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Imaging1 chap 11
Imaging1. Prime Factors
| Question | Answer |
|---|---|
| Unit of measurement for x-ray quantity? | Roentgen |
| What are the 4 factors that directly affect x-ray quantity? | mAs, kV, distance, filtration |
| What are the prime factors? | mAs (quantity), kVp (quality), distance |
| What are the 2 factors that directly affect x-ray quality? | kV and filtration |
| X-ray quality is numerically represented by the ____. | half-value layer (HVL). |
| What is the HVL? | The HVL of an x-ray beam is that thickness of absorbing material needed to reduce the x-ray intensity (quantity) to half it's original value. |
| What is mA? | measurement of x-ray tube current, the number of electrons crossing the tube per second. |
| mA is quantity or quality? | Quantity. |
| what is mAs? | unity used to describe the product of tube current (mA) and exposure time (seconds) |
| When calculating the relationships between distance and x-ray intensity, what mathematical expression should be used? | Inverse square law. i1 over i2 = D2 over D1 (intensity is mR) |
| Reciprocity law is? | IR exposure should remain unchanged as long as the intensity and duration of the x-ray exposure remains unchanged. (80mA @ .04 seconds is the same as 160mA @ .02 seconds) |
| Increasing the kilovoltage will cause an increase in the ___ and ___ of the electrons. | speed and energy |
| kV affects the quantity because? and it affects the quality because? | quantity- because more interactions occur at the target as kVp increases, and quality because each electron has more energy, resulting in a beam with greater penetrability. |
| quantity (kVp) is approximately directly proportional to the ______.. | square of the ratio of the change in kVp. (as Kvp is doubled, the amount of x-ray photons increases about 4 times) |
| If kVp is decreased by 15%, expsore will be what? | reduced by one-half. |
| If minting the exposure is desired, decreasing the kVp by 15% should be accompanied by what? | doubling the mAs. |
| What is the exposure maintenance formula? | mAs1 over mAs2 = D1 over D2 |
Created by:
Zoest35
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