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Radiology Technician > brake test 3 > Flashcards

brake test 3 Flashcards

1
Q

As part thickness increase both film density and contrast decrease (true false)

A

true

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2
Q

What are the guidelines for selecting technical factors on an average patient tor a lateral abdomen or lumbar spine radiograph?

A
  1. Double mAs used for AP abdomen or AP lumbar spine radiograph
  2. increase by kV 15% for AP abdomen or lumbar spine radiograph
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3
Q

negative contrast agents attenuate less than soft tissue because of lower atomic # (true-false)

A

False ( because of density)

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4
Q

Positive contrast agents attenuate more than soft tissue and appear as areas of increased density on an image (true-false)

A

False ( increase brightness)

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5
Q

An infant chest will have less contrast than an adult chest (true-false)

A

True

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6
Q

To adapt exposure factors for a ten year old skull, it is recommended to use 15% less kVp used for adult patients (true-false)

A

False ( for infant 6 and under)

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7
Q

increasing added filtration to the tube will increase the HVL (true/false)

A

True

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8
Q

what is the effect of part thickness on radiographic density?

A

Makes >lighter, < film density and IR exposure

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9
Q

what is the effect of part thickness on radiographic contrast?

A

Contrast <, More noise

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10
Q

How is mAs adjusted to compensate for changes in part thickness

A

for every 4-5 cm in part thickness double mAs

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11
Q

How does a technologist measure part thickness?

A

caliper

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12
Q

compare the attenuation properties of positive contrast media with negative contrast agents.

A

Positive (Barium)- attenuate > than soft tissue & areas have > Z# = > brightness
Negative (Air)- attenuate < than soft tissue because < physical density = dark

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13
Q

if the normal technical factors for a lateral c-spine are 18 mAs and 79 kVp, what technical factors would be used for a soft tissue lateral neck taken with a film IR?
What needs to be done with a digital IR

A

decrease kVp by 15% = 67kVp and 18mAs

nothing the algorithms or AEC will change it

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14
Q

The normal technical factors for a AP angle are 10 mAs and 60 kVp. Based on the theory that wet casts attenuate differently than dry cast, what technical factors would be used if the ankle is in a full wet plaster cast?
What technical factors would be used if the ankle is in a full dry case?

A

wet cast = increase the kVp by 22% = 73kVp and 10mAs or increase mAs by 3X = 60kvp and 30mAs
dry cast = increase the mAs by 2X = 60kVp and 20 mAs or increase the kVp by 15% = 70kVp and 10 mAs

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15
Q

The normal technical factors for a chest x-ray taken on inspiration are 115kVp and 6mAs. What technical factors should be used for a chest x-ray taken on expiration?

A

increase mAs by 30% = 115kVp and 8mAs

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16
Q

a frail, elderly patient comes to the radiology department for a lumbar spine series. The history on the requisition states the patient has osteoporosis. The patient is average size but as the patient gets on the x-ray table, he complains of how hard the table is for him because he is just “skin and bone” with no body fat for cushioning. When you set your technical factors for the AP radiograph, you read the technique chart on the wall which state the average technique for an AP lumbar is 80kVp and 30mAs. What technical factors will you use?
Why?

A

reduce kVp by 15%

Because the elderly patient has less bone calcium, less fluid and osteoporosis is a destructive diseases of the bone.

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17
Q

An impatient is sent to radiology for an obstructive series. The history on the requisition state the patient has ascites. The patient seems of average size but you notice when palpating for bony landmarks that the abdomen is tightly distended and very firm. You read the technique chart on the wall which states the average technique for a KUB is 80kVp and 30mAs. What technical factors will you use for this patient’s KUB?

A

increase mAs 25-50%
Because the patient is doing a KUB that’s basically air we would use mAs changes and the patient has ascites an additive disease

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18
Q

an impatient is sent to radiology for an obstructive series. The history on the requisition state the patient has a bowel obstruction. The patient is average size but you notice when palpating for the iliac crest that the abdomen is tightly distended and very firm. You read the technique chart on the wall which state the average technique for a KUB is 80kVp and 30mAs. What technical factors will you use for this patient’s kUB

A

decrease the mAs by 25-50%

because it a destructive air disease

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19
Q

with an average torso thickness of 22cm, technical factors for a portable chest are 75kVpp and 3mAs. What factors should be used if torso thickness is 26cm.

A

increase mAs by 2X= 75kVp and 6mAs

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20
Q

the average adult torso thickness in the AP projection is 22cm. What is the average thickness for the lateral projection?

A

8cm thicker

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21
Q

Technical factors for an AP lumbar spine are 85kVp and 32mAs. How should the technical factors be adjusted form the lateral lumbar spine?

