exposures exam

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exposures exam
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2010-04-01 16:02:45
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ch. 19-23
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  1. Photosensitive film
    sensitive to light & xrays

    most common
  2. Direct exposure film
    sensitive to xrays
  3. The base of the film is made up of _______ and what are the four properties?
    • Polyester
    • 1. flexible
    • 2. stable
    • 3. rigid
    • 4. uniformly lucent
  4. what is the purpose of the adhesive of the film?
    To glue the emulsion to the base
  5. Describe the emulsion of the film, and what does duplitized mean?
    • Made of gelatin w/ silver hallide crystals within
    • Duplitized = emulsion on both sides of film
  6. What is the most common silver hallide crystal?
    Bromide
  7. Supercoat of Film
    The protective layer of the film
  8. What is the sensitivity speck made of and what is its purpose?
    • Made of gold silver sulfide
    • Purpose: attract free silver ions moving around (to neutralize it)
  9. Panchromatic Film
    Sensitive to all colors of light
  10. Orthocrhomatic Film
    Sensitive to all colors of light BUT red
  11. Latent image
    The unseen change in atomic structure (during exposure)
  12. Gurney Mott Theory
    • 1. Incident photon knocks electron from Br- atom
    • 2. Ejected e- gets attracted to sensitivity speck, making it have a negative charge
    • 3. Negatively charged sensitivity speck attracks free roaming Br (silver) ions, neutralizing the speck...resetting the trap.
    • 4. 3 trapped silver atoms turns it to a black metallic silver (what makes film black)
  13. Direct Exposure film
    • Industry use
    • Only xray sensitive
  14. Screen Film, Photosensitive Film, Intensifying Screen Film-
    • sensitive to light & xrays
    • varies in film speeeeed
  15. Film Speed
    Amount of density a film produces for a given amount of exposure
  16. Film that is an exact copy of a radiograph and is already presolarized
    Duplication Film
  17. Presolarized
    Exposing the film up to the point of the reversal phase, can only become lighter
  18. what type of film is used for cerebral angiography?
    Subtraction Film
  19. Film should be stored______, at the temp of______, and _____ - _____ % humidity.
    • on end
    • 68 degrees F
    • 30-60 %
  20. The process of turning a latent image into a visible/ manifest image is called..
    Automatic Processing
  21. 4 steps of automatic processing
    • 1. developing
    • 2. fixing
    • 3. washing
    • 4. drying
  22. The reducing agent is part of the __________solution and consists of ______ and ______.
    • developer
    • Phenidone
    • Hydroquinone
  23. Phenidone provides ______ & ______ shades. It also works ______.
    • fine detail & gray
    • quickly
  24. Hydroquinone controls the _____, heavy shades of ______.
    • slow
    • black
  25. When P & Q work better together, its called?
    superadditivity
  26. Oxidize-
    Reduced-
    • reducing agent gives up electron
    • silver ion accepting an electron
  27. The more exposure = _____ black metallic silver atoms = _______ film
    • more
    • darker
  28. Activator (devloper)
    creates an alkine enviroment, which makes the reducing agent work
  29. Restrainer (developer)
    prevents reducing agents from over reacting/ keep darkening the film
  30. Preservative (developer)
    decreases oxidation of reducing agents when exposed to air (styrofoam)
  31. Hardener(developer&fixer)
    controls swelling of the gelatin
  32. Water (developer & fixer)
    SoLvEnT
  33. Fixer can't get into the developer due to the acidity of the fixer, if this would happen it would cause?
    contamination
  34. Clearing Agent
    • Fixer
    • Removes unexposed silver hallides from the film
  35. Activator (fixer)
    • maintain fixer acidity
    • makes the reducing agents stop working because of the low pH
  36. Preservative
    • fixer
    • keeps fixer from being exhausted
    • ammoniumthosilversulfate = ammoniumthiosulfate
    • takes silver out = silver recovery
  37. Archiving consists of 3 processes.
    • Washing- gets excess fixer & developer from film
    • Drying
    • Storage
  38. Too much fixer left on the film causes________ and is called _________.
    • film to be yellow
    • Fixer Retention
  39. Transport system consists of...
    • Rollers
    • Racks
    • motor driven
  40. volume replinishment
    • high # of flims going in/out of processor
    • replenished w/ each new film
  41. What type of replenishment system has.. low number of films, refills chemicals hourly, timer controlled, and helps with mixing new chemicals
