AEC continued

Question 1

What do exposure adjustments/density selectors do?

Answer 1

-They either extend or shoten the exposure time using AEC
-Once you reach the pre-determined amount of radiation, it will allow the exposure to continue or stop early based on the value that you have slected (+,-)

Question 2

If you select a - denisty selector, what technique will it shorten?

Answer 2

Shortens mA-Will give you a shorter mAs

Question 3

How much do density selectors increase or shorten exposure?

Answer 3

-Increases the time ussually by 30-50%, but can be callibrated differently

Question 4

When do we use exposure adjustments/density selectors?

Answer 4

1. Use them for high scatter situations
2. Use them for really thin patients

Question 5

Why would we use a density selector for thin patients? What type of density selector would we choose?

Answer 5

Use them for really thin patients since we are getting less scatter than the system is calibrated to see

Would use a + density selector

Question 6

What is fixed mode?

Answer 6

• What you see is what you get
• System will not recalibrate
• Very big differences between images

Question 7

What is auto mode?

Answer 7

• System will fix things for us
• Cannot tell the difference with different exposure adjustments
• mAs and EI value will change

Question 8

When will AEC be an issue?

Answer 8

1. If the anatomy doesnt fully cover the cell
2. Not imaging in the bucky
3. Bad positioning or centering
4. Radiopauqe objects

Question 9

Should we use AEC for an odontoid position, why or why not?

Answer 9

No, due to the absorption of radiation from the teeth

Question 10

When doing a lateral lumbar spine with AEC, what considerations should you make?

Answer 10

The light may be on the table, so we should out lead sheilding on the side to absorb the scatter

Question 11

If the light is not fully covering the detector, what happens to mAs?

Answer 11

The detector sees less radiation per unit time, so it lengthens the exposure giving us a higher mAs

Question 12

In which situations would the anatomy not be fully covering the detector?

Answer 12

1. Lateral facial bones
2. Scapula
3. Clavicle
4. Lateral hip

Question 13

What detectors should you use when imaging an abdomen?

Answer 13

All three AEC detectors to average out over the entire abdomen

Question 14

What will absorb more radiation, lung tissue or heart tissue?

Answer 14

Heart tissue-more density

Question 15

When doing a PA chest, what detectors should we use?

Why?

Answer 15

We want the detectors on the L and R side of the lung above the diaphram, because with deep inspiration, the diaphram is pushed down, and the heart is moved away from the detector.

Question 16

What detector(s) should we use with a lateral chest?

Answer 16

Only center detector

Question 17

Which abnormal situations should you NOT use AEC?

Answer 17

1. Pneumothorax
2. Lung markings/single masectomy
3. Suspected cardiomegly
4. Barium enema

Question 18

What are some of the causes of AEC overexposure?

Answer 18

1. Wrong bucky activated
2. Needed time is less than MRT
3. Density left on + setting
4. Incorrect detector cell selection
5. Radiopaque artifacts
6. Electronic malfunction

Question 19

What are the causes of AEC underexposure?

Answer 19

1. Back-up time is less than needed exposure time and terminates early
2. Density left on the - setting
3. Inadequate collimation-feild size too large for body part we are doing
4. Inadequate detector cell selection

Question 20

What happens when using a falling load generator with AEC?

Answer 20

The mA drops severat times during the exposure based on the maximum heat loading capacity of the tube

Question 21

What percentage of falling load should we use with AEC?

Answer 21

100%

Question 22

What is the function of a falling load generator?

Answer 22

Starts the exposure with the highest mA for the selected kVp