A

increase mAs by 2X - 85kvp and 64mAs and increase kVp by 15% (10 rule) = 95kVp and 32mAs

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22
Q

summarize the technical factor adjustments recommended for pediatric patients

A

lower (kVp and mAs) and shorter exposure time to eliminate motion

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23
Q

List the order of greatest attenuation to lowest the following tissues: soft tissue, bone, lung, fat, muscle

A

bone, muscle, soft tissue, fat, lung

24
Q

compare the radiographic appearance (density) of positive contrast media with negative contrast agents.

A

positive contrast media (density) is bright

negative contrast agent ( density) is dark

25
Q

Provide examples of positive and negative contrast agents?

A

Positive agent = barium and iodine

negative agent = air and gas

26
Q

compare the recommended kVp ranges for GI procedures using barium only, barium with air and aqueous agents

A

barium 100-125kvp
double contrast 90-100kvp
aqueous 80-90kVp
GI procedures 70-75 (analog) 75-80 (digital)

27
Q

Explain the effect of filtration on beam intensity and beam quality

A

beam intensity - decrease

beam quality - increase

28
Q

Define HVL. What does HVL measure

A

HVL determines the filtration to the tube is correct and beam should only decrease 1/2 of the value
HVL measures the beam intensity after filtration has been added

29
Q

What is the difference between tube filtration and compensating filtration? Compare the purpose of each

A

tube filtration is what is in or on the tube to reduce low energy photons hitting the patient.
compensating filtration is what is used to compensate for anatomical parts being photograph with different attenuation factors.(wedge and trough)

30
Q

What are the 2 purposes of collimation

A
  1. reduce patient exposure

2. reducing the amount of scatter radiation produced within the patient

31
Q

List 4 types of collimation devices

A

cones, cylinder, apertures and collimator boxes

32
Q

what is the relationship on increased collimation on field size and volume of tissue exposed?

A

increased collimation = small field size and less tissue being exposed on the patient

33
Q

what is the effect of increased collimation on the following image qualities?

A

scatter noise=decrease
contrast=increase
film density=decrease
detail sharpness=no effect

34
Q

explain mAs reciprocity

A

verifies the insistency of radiation intensity for changes in ma and exposure time

35
Q

What does linearity state about the relationship between radiation exposure and mA, s, and mAs?

A

that mA time S = mAs

36
Q

what is the name of the device that is used to measure x-ray intensity?

A

dosimeter or film badge

37
Q

what is the unit of measurement for x-ray intensity?

A

roentgen

38
Q

collimator misalignment should be ____ ______ ___ of the SID used

A

less than 2\

39
Q

how much ( in inches) can the collimator be misaligned if using 40” SID

A

0.8”

40
Q

PBL does not allow technologist to collimate to a field size that is larger that the IR (true/false)

A

true

41
Q

PBL was once required by federal law but currently is not (true/false)

A

true

42
Q

Excessively bright or dark digital images are produced by rescaling errors (true/false)

A

true

43
Q

if there is rescaling errors, the exposure index is not accurate (true/false)

A

true

44
Q

if collimation guidelines are not followed an excessively bright or dark image may be produced when using a digital IR (true/false)

A

true

45
Q

explain the difference between off-focal radiation and scatter radiation

A

off focus radiation come from electrons that strike somewhere other then anode, and scatter radiation come form the patients anatomical parts

46
Q

why is it desirable to reduce off-focal radiation and how can it be reduced?

A

it contributes to patient dose

it can be reduced by double aperture device, extension cylinder or collimator box.

47
Q

Summarize the guidelines for collimation and split exposures when using a CR image receptor. Why is important to follow these guidelines?

A 
2 exposure fields should be used except for digits
shield all areas not being exposed
symmetry is important
no overlap between field
collimation margins between fields
48
Q

To utilize the anode heel effect, the cathode end of the tube should be positioned over the thickest body part of interest (true/false)

A

true

49
Q

the total required filtration reduces patient skin dose without any effect on radiographic images (true/false)

A

true

50
Q

high kv should be used with body parts that have high subject contrast (true/false)

A

true

51
Q

increasing added filtration to the tube will decrease the HVL (true/false)

A

false

52
Q

as collimation in increased (select all that apply)

A

size field decrease
contrast increase
film density decrease
scatter radiation decrease

53
Q

what are the effects of scatter radiation on image quality

A

film density increase
contrast decrease
scatter noise increase

54
Q

a sthenic patient will attenuate more of the x-ray beam than a hyper sthenic patient of the same size and thickness (true/false)

A

true

55
Q

when using a wedge filter for a AP foot the thinnest end of the filter should be paced over the toes (true/false)

A

false

56
Q

which of the following conditions will make the anode heel effect more notice

A

longer IR
small focal spot
shorter SOD

57
Q

positive contrast agents increase attenuation because of the high physical density (true/false)

A

false (atomic #)

Radiology Technician (6 decks)

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