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RSC1101Ch13
Exposure Technique Selection
| Question | Answer |
|---|---|
| A system used to control radiation reaching the IR by terminating length of exposure. | AEC |
| More common AEC system | Ionization chambers |
| Which device uses a fluorescent screen and converts light to electricity? | Phototimer |
| If the image is unacceptable, knowing the mAs readout provides a basis from which the radiographer can make exposure adjustments by switching to a ___. | Manual Technique |
| An electronic device that converts visible light energy into electrical energy | Photomultiplier tube (PMT) |
| The RT must select the ____ level to provide the appropriate scale of contrast | kVp |
| Using higher kVp with AEC ___ the exposure time and overall mAs needed. | decreases |
| Using lower mA ___ the exposure time | increases |
| System that allows the RT to adjust the amount of preset radiation detection values, generally in the form of buttons on the control panel numbered -2, -1, +1, +2 | Exposure Adjustment or Density Controls |
| If the XR field size is collimated too closely, the detector does not receive sufficient exposure and may prolong the exposure time, resulting in ___. | Overexposure |
| Improper centering the T spine could result in ___ of the T spine and ___ of the lung field. | Underexposure, overexposure |
| AEC systems compensate for changes in patients ___. | Thickness |
| Failure to collimate sufficiently can cause the detector to prematurely terminate the exposure. (T/F) | True |
| What AEC device uses PMTs or photodiodes to convert visible light energy into electrical energy? | Phototimer |
| 4 terms for radiation measuring devices: | detectors, chambers, cells, sensors |
| A hollow cell that contains air and is connected to the timer circuit via an electrical wire | ionization chamber |
| A low kVp requires ___ exposure time. | more |
| Backup time should be set to ___-___ of the expected exposure time. | 150-200% |
| Bariatric pt exams may require ___ to reduce scatter | Grids |
| Pediatric pt exams may require increasing the ___ to decrease the exposure time | mA |
| T/F: fiberglass casts require an increase in exposure factors by 10%. | False- no change required for DR |
| Additive diseases ___ the absorption of the XRB, requiring and increase in ___. | increase, kVp |
| A pt with free air in the body would need what change in exposure factors? | decrease kVp |
| What substances can be used when imaging anatomic tissues with low subject contrast? | contrast medium |
| What is a negative contrast agent? | Air |
| T/F: Exit type devices use ionization chambers to create an electrical charge when receiving the radiation. | False- entrance type devices |
| What is the minimum response time for modern AEC systems? | 1 ms |
| Exposure adjustments are generally in the form of buttons numbered -2, -1, +1, and +2, which are generally in increments of ___. | 25% |
| Failure to use proper detectors could result in ___ or ___ to the IR. | underexposure, overexposure |
| If the XR field size is collimated too much, the exposure time could ___, resulting in what type of exposure? (over/under) | increase, overexposure |
| Which type of exposure technique charts are most appropriate for pediatric extremities? | fixed kVp variable mAs |
| (T/F): fixed mAs variable kVp charts are most accurate for extreme differences in part size. | False- fixed kVp variable mAs |
| For peds under 6 years of age, the RT should decrease kVp by at least ___%. | 15% |
Created by:
lipscombsomi