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Rad Physics > Exam 2 > Flashcards

Exam 2 Flashcards

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0
Q

how many lines per inch are recommended for a stationary grid?

A

10-12

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1
Q

to increase the density of a film by using mAs what would you do?

A

increase mAs by 100% (double it)

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2
Q

when converting from low ratio to high ratio grid what would be the best to do to maintain good film quality?

A

increase mAs (could increase kv also, but mAs increase decreases scatter

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3
Q

if a film is burned out it is said to be?

A

too dark

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4
Q

why would a fixed kv technique be preferred?

A

contrast is consistent

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5
Q

what would produce the least amount of grid lines?

A

a moving grid

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6
Q

exceeding the optimal kv range while maintaining good density would yeild a film that has?

A

a long scale contrast

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7
Q

remnant radiation refers to what?

A

scatter rays the leave the patient and reach the grid, and primary rays that leave the patient and reach the grid

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8
Q

a a general rule when you xray an elderly patient what should you do to your established radiographic technique?

A

decrease it

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9
Q

what increases patient exposure?

A

increased mAs

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10
Q

if you took a lateral cervical with 66kv, 100mAs, 1 10th of a sec, at 72” FFD and it was too light but you could see structures what would you change to retake the film?

A

increase kv by 15%

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11
Q

how much mAs increase is required when you go from a non grid to a 12:1 grid technique?

A

5 times

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12
Q

in an ap lumbar film on a thin patient using 85 kv at 100 mAs with an exposure time of 1/2 a sec and you could see the structures but the film was too light how would you get a better film?

A

double mAs

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13
Q

if you took a 14 x 17 lateral lumbar film and saw the L5-S1 area was too light what would be the best thing to do?

A

take a 8 x 10 spot lateral and increase the mAs by 60%

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14
Q

if you saw a blood vessel axially on a chest film what density would it look like on film?

A

water

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15
Q

if you saw two structures with paralleling tracks of calcification overlying the articular pillars diverging superior and converging inferior, what would you be looking at?

A

part of the thyroid cartilage

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16
Q

how would you fix a grey film that you can still see structures?

A

double the mAs and decrease the kv by 15%

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17
Q

if you took a lateral cervical at 65 kv, and 10mAs without a grid and the film was too light but you can still see structures how would you fix it?

A

increase kv by 15%

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18
Q 
if you took a series of ap lumbar films at different settings which would have to lowest contrast?
95 kv, 6.25 mAs
106 kv, 3.75 mAs
58 kv, 60 mAs
85 kv, 8 mAs
A

106 kv and 3.75 mAs (long scale, wide exposure)

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19
Q

if you didn’t use a grid for an ap lumbar film and adjusted the technique to maintain a good density what would be the outcome?

A

the film would be very grey

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20
Q

how would you double the density of a film using kv?

A

increase kv by 15%

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21
Q

if you compared two cervical films one taken at 40” and the other at 72” what difference would you see?

A

the image on the 72” film would be smaller and clearer

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22
Q

what would be a problem if the xray tube shifted laterally from the center of the film?

A

shape distortion

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23
Q

what is the primary purpose of a grid?

A

to reduce scatter radiation to the film

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24
Q

what increases comptons radiation?

A

higher kvp

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25
Q

what term is used when comparing the height of absorbing strips to the width of the interspacing material of a grid?

A

grid ratio

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26
Q

what is the recommended optimal kv range for an ap lumbar film?

A

80-90

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27
Q

when looking for a grid which interspacing material would you want for xraying the spine?

A

aluminium

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28
Q

what best describes back scatter?

A

scatter that is directly toward the tube

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29
Q

if you wanted to alter the film so it had more grey tones what would you do?

A

increase kv

30
Q

what affect does a reciprocating grid have that a stationary grid does not?

A

it blurs out grid lines

31
Q

what is recommended for a spinal film when using a stationary grid?

A

a 10:1 grid ratio

32
Q

if you xray an elderly patient what should you do to your established radiographic technique?

A

decrease it

33
Q

contrast between structures of different subject densities is due to which of the following?

A

differential absorption

34
Q 
which exposure technique would have the lowest contrast?
200 mas, 75 kvp
150 mas, 65 kvp
100 mas, 95 kvp
50 mas, 110 kvp
A

50 mas, 110 kvp (decreased contrast = increased kvp)

35
Q

what best describes the effect that scatter radiation has on a film?

