Presentation Transcript
Chapter 4 :Chapter 4 Ben Weisman
Thursday, September 14, 2006
NMT1002
Group Three
Chapter 4 Section 2 :Chapter 4 Section 2 Problem #6
If a source reads 1.03 mCi in a dose calibrator when the expected activity is 0.96, can the instrument be used according to NRC standards?
Answer :Answer Yes
You must calculate the percent error and compare it to the limit of 10% to find out whether this particular dose can be used.
Percent error = l expected reading – actual reading l x 100%
expected reading
Calculation :Calculation On the TI-30X SOLAR, subtract 1.03 from 0.96 and take the absolute value of your answer (0.07) and divide by 0.96 (0.0729). To make this a percent value, multiply by 100 to get 7.29%.
Since this value (7.29% < 10.0%) is acceptable by the NRC standard, this particular dose can be utilized in this procedure
Chapter 4 Section 14 :Chapter 4 Section 14 Problem # 3
How many mCi should be added to a phantom to obtain a counting rate of 20,000 cpm if a 520 uCi sample of solution produces 8,740 cpm?
Answer :Answer 1190 uCi
To determine the activity needed for phantom preparation use the proportional equation,
test sample counting rate = phantom counting rate
test sample activity phantom activity
8740 cpm = 20000 cpm
520 uCi ? uCi
Answer Continued :Answer Continued Solve for ? by cross multiplication
On TI-30X SOLAR, Press 20000 X 520, then = (1.04E7). Divide your answer (press /) by 520 to get the amount of phantom activity (1190).