CHAPTER 15
QUIZ ANSWERS:
1. b) Lead
2. b) Are high-speed electrons or positrons
3. c) 110 kV, 500 mA
4. a) Measure T1 and T2 relaxation times
5. a) True
6. b) Radioisotopes are injected into the body as nuclear medicines
PROBLEMS ANSWERS:
1. 1.4 heat units = 1 joule. 3000 heat units = 3000/1.4 joules = 2142.85 joules
2. Typically the safe limit is less than 2000 mrem per year
3. The exposure time varies with the current level (e.g., the time needed for 200 mA is
less than that needed for 15 mA). Typically, assume 2 seconds for 15 mA, and then for
the same mR, the time is 0.15 seconds for 200 mA.