A

it causes greying of the film

36
Q 
which radiographic technique would demonstrate the most film grain?
70 kv, 25 mas, for 1 sec
80 kv, 50 mas, for 1/2 sec
90 kv, 100 mas, 1/4 sec
100 kv, 200 mas, for 1/8 sec
A

100 kv, 200mas, for 1/8 sec

37
Q

the ________ is the main function of mAs

A

film density

38
Q

if you cannot see structures because the film is too light what would you do to retake?

A

double mAs and increase kv by 15%

39
Q

if you took a lateral cervical at 66 kv and 100 mas and you could see structures but the film was too light what would you do to retake it?

A

increase kv by 15%

40
Q

what would most likely produce a film with the most visible grain?

A

a high kvp/low mas film

41
Q 
which scenario would provide the darkest film?
75 kv 14 mas
65 kv 14 mas
85 kv 14 mas
95 kv 14 mas
A

95 kv 14 mas (increased kv = increades overexposure)

42
Q

how much increase in mas is needed to maintain same density when reducing the xray field from 14 x 17 to 8 x 10?

A

60%

43
Q

what is not true about an xray beam?

A

the more peripheral parts of the beam causes less distortion

44
Q

what are the optimal kv ranges?

A

cervical 75 - 85
ap lumbar 80 - 90
thoracic 85 - 95
full spine 80 - 100

45
Q

a film exposed to secondary radiation will have what appearance?

A

it greys the film making it dark

46
Q

what would result in an increase in the amount of xrays passing through the patient without interaction?

A

higher kv

47
Q

what is the main reason that a fixed kv technique is preferred?

A

contrast is consistent

48
Q

a film that is lighter on one side than the other would indicate?

A

grid cutoff

49
Q

a lateral cervical film could use what that a lateral thoracic or lumbar shouldn’t?

A

an air gap

50
Q

what decreases contrast?

A

decreased kv = decreased contrast

51
Q

if you are xraying a young female for scoliosis what view would you use to see thoracic and lumbar segments while taking into account her breast tissue and gonads?

A

full spine with the patient facing the film

52
Q

what anatomy in a 72 year old patient would most likely absorb the most xrays in a lumbar and pelvic film?

A

osteoperotic pelvis

53
Q

what is the maximum recommended kv for an 8:1 grid?

A

90 kv

54
Q

if you wanted to alter the contrast of your film so there were more grey tones what would you increase?

A

kv

55
Q

what refers to an attenuation of part of the beam by the grid?

A

grid cutoff

56
Q

what produces the lowest scale of contrast?

A

wide range between kv and mas

57
Q

what would increase patient exposure?

A

using a 10:1 stationary grid

58
Q

what is the result of decreasing mas by 1/2?

A

film density would be decreased?

59
Q

what would cause a decrease in subject density?

A

disuse atrophy?

60
Q

what could be a problem if your xray tube was laterally shifted from the center of the film?

A

shape distortion

61
Q

the height of a grids lead strips compared to the width between them is called what?

A

grid ratio

62
Q

too high of a kv will have which effect on the film?

A

quantum mottle

63
Q

what is the relationship between kv and mas?

A

50% decrease in mas is equal to 15% decrease in kv

64
Q

a lateral lumbar film taken at 90 kv and 100 mas and the image was too light but you could see structures what should you do to retake image?

A

double mas (not kv because the value is already in optimal range for lateral lumbar)

65
Q

what should you do when xraying an elderly female?

A

decrease mas by 30-50%

66
Q

xrays that exit the patient and hit the film are called what?

A

remnant rays

67
Q

which grid is recommended for use in chiropractic offices?

A

focused grid

68
Q

which radiographic projections should use compensating filtration?

A

ap thoracic, lateral thoracic, and full spine

69
Q

comparing two films with constant kv and mas one taken at 40” and one at 72” what would occur?

A

increased density of the 40” and decreased image size of the 72”

70
Q

what is the 10 day rule?

A

10 days after the onset of menses is the safest time for xraying a female

71
Q

an accurate collimator should not allow more than ____% of the SID of light outside of the exposure field?

A

2%

72
Q

what is most effective at reducing secondary radiation?

A

filtration

Rad Physics (2 decks)

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