Question

1. Radioactive iodine, lodine 131, is used in Thyroid cancer therapies. Its half life is 8days. If a patients is given a total dose of 1 gram of lodine 131, how much will beleft in the patients blood stream after 32 days? 2. explain how you got that answer

Answer 1

The number of half-lives in 32 is given by:

$\frac{32}{8}=4$

After the 4 half-lives, the amount of iodine 131 left is given by:

$\frac{1}{2^4}=\frac{1}{16}$

Therefore, the amount left in the patients blood stream after 32 days is 1/16 g

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