RTEC A – MORE “MATH” PROBLEMS
MAS, Dose & INVERSE SQUARE LAW - KEY
1. Using 400 mA and 0 .5 sec 2. Using 300 mA and 1/10
sec -
what is the mAs 200 MAS
what is the mAs 30 MAS
3. Using 600 mA and 100 msec - what is the mAs 10 MAS
(100 msec – 0.1 sec)
4. If the intensity of an x- ray beam measured 200 mr at 1 foot,
what would the intensity be at 4 feet? 12.5 mR
5. If the intensity of an x- ray beam measured 50 mr at 4 feet,
what would the intensity be at 2 feet? 200 mR
6. If the intensity of an x- ray beam measured 900 mr at 1
feet, what new distance would be required to change the intensity
to 100 mr?
3 feet.
7.
36 inch SID from tube – output was 100 mR
What is mR output if moved to 72”
25 mR
(insignificant to problem)
8. At 70 kvp. 40 mas and 72 inch SID –
tube output was 50 mR What is mR output if moved to 40”
without changing the technique (KVP or MAS)? 162 mR
9. At 1 foot from a source the output intensity is 600 mR What is
the exposure received when you move 2 feet away? 150 mR
10. The technologist received 50 mr of exposure at 1 foot for
5 min of the exam, then moved 5 feet from the patient and
remained an additional 5 minutes. How much exposure did the
technologist receive for this procedure when they moved to the
new distance?
2 mR &
What was the TOTAL exposure for the exam? 50mR + 2 mR =
52mR