Chapter 7

Question 1

When were AECs introduced?

Answer 1

1942

Question 2

Who introduced AECs?

Answer 2

Russell H. Morgan

Question 3

What is the most critical element in using AEC?

Answer 3

The exact position of the ionization chambers

Question 4

Automatic exposure devices provide

Answer 4

Diagnostic-quality exposures only for structures positioned directly above the ionization chambers

Question 5

What is the most common relationship (configuration) of the three chambers?

Answer 5

The center chamber at the center of the image receptor with right and left chambers slightly higher.

Question 6

Where does the most common three chamber relationship place the center chamber?

Answer 6

Below the duodenum and transverse colon for most abdominal examinations

Question 7

Where does the most common three chamber relationship place right and left chambers?

Answer 7

Away from the mediastinum and completely within the lives of the lungs during chest x-rays.

Question 8

How many different combinations of using the three chambers is there?

Answer 8

Seven

Question 9

What is averaging?

Answer 9

The signals from the cells are sent through i a special operating lap amplifier, which sums the voltages received from each cell and divides by the number of cells that have been activated

Question 10

Call selection is determined by….

Answer 10

The radiographer based on knowledge of anatomy and positioning

Question 11

Automatic exposure controls require the use of _______________________ that specify the technical parameters to be used.

Answer 11

Exposure technique charts

Question 12

If there is fluid in the lungs, does it cause increased or decreased subject density and contrast?

Answer 12

Increased, the AEC would remain on longer, making an aerated lung overexposed for diagnosis

Question 13

What is the minimum response time?

Answer 13

The length is time necessary for the AEC to respond to the ionization and send a signal to terminate the exposure.

Question 14

Modern AEC’s have a minimum response time in the region of ____ seconds.

Answer 14

0.001

Question 15

What does the back up time establish?

Answer 15

The maximum exposure time for the system in order to prevent overexposure.

Question 16

U.S. public law requires that generators automatically terminate AEC exposures at ____ mAs or ___ kilowatt seconds (kWs) above 50 kVp, and 2,000 mAs below 50 kVp.

Answer 16

600; 60

Question 17

What will happen if the back up time is too short?

Answer 17

It will terminate the exposure before the AEC signal, thus producing an underexposed image.

Question 18

What does the anatomically programmed radiography (APR) units combine?

Answer 18

An ARC system with be exposure system that is computerized to correspond to anatomical procedures.