    flood replenishment system
  42. Silver is found on ______ & ______. Its recovered by ____________________________
    • fixer and film
    • providing electrons to make black metallic silver
  43. What has more sliver, developed or undeveloped?
    undeveloped (x2)
  44. The measure of characteristic responses the film has to exposure & processing is called?
    sensitometry
  45. This device is made up of aluminum and provides a range of densities on a film. Two names..
    • Pentrometer
    • Step Wedge
  46. This device uses a light source, not an actual xray machine & is used to tell how well the processor is fucntioning.
    Sensitometer
  47. What is the function of a desitometer?
    To read the degree of blackening on a film
  48. Optical Density formula...
    • OD = log10 Io/ It
  49. Opacity formula and definition of ...
    • Opacity = Io/It
    • films ability to stop light
  50. Other names for D log E curve (3)
    • Characteristic
    • Sensitometric
    • Hurter & Driffield (H&D)
  51. B + F
    • Base + Fog
    • density of the film at no exposure
  52. Toe
    • phenidone
    • controls grays early on
  53. shoulder
    • hydroquinone
    • controls blacks later on
  54. Part of the curve where diagnostic info is found
    straight line portion
  55. Dmax
    • max. density the film is capable of recording
    • -all the silver hallides have all the silver atoms they can except
    • more exposure = less density
    • - called solarization
  56. Resolution is..
    • sharpness AND detail
    • bigger crystal size = less resolution
    • graininess = poor resolution
  57. The amount of density a film produces for a given amount of exposure is called..
    Film speed
  58. film speed is controlled by
    Speed goes up = patient does decreases
    phenidone (toe portion)
  59. large crystal size = high speed= decrease in resolution= less patient dose (T or F)
    thin emulsion = high speed= low resolution = less patient dose (T or F)
    • True
    • False (thick emulsion)
  60. Contrast in terms of the D log E curve is defined as
    slope of the straight line portion
  61. Average Gradient
    • straight line portion of D log E
    • (OD .25 + b + f & OD 2.5 + b + f)
    • what we can see
  62. The width of exposures that will produce densities in the diagnostic range.....
    • latittude
    • latittude increases = contrast decreases
  63. Device inside the cassette that contains phosphors that absorb xray photons & emit light photons
    1% xray, 99% light
    Intensifying Screen
  64. Emission of light from intenisifying screen when stimulated by radiation
    Luminescence
  65. good phosphors, only emit light when exposed to radiation
    fluorescence
  66. phosphors continue to clow after the exposure has stopped
    • Phosphorescence
    • AKA- screen lag, after glow
  67. What is considered the active layer of the intensifying screen
    phosphor layer
  68. what is the reflective layer of the intensifying screens job?
    to reflect light back towards the film
  69. single emulsion cassettes, what way does the film have to be placed in it?
    • emulsion side of film down on top of intensifying screen
    • creates less OID
  70. Calcium Tungstate intensifying screen
    old, glows blue
  71. Rare earth intensifying screen, why used today (3 things)
    • 1. greater absoprtion
    • 2. better resolution
    • 3. produces more light - glows blue & green
  72. Intensifying screen speed
    • capability of film to produce light
    • high screen speed= less patient dose ( high kVp, low mAs)
  73. Describe Quatum Mottle & what is the cure
    • occurs when too few photons form an image
    • less than 3 silver ions on sensitivity speck
    • salt & pepper apperance
    • Cure- high mAs, low kVp OR slower screen speed
  74. good film screen contact creates...
    • good resolution
    • no hair/dirt b/w film and intensifying screen
  75. Mwatching the color the phosphors of the screen glow to the sensitivity of the film is called...
    • spectral matching
    • spectral emission = color the screens glow
  76. Relative Speed
    RS # goes up = patient does goes down = resolution goes down = fast film screen combo = less latittude

    mAs1/mAs2=RS2/RS1
  77. What is line spread function?
    • LSF
    • measures the boundries
  78. what is modulation transfer function?
    • MTF
    • compares the detail
  79. Resolution...
    • lp/mm
    • 5 lp/mm is what we can see (dont get tricked, 10 lines= 5 line pairs)
  80. how is resolution limited?
    by the intensifying screen
  81. Hi..
    i'm disgusted with how many cards this turned into and i'm never typing them again. It gives my pinky a hinky feeling after I type too much.

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