done through varying the numerical values of each pixel manually.
  20. The ____ ___ is the range of brightness (densities) that will be displayed on a monitor. It is primarily used to control image ____
    • Window Width (WW)
    • contrast
  21. The ____ ____ is the center of the window width, or the midpoint of the entire range of brightness (densities) displayed on a monitor. It is primarily used to control image ___.
    • Window level
    • brightness
  22. Narrow WW - ___ contrast
    Wide WW - ___ contrast

    Low window level - ___ brightness
    High window level - ___ brightness
    • High
    • Low

    • High
    • Low
  23. ____ ____ - is a process used to sharpen the image by amplification of the frequencies of the area of interest.
    Edge Enhancement
  24. ____ - is a process used to intentionally blur the image
    - low-pass filter applied
    - Produces an output image with decreased noise & brightness level of pixels
  25. ___ ___ - is a process used to subtract a low-pass (blurred) image from the original image
    - Suppresses some frequencies
    - Produces a sharper output image
    Unsharp masking
  26. ____ ____ - processes used to change the position or orientation of the pixels in the image
    Geometric Processing
  27. Factors that affect the quality of a digital image.
    ____ ___ - the degree of geometric sharpness of the structural lines (edges) recorded in the image.

    ____ - grainy or uneven appearance of an image

    ____ ___ ___ - a measure of the sensitivity & accuracy by which an image receptor converts the incoming data to the output device (monitor)
    Special resolution 


    Detective Quantum Efficiency (DQE)
  28. Spacial resolution 
    Small pixels = ____ spacial resolution
    Large pixels = ____ spacial resolution
    • Increased
    • decreased
  29. Noise

    ___ ___ ___ - results from undesirable signals from the digital system that do not contribute to the image.

    ___ ___ ___ - results from an insufficient quantity of photons reaching the IR (mAs and/or kV set too low)
    Electronic system noise

    Quantum mottle noise
  30. The ___ ___ is a comparison between the actual exposure & the proper exposure received by the IR.
    Deviation index
  31. PSP Plates
    ___ layer - base for the other layers 
    ___ layer - insulates plate from handling trauma
    ___ layer - active component of plate; holds photostimulable phosphors that are energized when exposed to x-rays
    ___ layer - grounds plate and absorbs light
    __ __ layer - prevents light from erasing data on plate
    ___ layer - prevents light leak
    • Support layer
    • Protective layer
    • Phosphor layer
    • Conductor layer
    • Light shield layer
    • Backing layer
  32. Indirect Flat Panel - uses ___ ___ as a scintillator that emits light when struck by x-rays
    —— ___ ___ transforms light into electronic signal
    • Cesium  iodide
    • Amorphous silicon
  33. Direct Flat Panel - no scintillator; uses ___ ___ to convert x-rays directly into an electronic signal
    Amorphous selenium
Card Set
RTE2457 Imaging II
Unit 1 Digital Radiography