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chap 26 density
Imaging1.
| Question | Answer |
|---|---|
| What is the human visibility density range? | .25-2.50 |
| What is brightness? | monitor control function that can change the lightness and darkness of the image on a display screen. Luminosity intensity. |
| What is the window level? | Digital post processing that produces changes in brightness. Controls brightness. |
| What is the controlling factor for density/IR exposure? | mAs |
| Density and time have what relationship? | Directly proportional. |
| The factor that determines the total quantity of x-rays produced in a beam is the? | mAs |
| The length of x-ray exposure is determined by the? | time |
| Time controls or influences what? | Density. |
| Density and mAs have what relationship? | Directly proportional. |
| mA controls/influences what? | Density |
| What factor is the amount of current in the x-ray tube at the time of exposure? | mA. Amperage is the unit of current. |
| What does kilovoltage change? | Contrast. |
| To cause a visible shift in denity, what percent of mAs or influencer should be used? | 30% |
| mAs changes generally go in increments of what? | doubles or halves |
| Kilovoltage controls the average ____________ produced at the anode target. | energy of the x-ray photons |
| Why does kVp have an impact on density/IR exposure? | kV alters the intensity of the beam when mAs and other factors stay the same, therefor both the quantity and the quality of the x-ray beam vary significantly with kV changes. |
| The 15 percent rule is used for what? | Maintaining the same density/exposure when kV changes. |
| a 15% increase in kV causes _____ exposure to the IR. | Doubling |
| a 15% decrease in kV would _____ the IR exposure. | Half. |
| A single-phase waveform has lower average photon energy, resulting in what kind of exposure? | A less dense IR exposure |
| Anode heel effect alters what? | The radiation intensity, so the density. |
| What does the inverse square law express? | the change in intensity when the distance changes. |
| According to the inverse square law, as distance increases, radiation intensity... | and IR exposure/density decreases in 4 directions. |
| According to the exposure maintenance formula… To maintain IR exposure, what must happen when distance increases? | mAs must increase |
| How does beam restriction affect density? | Collimating or reducing the beam size reduces the # of photons, this reduces the amount of scatter radiation. |
| What is the relationship between tissue and density? | Inverse. |
| As relative speed (RS) increases, what happens to the amount of exposure required to maintain density? | it decreases. |
| How does the inverse square law differ from the exposure maintenance formula? | the inverse square law expresses intensity change. ex) distance increases, intensity and exposure decrease. The maintenance is reversed. ex) distance increases, mAs must increase. |
| What happens to density if you increase filtration? | Inverse relationship. Adding filtration absorbs more low quality photons, resulting in a better quality beam and decreasing exposure-decreasing density. |
| What happens to density if you decrease the grid ratio? | Density increases. |
| If you decrease the OID what happens to density? | Increases. |
| Increasing beam restriction/collimation does what to density? | Decreases density. |
Created by:
Zoest35
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