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Rad Tech School 2024 - 2026 > Imaging Ch8 > Flashcards

Imaging Ch8 Flashcards

1
Q

What is an AEC?

A

AEC stands for Automatic Exposure Control
It used to consistently control the amount of radiation reaching the image receptor by terminating the length of exposure

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2
Q

Where is an AEC found?

A

In the bucky or the chest rack

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3
Q

AECs are also known as:

A

Automatic exposure device or phototiming

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4
Q

AECs determine:

A

exposure time and how much exposure is used

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5
Q

T/F: When using an AEC, selecting appropiate factors are not needed?

A

False
-factors are still important in order to not overexpose the patient

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6
Q

How many types of AECs are there?

A

2

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7
Q

What are the main types of Automatic Exposure Controls?

A

Phototimers and Ionization chambers

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8
Q

What type of AEC uses light or flourenscence?

A

Phototimer

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9
Q

What does a photomultiplier do?

A

It is used to convert visible light into electrical energy

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10
Q

What is the difference between a photomultiplier and a photodiode ?

A

there is no difference

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11
Q

Are phototimers behind or in front of the IR?

A

behind

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12
Q

Does a Photoitmer decrease patient dose?

A

No

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13
Q

What is the most common type of AEC used today?

A

Ionization Chamber

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14
Q

A hollow cell that contains air and is connected to a timer curcuit by electrical wire is what type of AEC?

A

ionization chamber

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15
Q

What type of detector is positioned in front of the IR?

A

Entrance-type devices

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16
Q

What is a mAs readout?

A

is shown on an AEC immediately after exposure. It shows the actual amount of mAs that was used

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17
Q

The shortest exposure time that a system can produce

A

minimum exposure time

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18
Q

What is the maximum length of time the x-ray exposure will continue when using an AEC?

A

backup time

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19
Q

The kilovoltage selection :

A

determines the length of exposure time when using an AEC

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20
Q

When using an AEC, a low kVp requires _____ exposure time

A

More

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21
Q

When using an AEC, a ____ kVp requires more exposure time

A

Low

22
Q

When using an AEC, a _____ kVp needs a decrease in exposure time.

A

High

23
Q

When using an AEC, a high kVp needs a ____ in exposure time.

A

Decrease

24
Q

T/F: The thinnest part goes on the photocells.

A

False
-the thickest part should be superimposed on photocells to prevent burnout

25
Q

When increasing patient thickness, exposure time is ____

A

Increased

26
Q

when increasing mA, exposure time _____

A

Decreases

27
Q

When decreasing kVp, exposure time must _____

A

Increase

28
Q

When decreasing SID, exposure time must _____

A

Decrease

29
Q

When increasing OID, exposure time must _____

A

Increase

30
Q

When the anatomic part has excessive gas, the exposure time must _____

A

Decrease

31
Q

Different types of IRs have no effect on exposure time but may affect ______

A

image quality

32
Q

When there is excessive collimation, exposure time must be _____

A

increased

33
Q

When there is increased exposure adjustment, exposure time must be __________

A

increased

34
Q

What type of patients are exposure technique charts designed for ?

A

sthenic or average

35
Q

How many types of exposure technique charts are there? What are they?

A

2
Variable kVp-fixed mAs
Fixed kVp-variable mAs

36
Q

What is the device used to measure part thickness?

A

Calipers

37
Q

What is the rule when using a variable kVp-fixed mAs :

A

the kVp is increased by 2 for every 1cm increase in part thickness (+2)

38
Q

What are the advantages of using a variable kVp- fixed mAs technique ?

A

they are easy to construct and are simple to use
at low kvp levels, small changes in kVp are more effective

39
Q

What are the disadvantages of using a variable kVp-fixed mAs technique?

A

Anatomic part penetration isn’t guaranteed
Changing kVp is less effective for a range of procedures
Less accurate for part size extremes (may not penetrate)

40
Q

What is a fixed kVp- variable mAs used for?

A

to penetrate the part without diminishing subject contrast

41
Q

What is the rule for a fixed kVp-variable mAs technique?

A

for every 4-5 cm change in part thickness, mAs should be adjusted by a factor of 2 (x2)

42
Q

What patients would require special considerations?

A

pediatric, geriatric, and bariatric

43
Q

A pediatric(child) patient would require:

A

a reduction in exposure
quicker exposure times

44
Q

A geriatric(elder) patient would require:

A

a decrease in exposure techniques
lower kVp and increased mAs to decrease exposure time

45
Q

A bariatric(bigger) patient would require

A

an increase in kVp and mAs
a grid
they may need to be imaged in quadrants

46
Q

T/F: certain projections and positions may require changes in exposure technique due to changes in tissue thickness.

A

true

47
Q

T/F: plaster casts require a decrease in exposure factors.

A

False
- plaster casts require an INCREASE in exposure factors

48
Q

T/F: Splints may require adjustments in exposure factors due to the type of material if in the path of the beam.

A

true

49
Q

T/F: mAs may need to be decreased to visualize soft tissues.

A

true

50
Q

T/F: Digital allows for visualization of soft tissue without changing exposure techniques.

A

true

51
Q

T/F: contrast media is used to increase radiographic contrast when imaging areas of high subject contrast.

A

False
- contrast media is used to increase contrast when imaging areas of LOW subject contrast

Rad Tech School 2024 - 2026 (9 decks)

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