Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
AEC
| Question | Answer |
|---|---|
| AEC is controlled at the | console |
| AEC automatically terminates the exposure when it detects | enough radiation to produce an optimal image |
| While AEC controls ___, the Technologist still selects ____. | Time; kv, IR, ma, grid |
| A phototimer AEC is located | behind the IR |
| Phototimers work by | 1. light passes through the pt, travel through the IR and hit a fluorescent screen. It emits light proportional to receptor exposure. phototimer measures the light ans shuts off when enough is detected. |
| phototimers are risky because they | 1. increase pt dose due to placement 2. can be inaccurate if there is any issue with the IR 3. slower response time |
| which AEC is a direct method | ionization chambers |
| ionization chambers are located | between the pt and the IR in the bucky |
| In ionization chamber AEC, xrays pass through the pt and into the gas chambers. How does this terminate exposure? | the xrays ionize the gas, this creates an electric charge that travels along a wire to the timer circuit. The timer is tripped when sufficient charge is detected. |
| Downsides to ionization AEC | requires very precie positioning of the part over selected chambers. can create errors if wrong cell selected. not ideal for small anatomy, peds, or mobile exams. |
| ionization AEC is ____ than phototimers | faster and more accurate |
| in AEC, mAs is | output not input |
| why should you look at the mAs readout | to make technique or positioning adjustments, and to learn manual techniques |
| minimum response time | the shortest time the system can produce to detect radiation and end exposure |
| maximum length of time the exposure could last what % of expected exposure time is it | back up time 150% |
| whats the safety mechanism for exposure time | back up time- prevents excessive pt exposure |
| advantages of AEC | reduces dose, reduces repeats, consistent image, adapts to pt differences |
| most AEC have _ cell detectors | 3 |
| For AEC, exposure is determined by | part thickness |
| after an exposure is made the ions recombine and become | neutral |
| AEC should make the ___ similar for each image | brightness |
| AEC has no affect on ___ | contrast |
| AEC measures the amount of ___ radiation | remnant |
| the ___ can be used to adjust the sensitivity of the detector if you want to manually increase/decrease exposure | exposure control selector |
| if the pt is thick and the part is dense | there will be less radiation reaching the detector and a longer exposure time |
| tightly collimated exams could be | overexposed |
| non collimated exams could be | underexposed |
| speed class | how sensitive the IR is to xrays |
| a lower speed class system requires a high speed class system requires | more radiation less radiation |
| is it better to have a fixed kVp and adjustable mAs because | allows adjustments for pt thickness |
| For every 4cm of increased pt thickness, | mAs should be increased by 2 |
Created by:
user-1989152