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Ch. 10 Test RadBio
Radiobiology
Question | Answer |
---|---|
What are the factors that are most modifiable for radiation protection? | Time, Distance, Shielding |
What is the relationship between time and radiation exposure? (Equation) | directly proportional (I1/I2 = t1/t2) |
Of the three factors, which is the most effective means of reducing radiation exposure? | Distance |
What is the relationship between distance and radiation exposure/intensity? | intensity is the inverse of the square of the distance. ( I1/I2 = (D2/D1)squared) |
If the distance is cut in half, intensity will increase by a factor of... | 4 (4x the original density) |
If distance is doubled, the intensity will decrease by a factor of... | 4 (1/4 of the original density) |
If the distance decreased what happens to the intensity? | increases |
If the distance increased, what happens to the intensity? | decreased |
What is the relationship between mAs and intensity of radiation? equation | Directly proportional relationship (mAs1/mAs2 = I1/I2) |
What is the preferred material for shields? | lead |
How high must a primary barrier be? | 7 ft |
The control booth is considered what form of barrier? | a secondary barrier |
The ceiling is considered what form of barrier? | a secondary |
What is a primary barrier? | any wall or other barrier that is not strukh by the primary beam. |
What is a secondary barrier? | a barrier that may be struck by secondary/scatter radiation. |
What makes materials such as lead to have an increased attenuation? | high atomic weight |
A lead shield that may provide 97% attenuation at 50 kVp. How much will it provide at 100 kVp? | 50% |
What percentage should a 0.5 mm lead equiv. attenuate at 75 kVp? | 90% |
According to NCRP Report No. 102, what leads should be used in Flouroscopy? | 0.5 mm |
What is the average dose to the thyroid during a fluoro exam? | 6 mrad |
What is a mobile shield? | A shield that is not stationary and can be moved around the room. |
Define Cataractogenic. | Causing formation of cataracts. |
Lead glasses have what lead equiv.? | 0.75 mm |
What is the monthly dose allowed for a fetus according to NCRP No. 116? | 50 mrem (o.5 mSv) |