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6 Cards in this Set
- Front
- Back
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What is the device that enables phototiming and how does it work?
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Thyratron
Located behind cassette Fluorescent screen emits light photons Light photons strike photomultiplier tube PM tube releases electrons to capacitor Capacitor accumulates need charge Exposure is terminated |
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What is the device that enables AEC and how does it work?
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Ionization chamber
Located in front of cassette 5mm parallel plate chamber |
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What is a Silicon-controlled rectifier (SCR)
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Found in AEC units
A complex semiconductor used for switching of the primary high voltage x-ray circuit Also known as a thyristor |
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What is minimum reaction time?
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Minimum amount of time required to terminate exposure in AEC
Modern minimum reaction time 0.001 seconds |
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What is backup time?
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Equipment often allows technologist to set a backup
Should be set at 150% of anticipated manual technique Maximum exposure per U.S. Public Law 600 mAs |
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What is vitally important when using AEC and why are repeats more difficult than when using manual technique?
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Positioning is crutial since the ionization chambers have to be located at anatomy of interest.
It is easy to adjust manual technique up or down on a repeat but AEC can leave the technologist guessing as to why the image needs repeating |
