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Exposure Factors
Chapter 12 - Prime factors
Question | Answer |
---|---|
What are the three prime factors that affect x-ray emission? | milliamperage-second (mAs), kilovoltage (kVp), and distance (d) |
The unit of measurement for x-ray quantity? | the roentgen (R) |
Equal to an electric charge of one Coulumb flowing through a conductor per second | an ampere |
What is the relationship between mAs and IR exposure? | As mAs increases, x-ray exposure to the image receptor increases porportionally. |
What effect does increased kVp have on the speed and energy of the electrons in the x-ray tube? | increasing kilovoltage will cause an increase in the speed and energy of the electrons across the x-ray tube. The more quickly the electrons move across the cathode to anode, more electrons reach the target per second, resulting in an increase x-rays. |
The intensity of radiation at a given distance from the point source is inversely proportional to the square of the distance | inverse square law |
X-ray exposure is inversely proportional to the square of the distance. As a result, if distance is increased, image receptor exposure will ______. | decrease |
What is the measurement of the penetrating ability of the x-ray beam? | x-ray quality |
What is the product of the tube current and exposure time? | milliamperage-second (mAs) |
What kilovoltage (kVp) is needed to double the exposure of a femur at 15 mAs at 60kVp? | Increased by 15% |
What would the kilovoltage (kVp) be to double the exposure of a femur at 15 mAs at 60 kVp? | 69 kVp |
What is considered to be the main controller of radiographic film density? | mAs |
A direct relationship is necessary to compensate for the changes in intensity and film density | direct square law |
A direct square law; mAs must increase when distance increases, and vice verse, in order to maintain image receptor exposure | exposure maintenance formula |
The ability of the x-ray to pass through structures and tissues. | penetrability |
Factors related to x-ray emission that are under the direct control of the radiographer; milliamperage, kilovoltage, and distance. | prime factors |
A measurement of the penetrating ability of the x-ray beam | x-ray quality (kVp) |
A measure of the number of x-ray photons in the useful beam | x-ray quantity (mAs) |
Exposure Factors Chapter 12 - Prime Factors |