RAD-171 The prime Factors

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  1. what is APR
    anatomically programmed radiography
  2. what is AEC
    what does it control and what does it do
    • automatic exposure control
    • controls wall bucky and table
    • and they are sensors that control length of exposure and wait for predetermined radiation to hit it
  3. what factors affect our quality of the beam
    kVp and filtration
  4. what technical factors allow more interactions to occur
  5. what many factors affect our quantity
    • mAs
    • filtration
    • kvp SID collimation
    • certain body part
    • efficiency of the tube anode heel effect
    • certain pathology
  6. what are three factors that effect xray emission that is under control of the radiographer
    mAs kVp SID
  7. what happens when you double ma
    what happens to your image when you double mAs
    • double in the number of electrons crossing the tube
    • more dark
  8. what is mA
    measurement of tube current sent to the filament per second
  9. _____ and _____ are directly proportional to the # of xray created
    mA and time
  10. mA stations between 25-200 and 20-1200 use what size filament
    what will be the difference in your image
    • 25-200 small filament
    • 200-1200 large filament
    • same radiation but difference in detail
  11. what is the controlling factor of radiographic density/IR exposure
    mAs (milliamerage per second)
  12. In regards to film what is the degree of blackening on a radiograph
  13. what is IR exposure
    how many xrays interact with IR
  14. what increases as mAs increases and same applies as mAs decreases
    density/IR exposure
  15. When using film what happens if mAs is cut in half
    your image will appear two times lighter
  16. what is the reciprocity law
    what whens when mAs is constant
    List examples
    law that states the density on an xray film/IR exposure is proportional to the intensity and duration of the xray exposure

    as long as the ma is constant any combination of mAand exposure time(s) will create the same density/IR exposure

    • Ex.200 mA x .1 = 20mAs
    • 100 mA x.05=20mA
  17. what is brightness
    how dark or light digital image appears on monitor
  18. If your original film was acceptable (okay) what would you to view small differences on film
    increase by mas 30%
  19. what is the primary controller of density/IR exposure
    and what decreases as radiographic density/IR exposure decreases
    mas (both)
  20. what happens to your image is mas is double or cut in half on film
    • mas double = twice as dark
    • mas is cut in half = twice as light
  21. what is density
    • traditional term for infrared (IR) exposure to film
    • it is the amt of silver deposited on hard copy film image
  22. what does it mean if your exposure numbers are over or below the index (svalue) range
    it means the image was under exposed or over exposed
  23. what is the direct square law pertaining to mas
    what is the formula
    • it means it has a direct relationship necessary to compensate for the change in intensity and IR exposure
    • mAs 1 over mas2 = distance a squared over distance 2 squared
  24. explain direct square law in your own words
    • if you double the distance you are going to need 4x more mas or radiaition
    • if you cut the distance in half you will 4x less radiaiton
  25. maintaing a certain amount of density meanas we are maintaining a certain amount of _____
  26. when in doubt about choosing if an image is too dark or too light the best option would be too ________
    but what is the cost of doing this
    • over expose the patient
    • cost the patients recieving more radiaition than needed
  27. what is the one factor that affects certain use of mA
  28. if 10 mAs were used with a 40'' SID, what new mAs would be needed to maintain density if the SID was changed to 80''
    40 mAs since the distance was doubled you have to increase the mAs by 4x more
  29. what unit of measurement is the inverse square law measured in
    roentgen or mR
  30. what is the inverse square law (brief definition)
    intensity of radiation is inversely related to square of distance between object and source
  31. what is contrast
    the differentiation betwe the shades of gray
  32. if an image is very gray and murky what contrast is it ?
    low contrast
  33. what does kVp control
    what does it affect
    how does kvp pertain to the body
    • both the quantity and quality of the xray beam
    • radiographic contrast
    • it shows how much we can absorb
  34. what two things does kVp cause pertaining to the electrons when increased
    increase in speed of electrons and the energy of the electrons applied across the tube
  35. why is beam quantity affected when dealing with kVp
    high kVp causes more interactions at the target
  36. why is beam quality affected
    each electron has more energy, resulting in a beam with greater penetrability
  37. what ability does the xray energy have once kVp increases
  38. when do we need an increase of kVp
    • when dealing with larger patients
    • certain pathologies
    • or through casts
  39. what percentage of increase or decrease in kvp will happen if double the mas or reduce the mas in half
    • if mas doubles kvp decrease by 15%
    • if mas is cut in half it is increase by 15%
  40. what is the controlling factor and main influencing factor of radiographic density/IR exposure
  41. List all the factors of a High contrast image
    what is the alternative name for a high contrast image
    • extremely white,
    • few shades of gray
    • low kvp more absoprtion

    the image is short scaled or increased contrast
  42. list all factors for a low contrast image
    what is the alternative name for a low contrast image
    • flat murky color
    • lots of shades of gray
    • happens with high kVp
    • increase of scatter radiation

    the image is decreased or long scaled contrast
  43. use 15% rule for this:
    10 mAs & 80 kVp
    find the new values for short scale, increased contrast
    and long scale decreased contrast
    • short scale: 20 mas & 68 kvp
    • long scale: 5 mas & 92 kvp
  44. an ________ in kvp will decrease contrast and a _______ in kvp will increase contrast
    • increase
    • decrease
  45. High contrast image has high or low kvp
    low contrast image has high or low kvp
    • low
    • high
  46. with digital and image receptor systems what is controlled through post processing
    density and contrast
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RAD-171 The prime Factors
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