11-5. A series of radioactive sample of short half-life will be counted

one per day over a period of several days. Explain how variations

in the observed counts caused by fluctuations in the sensitivity

of the counting system can be compensated.

12-1. The uptake of 131I was measured for a patient treated for hyperthyroidism

with the same radioactive nuclide 2 months previously.

The count rates were as follows:

For a 131I standard on day 0                                   13,260 cpm

For a 131I standard 24 hour later                            12,150 cpm

For the patient on day 0 before 131I                                    6,140 cpm

administered

For the patient 24 hours later                                12,840 cpm

Compute the percent uptake of 131I in the thyroid gland. Ignore

the contribution of background radiation to the count rates, but

include the contribution from residual 131I.