Term
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Definition
| eliminate need for radiographer to set exposure time |
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Term
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Definition
beam passes through patient, tabletop, IR, and THEN photodetector
calibrated by setting capacitor discharge at point that producies satifactory density |
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Term
| components of a phototimer |
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Definition
fluorescent screen
photomultiplier tube
capacitor
thyratron |
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Term
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Definition
| absorbs xrays and produces light photons |
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Term
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Definition
| produces electrons form the light photons received from fluorescent screen |
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Term
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Definition
| discharges when reaches present value, triggering thyratron and opening relay to terminate exposure |
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Term
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Definition
| regulates exposure automatically |
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Term
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Definition
| beam passes through patient and table top before striking the ionization chamber |
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Term
| components of ionization chamber |
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Definition
flat, parallel plate ionization chamber
made radiolucent |
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Term
| ionization within the chamber creates a |
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Definition
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Term
| exposure is terminated when |
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Definition
| appropriate charge has been reached |
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Term
| most creitical element in using AECs |
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Definition
| exact position of ion chambers must be known to radiographer |
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Term
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Definition
time the electronic timer is set in case AEC fails to terminate exposure
cannot exceed tube limit and should be set 150% of anticipated mAs |
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Term
| regulations require that AEC has ___ mAs and ___ mAs safety override |
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Definition
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