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Ch 567
| Question | Answer |
|---|---|
| All of the following are radiographer operated controls | kVp, mA and time |
| The diagnostic xray range is approx | 25 to 150 kVp, 10 to 1200 mA, 0.001 to 10 seconds |
| To protect the radiographer during xray exposures | The mA and kVp selections are on the low voltage side of the circuit |
| A three-phase, rectified current produces a voltage ripple of | 6 pulses per Hz |
| Falling load generators | permit higher mA exposures for short exposure times, permit the mA to fall as exposure time increases, are designed to use the highest allowable mA |
| When compared to battery-powered portable radio-graphic units, capacitor discharge mobile units | have a tendency to produce leakage exposure after exposure termination |
| What is the leakage radiation limit | 100mr/hr @ 1 meter |
| Why is a vacuum created in the xray tube? | To keep oxygen atoms and other particles out so they can not interfere with the flow of electrons |
| Single phase generators have a voltage ripple of | 100% |
| A high frequency generator has a voltage ripple of | 3-4% |
| The heterogeneous characteristics of xrays is due to: | Bremsstrahlung interaction |
| Milliamperage second (mA) directly affects: | beam quality, beam intensity, xray output |
| The factors that directly affect xray quantity are: | mA and time |
| Xray beam quality is numercially represented by the | HVL (Half Value Layer) |
| As the mA doubles, the number of electrons flowing from the cathode to anode | increase twofold |
| The product of tube current and exposure time is equal to | xray beam quantity |
| If the mAs of a radiograph is increased from 10 to 20, the resulting radiograph will exhibit | increased radiographic film density |
| Increasing the kVp for an exposure will | cause the electrons to travel faster from the cathode to anode |
| Kilo-voltage is the primary controlling factor of: | radiographic film contrast |
| An increase in kVp by 15% will cause an approx ------ in the exposure | doubling |
| Adjustments in kVp should be used to control radiographic: | contrast |
| Xray beam penetrability is primarily controlled by: | kVp |
| The relationship between the intensity of radiation and distance is the: | Inverse square law |
| The length of the exposure time for a radiograph, is used to primarily control | motion |
| The brightness of the image on a viewing monitor is | a function of the monitor |
| The principal controlling factor of radiographic image density is | mAs |
| Which rule is used as a guide to maintain the same density when kVp changes? | 15% rule |
| Which factor influences the number of photons reaching the IR? | mAs |
| Which factor influences the average energy of photons reaching the IR? | kVp |
| The 15% rule changes | density and contrast |
| The relationship between exposure and SID is | inversely proportional to the square of the distance |
| The greatest factor in the production of scatter radiation is | `patient thickness |
| Because of the "heel effect", xray beam intensity | is greater under the cathode side of the tube |
| The most commonly used silver halide is silver | bromide |
| Given 25 mAs and a milliamperage of 100, calculate the exposure time | .25ms |
| Given an exposure time of 0.06 second and a mA of 400, calculate the mAs | 24 mAs |
| Where is filtration located | In the xray tube |
| What material do we use for filtration | aluminum |
Created by:
ehalbhuber