18 Questions
Why were Phototimer AEC devices considered exit-type devices?
Due to the positioning of detectors behind the IR
What is the function of a phototimer in radiography?
Measure the radiation received by the detectors
What type of devices largely replaced phototimers in radiography?
Ionization chamber systems
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
What happens when a sufficiently large charge is received by the light paddles in a phototimer?
The timer is tripped and exposure is terminated
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
What is the purpose of exposure technique charts in radiography?
To standardize the selection of exposure factors
In radiography, what happens when the mAs is not adjusted accordingly for changes in part thickness?
Long exposure time
How does the variable kVp/fixed mAs technique chart adjust for different anatomic part sizes?
Raising kVp as part size increases
What is the consequence of insufficient collimation during a radiographic exposure?
Longer exposure time
When using a fixed kVp/variable mAs technique chart, what is adjusted for variations in part thickness?
mAs values
Why is quality control important in monitoring the performance of an AEC system?
To ensure reproducibility of exposures
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.
How does adjusting the kVp setting affect exposure time in an AEC system?
Increasing or decreasing the kVp directly impacts exposure time.
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.
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.
What does the backup time (mAs) feature provide in an AEC system?
A safety mechanism to prevent exposure from exceeding a set limit.
What is a common limitation associated with AEC systems in radiography?
Allowing only one type of IR.
Learn about phototimers, photomultiplier tubes, photodiodes, and how they convert light energy into electrical energy. Explore the use of AEC devices in radiology and the different types of light-detecting technologies.
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