Phototimers and Light-Detecting Devices

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Why were Phototimer AEC devices considered exit-type devices?

Due to the positioning of detectors behind the IR (correct)

Because they were replaced with ionization chamber systems

They produced visible light upon radiation interaction

Because they converted radiation into electricity

What is the function of a phototimer in radiography?

Convert visible light energy into electrical energy

Measure the radiation received by the detectors (correct)

Produce visible light upon radiation interaction

Convert radiation into electricity

What type of devices largely replaced phototimers in radiography?

Photomultiplier tubes

Fluorescent screens

Ionization chamber systems (correct)

Photodiodes

How is the total amount of radiation determined in a radiographic study using an AEC device?

By displaying the actual mAs used on a display Signup and view all the answers

What happens when a sufficiently large charge is received by the light paddles in a phototimer?

The timer is tripped and exposure is terminated Signup and view all the answers

Why is it critical for a radiographer to note the mAs readout display after an exposure?

To verify the amount of radiation used for that image Signup and view all the answers

What is the purpose of exposure technique charts in radiography?

To standardize the selection of exposure factors Signup and view all the answers

In radiography, what happens when the mAs is not adjusted accordingly for changes in part thickness?

Long exposure time Signup and view all the answers

How does the variable kVp/fixed mAs technique chart adjust for different anatomic part sizes?

Raising kVp as part size increases Signup and view all the answers

What is the consequence of insufficient collimation during a radiographic exposure?

Longer exposure time Signup and view all the answers

When using a fixed kVp/variable mAs technique chart, what is adjusted for variations in part thickness?

mAs values Signup and view all the answers

Why is quality control important in monitoring the performance of an AEC system?

To ensure reproducibility of exposures Signup and view all the answers

What is the purpose of detectors in an AEC system?

To measure the amount of radiation exiting the patient and stop the exposure at a preset level. Signup and view all the answers

How does adjusting the kVp setting affect exposure time in an AEC system?

Increasing or decreasing the kVp directly impacts exposure time. Signup and view all the answers

What is the role of mA adjustments in relation to exposure time in AEC systems?

Changing mA settings leads to proportional changes in exposure time. Signup and view all the answers

Why is it crucial for the x-ray beam to be precisely centered to the anatomic area of interest for AEC to function accurately?

To ensure proper detector coverage and radiation measurement. Signup and view all the answers

What does the backup time (mAs) feature provide in an AEC system?

A safety mechanism to prevent exposure from exceeding a set limit. Signup and view all the answers

What is a common limitation associated with AEC systems in radiography?

Allowing only one type of IR. Signup and view all the answers