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171 test #2
| Question | Answer |
|---|---|
| Includes two or three sets of lead shutters, some of which are adjustable: | Collimator |
| A device consisting of very thin lead strips with Radiolucent interspaces intend to absorb scatter radiation emitted from the patients: | Grid |
| A larger the x-ray beam field size result in: | Increase in scatter and fog |
| Decreasing patient thickness while using AEC would result in: | Decreased exposure time |
| As collimation decreases, exposure the Ir increases: T/F | True |
| Digital IRs are not sensitive to scatter radiation: T/F | False |
| What happens to density as SID increases? | Density decreased |
| Why does the air-gap technique work? | The scatter photons are more likely to miss the image receptor |
| Significant collimation requires an increase of the mAs | |
| During Operation of the AEC device, the time of exposure: | Inversely related to the intensity in exit radiatiom |
| What factors are important when using AEC devices? | Detector, centering and back-up mAs |
| What is the primary goal of exposure technique charts? | Consistency in image quality |
| What type of exposure technique system uses a fixed mAs regardless of patient thickness? | Variable kVp |
| Using a higher kVp during an AEC examination results in? | A shorter exposure time |
| Density represents the different absorption characteristics of the body T/F | True |
| AEC device work by measuring the: | Radiation that exits the patients |
| Detectors to select ionization chamber phototimer vs Ionazation chamber: | AEC |
| Different from AEC anatomic area selection that tech can adjust technique once selected: | (APR) anatomically programmed radiography |
| Two types of AEC systems: | Phototimer and ionizing chamber |
| AEC exposure factors for each type of radiographic examination are called: | Exposure technique charts |
| Advantages of fixed kVp-variable mAs technique chart include: | Easier to use, more consistency and uniform contrast |
| Adding a grid or increasing grid ratio results in an increase in patient dose: True/false | True |
| Grids absorb all of the scatter radiation and allow all of the transmitted photons to pass through to the IR: True/false | False |
| When using automatic collimation, collimating to the anatomy of interest is an unnecessary waste of time; the beam is already collimated: True/False | False |
| Scatter radiation reaching is of no value in radiographic imaging: True/False | True |
| Absorption of transmitted photons by a grid caused by misalignment is: | Grid cut off |
| The recommended SID that can be used with focused grid is the: | Focal range |
| To compensate for the reduction of radiation reaching the IR when a grid is used,_____is typically increased? | mAs |
| A focused grid’s strips are angled to match: | The angle of the x-rays in the primary beam |
| The purpose of automatic collimation is: | Limiting patient exposure |
| The field shape produced by a collimator is: | Rectangular |
| The volume of tissue irradiated is determined by: | Area of collimation, patient thickness and field size |
| The two factors that affect the amount of scatter radiation production produced and exiting the patient are: | Volume of tissue irradiated and kVp |
| The probability of a Compton interaction occurring is related to: | Energy of the x-ray photon |
| For radiographic procedures, scatter radiation is primarily the result of: | Compton interaction |
| The primary source of radiation exposure to the radiographer who is in the room during exposure is: | Scatter from the patient |
| The effective focal spot is: | Smaller than the actual focal spot |
| What happen to absorption as kVp increase: | decrease |
| The shape of the unrestricted primary beam field | Circular(cone shaped) |
| Radiation transmitted through patient to the AEC occurs: | X-ray exposure terminates |
| Works by using gas-filled chamber: | Ionization chamber |
| Use by converting x-ray photons to light then into an electronic signal: | Phototimer |
| Exposure variable controlled by AEC | Seconds |
| Using AEC the radiographer adjust to manipulate the subject contrast of the image: | kVp |
| Purpose of setting a back-up time/mAs: | To prevent excessive exposure of the patient |
| In order to be familiar with manual technique factors, it is very helpful to pay attention to the: | mAs readout |
| When using a fixed kVp-variable mAs technique chart, if part thickness increase by 5cm, what needs to happen to the mAs? | It should be doubled |
Created by:
Faithshay