Radioactive iodine treatment is so successful at treating hyperthyroidism that it has virtually replaced thyroid surgery. To the nearest full day, determine how long it will take for 400 millicuries of I-131, which has a half-life of 8 days, to decay to 3.125 millicuries.
Is it just 131/8 until you get to 3.125?
Anonymous
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no, the I-131 is the name of the radioactive iodine, the I stands for iodine and the 131 is the radioactive number.
the patient would start with 400 millicuries of the iodine in his body, after 8 days (the half life) this would have dropped to 200, another 8 days it would be 100 and so on.
day 1 = 400
day 8 = 200
day 16 = 100
day 24 = 50
day 32 = 25
day 40 = 12.5
day 48 = 6.25
day 56 = 3.125
so it would take 56 days to decay to 3.125 millicuries