Imaging Ch8

Question 1

What is an AEC?

Answer 1

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

Question 2

Where is an AEC found?

Answer 2

In the bucky or the chest rack

Question 3

AECs are also known as:

Answer 3

Automatic exposure device or phototiming

Question 4

AECs determine:

Answer 4

exposure time and how much exposure is used

Question 5

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

Answer 5

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

Question 6

How many types of AECs are there?

Answer 6

2

Question 7

What are the main types of Automatic Exposure Controls?

Answer 7

Phototimers and Ionization chambers

Question 8

What type of AEC uses light or flourenscence?

Answer 8

Phototimer

Question 9

What does a photomultiplier do?

Answer 9

It is used to convert visible light into electrical energy

Question 10

What is the difference between a photomultiplier and a photodiode ?

Answer 10

there is no difference

Question 11

Are phototimers behind or in front of the IR?

Answer 11

behind

Question 12

Does a Photoitmer decrease patient dose?

Answer 12

No

Question 13

What is the most common type of AEC used today?

Answer 13

Ionization Chamber

Question 14

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

Answer 14

ionization chamber

Question 15

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

Answer 15

Entrance-type devices

Question 16

What is a mAs readout?

Answer 16

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

Question 17

The shortest exposure time that a system can produce

Answer 17

minimum exposure time

Question 18

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

Answer 18

backup time

Question 19

The kilovoltage selection :

Answer 19

determines the length of exposure time when using an AEC

Question 20

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

Answer 20

More

Question 21

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

Answer 21

Low

Question 22

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

Answer 22

High

Question 23

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

Answer 23

Decrease

Question 24

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

Answer 24

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

Question 25

When increasing patient thickness, exposure time is ____

Answer 25

Increased

Question 26

when increasing mA, exposure time _____

Answer 26

Decreases

Question 27

When decreasing kVp, exposure time must _____

Answer 27

Increase

Question 28

When decreasing SID, exposure time must _____

Answer 28

Decrease

Question 29

When increasing OID, exposure time must _____

Answer 29

Increase

Question 30

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

Answer 30

Decrease

Question 31

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

Answer 31

image quality

Question 32

When there is excessive collimation, exposure time must be _____

Answer 32

increased

Question 33

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

Answer 33

increased

Question 34

What type of patients are exposure technique charts designed for ?

Answer 34

sthenic or average

Question 35

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

Answer 35

2 Variable kVp-fixed mAs Fixed kVp-variable mAs

Question 36

What is the device used to measure part thickness?

Answer 36

Calipers

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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)

Question 40

What is a fixed kVp- variable mAs used for?

Answer 40

to penetrate the part without diminishing subject contrast

Question 41

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

Answer 41

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

Question 42

What patients would require special considerations?

Answer 42

pediatric, geriatric, and bariatric

Question 43

A pediatric(child) patient would require:

Answer 43

a reduction in exposure quicker exposure times

Question 44

A geriatric(elder) patient would require:

Answer 44

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

Question 45

A bariatric(bigger) patient would require

Answer 45

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

Question 46

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

Answer 46

true

Question 47

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

Answer 47

False - plaster casts require an INCREASE in exposure factors

Question 48

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

Answer 48

true

Question 49

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

Answer 49

true

Question 50

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

Answer 50

true

Question 51

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

Answer 51

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