Chapter 21

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vheipl01
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44879
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Chapter 21
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2010-10-25 19:59:03
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General Imaging
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General Imaging
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  1. Sensitometry
    the measurement of the characteristic responses of film to exposure and processing
  2. The measurement of the characteristic responses of film to exposure and processing
    Sensitometry
  3. penetrometer
    a device with a series of increasingly thick uniform absorbers used in teh monitoring of x-ray equipment, film, and film/speed combinations (step wedge)
  4. a device with a series of increasingly thick uniform absorbers used in the monitoring of x-ray equipment, film, and film/screen combinations (step wedge)
    penetrometer
  5. a device used to expose a reproducible, uniform, optical step wedge onto a film used for processor monitoring or film comparison
    senistometer
  6. sensitometer
    a device used to expose a reproducible, unform, optical step wedge onto a film used for processor monitoring of film comparison
  7. densitometer
    and instrument that provides a readout of the amount of density (blackening) on a film
  8. an instrument that provides a readout of the amount of density (blackening) on a film
    densitometer
  9. optical density
    the density viewed on an x-ray film
  10. the density viewed on an x-ray film
    optical density
  11. optical density is determined by what formula?
    • OD= log10 Io/It
    • Io= intensity of incident light
    • It= intensity of the transmitted light
  12. opacity
    the ability of the film to stop light
  13. the ability of the film to stop light
    opacity
  14. what is the opacity formula?
    Io/It
  15. the D log E curve, or H&D curve, or characteristic curve, or the sensitometric curve
    a graph of the relationship between hte amount of exposure and the resultant density on the film
  16. a graph of the relationship between the amount of exposure and the resultant density on the film
    the D log E curve, or H&D curve, or characteristic curve, or the sensitometric curve
  17. base plus fog
    the density inherent in the film and the fog that is produced by processing (no exposure)
  18. the density inherent in the film base and the fog that is produced by the processing (no exposure)
    base plus fog
  19. toe
    subtle gray tones in early development mostly controlled by phenidone
  20. suble gray tones in early development mostly controlled by phenidone
    toe
  21. straight line portion
    between toe and shoulder - most of the diagnostic quality information is on this portion of the curve between OD .5 and 1.25
  22. between toe and shoulder - most of the diagnostic quality information is on this portion of the curve between OD .5 and 1.25
    shoulder
  23. Dmax
    maximum density the film is capable of recording. Any exposure above this will result in less density (reversal or solarization)
  24. maximum density the film is capable of recording. Any exposure above this will result in less density (reversal or solarization)
    Dmax
  25. film characteristics
    resolution, speed, contrast, latitude
  26. resolution, speed, contrast, latitude
    film characteristics
  27. resolution
    not analysed by sensitometry, the ability to accurately image an object also called detail, sharpness, definition, or resolving power, measure by the ability to see line pairs - unit of resolution is liine pairs per millimeter expressed as lp/mm
  28. not analysed by sensitometry, the ability to accurately image an object also called detail, sharpness, definition, or resolving power, measure by the ability to see line pairs - unit of resolution is liine pairs per millimeter expressed as lp/mm
    Resolution
  29. resolution is determined by (2)
    • 1. size of silver halide crystals - inverse relationship: larger crystal the lower resolution, smaller crystal the higher the resolution
    • 2. usually controlled by the size of the intensifying screen crystals
  30. speed
    the amount of density a film produces for a given amount of exposure controlled by phenidone because this affects the toe of the D log E curve and thus when the straight line portion of the curve begins. Determined by the size of the silver halide crystals and the number of sensitivity specks and the thickness of the emulsion
  31. the amount of density a film produces for a given amount of exposure controlled by phenidone because this affects the toe of the D log E curve and thus when the straight line portion of the curve begins. Determined by the size of the silver halide crystals and the number of sensitivity specks and the thickness of the emulsion
    speed
  32. speed point or speed exposure point
    density of the DO 1.0 + b+f on the curve
  33. density of the OD 1.0 + b+f on the curve
    speed point or speed exposure point
  34. Difference in film speed formula
    • antilog (log E1 - log E2)
    • log E1 is the log exposure of the 1st film
    • log E2 is the log exposure of hte 2nd film (see page 321 + 322)
  35. relative speed formula
    1/ exposure in R needed to produce speed point density (OD 1.0 + b+f)
  36. speed is affected by
    immersion time, temperature, and chemical activity
  37. immersion time, temperature, and chemical activity affect what?
    speed
  38. contrast
    the difference between adjacent densities
  39. the difference between adjacent densities
    contrast
  40. density will only affect contrast when ___ or ___ the ___ ___ ___ or hte curve
    above, below, straight line portion
  41. what will only affect contrast whe above or below the straight line portion of the curve
    density
  42. the slope of any portion of the D log E curve
    Gradient point
  43. Gradient point
    the slope of any portion of the D log E curve
  44. Average Gradient
    overall radiographic film contrast
  45. overall radiographic film contrast
    average gradient
  46. average gradient formula
    • D2 - D1 / E2 - E1
    • D = a constant of 2.25
    • e= the exposure that produces D
  47. latitude
    the range of exposures that will produce densities within the diagnostic range - between .25 and 2.50
  48. the range of exposures that will produce densities within the diagnostic range - between .25 and 2.5 (I thought it was 2.25...)
    latitude
  49. latitude formula:
    • Eh - El
    • Eh = high point
    • El = low point
  50. latitude and contrast are ___ related, as contrast ___, latitude ___. As contrast ___, latitude ___.
    inversely, increases, decreases, decreases, increases

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