Help
Options
Question
AEC devices work by measuring:
click to flip
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't know
Question
What exposure system operates by ionizing air that creates an electrical charge?
Remaining cards (78)
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
RSC1101FINAL2
Chapter 11 and 13 kahoot
| Question | Answer |
|---|---|
| AEC devices work by measuring: | exit radiation |
| What exposure system operates by ionizing air that creates an electrical charge? | ionization chamber |
| During the operation of the AEC device, the time of exposure is ____(directly, inversely) related to the intensity of exit radiation. | directly |
| What are 3 important factors to consider when using AEC devices? | 1. detector selection 2. centering part to detector 3. backup mAs |
| Increasing the pt thickness while using an AEC device would result in: | increased exposure time |
| Primary goal of exposure technique charts? | consistency in image quality |
| What exposure technique system uses a fixed mAs regardless of pt thickness? | variable kVp |
| What is the most important when using a technique chart? | accurately measure pt |
| An advantage of the variable kVp technique chart is that it | makes smaller technique changes possible |
| Which 2 considerations may require a decrease in mAs? | soft tissue exam and pediatric pt |
| Which 3 considerations may require an increase in mAs? | 1. contrast medium 2. bariatric pt 3. tissue edema |
| Which AEC device uses light paddles, coated with a fluorescent material to convert light to electricity? | phototimers |
| (T/F): A PMT is the only device used by a phototimer to convert light energy into electricity. | False- also uses photodiode |
| A hollow cell that contains air and is connected to the timer circuit via an electrical wire. | ionization chamber |
| Detectors positioned behind the IR so that radiation must exit the IR before it is measured by the detectors. | exit type device |
| (T/F): Ionization chambers are exit-type devices. | False- phototimers are exit-type |
| 3 other terms for AEC detectors? | 1. sensors 2. chambers 3. cells |
| Displays actual amount of mAs used for the image: | mAs readout |
| (T/F): AEC controls only the quantity of radiation reaching the IR and therefore has no effect on contrast. | True |
| A low kVp requires ___ exposure time to reach the predetermined amount of exposure. | more |
| Increasing mA ___ exposure time to reach the predetermined amount of exposure. | decreases |
| (T/F): The minimum response time with most modern AEC systems is 1 ms. | True |
| The maximum length of time the XR exposure continues when using an AEC system: | backup time |
| (T/F): The backup time should be set at 150-200% of the expected exposure time. | True |
| Tool that allows the RT to adjust the amount of preset radiation detection values: | exposure adjustment |
| (T/F): The density control numbers change exposure time by some predetermined amount or increment expressed as a percentage. | True |
| (T/F): The size of the detectors within an AEC system can be adjusted by the RT. | False |
| (T/F): Accurate centering of the AOI over the detectors is critical to ensure proper exposure to the IR. | True |
| If the AOI is thicker due to pt size, the exposure time will ___ to reach the preset exposure. | lengthen |
| An XR field size that is collimated too closely will ___ exposure time, resulting in ___. | increase; overexposure |
| (T/F): Different types of IRs can be interchanged easily once an AEC device is calibrated. | False |
| A pre-programmed set of exposure factors displayed and selected for use on the control panel: | anatomically programmed technique |
| Manual exposure techniques should be used for what 4 factors? | 1. pediatric pts 2. anatomic parts that do not adequately cover the detectors 3. pathology 4. contrast media |
| Reproducibility of exposures and selected detector should result in mR readings within ___. | 5% |
| Pixel brightness levels for areas within the displayed image should be within ___. | 30% |
| Pre-established guidelines used by the RT to select standardized manual or AEC exposure factors for each exam: | exposure technique charts |
| 3 variables on a technique chart? | 1. kVp 2. mAs 3. grid |
| Devices that measure part thickness: | calipers |
| Based on the concept that kVp can be increased as the anatomic part size increases: | variable kVp-fixed mAs |
| The baseline kVp is increased by ___ for every ___ cm increase in thickness when using variable kVp-fixed mAs charts. | 2; 1 cm |
| Concept of selecting an optimal kVp that is required for the exam and adjusting the mAs for variations in thickness: | fixed kVp-variable mAs |
| kVp that is high enough to ensure penetration of the part but not too high to diminish subject contrast: | optimal kVp |
| For fixed kVp-variable mAs charts, for every ___ cm change in part thickness, mAs should be adjusted by a factor of ___. | 4-5 cm; 2 |
| The concept that different parts of the same size can be radiographed by use of the same exposure factors: | comparative anatomy |
| Exposure techniques may need to be ___ for pts who appear thin and frail. | decreased |
| (T/F): Pediatric imaging requires long exposure times. | False |
| (T/F): Fiberglass casts require an increase in exposure factors, whereas plaster casts do not. | False |
| Conditions that increase the absorption characteristics of the part, making the part more difficult to penetrate: | additive diseases |
| When imaging pathologic conditions, which exposure factor is routinely adjusted? | kVp |
| Destructive diseases require a(n) ___ in kVp. | decrease |
| Positive contrast media appear ___ on a RG image and require a(n) ___ in exposure factors. | white; increase |
| A bowel obstruction is considered a(n) ___ disease. | destructive disease |
| A pleural effusion is considered a(n) ___ disease. | additive |
| What type of relationship does mAs have with the exposure reaching the IR? | direct |
| What describes the relationship between mA and exposure time to maintain exposure to the IR? | inverse |
| Increasing the mAs has ___ effect on brightness displayed in digital imaging. | no |
| given the anatomic part is adequately penetrated, changing the kVp will affect: | both Compton scattering and subject contrast |
| Which of the following factors do not affect spatial resolution? | grid |
| The amount of remnant radiation will decrease when increasing ___. | tissue thickness |
| What factor affects the amount of radiation and scatter reaching the IR, magnification, and spatial resolution? | OID |
| How is the primary beam affected when increasing the tube filtration? | increase in the proportion of higher energy XRs |
| What happens when the tube alignment is not parallel with the object and IR? | shape distortion |
| 3 primary exposure factors: | 1. mA 2. kVp 3. exposure time |
| (T/F): Changing the kVp affects the quantity and the quality of the beam. | True |
| A high kVp results in ___ variation in XR intensities exiting the pt | less |
| SOD can be determined by: | SID - OID |
| For every ___ of part thickness, the RT should adjust the mAs by a factor of 2 | 4-5 cm |
| The radiographic grid is located: | between the pt and the IR |
| Increased quantum noise is seen in a digital image with: | mAs that is excessively lower than needed |
| Increasing part thickness ___ radiographic contrast. | decreases |
| Magnification is affected by what 2 factors? | SID and OID |
| Increasing tube filtration results in an XRB with | higher energy and fewer photons |
| What effect will increasing SID have on spatial resolution? | increased spatial resolution |
| How much change in kVp will change the radiation exposure to the IR by a factor of 2? | 15% |
| (T/F): When choosing a grid for an exam, the grid with the highest grid ratio will improve contrast and decrease pt dose. | False- high ratio grid will increase pt dose |
| During selection of the focal spot size, the RT is really determining the: | actual size of filament used |
| What quality factor is not affected by a change in SID? | contrast |
| Decreasing collimation results in ___ scatter, ___ patient exposure, and ___ image contrast. | more; more; less |
| With all factors remaining the same, a pt with which body habitus requires the highest exposure factors? | hypersthenic |
Created by:
lipscombsomi