A hospital patient has been given some ¹³¹I (half-life = 8.04 d) which decays at 4.2 times the acceptable level for exposure to the general public. How long must the patient wait for the decay rate to reach the acceptable level? Assume that the material merely decays and is not excreted by the body.

Question

Quizplus · Accepted Answer

The decay rate decreases by half every 8.04 days. To reduce the decay rate from 4.2 times to 1 time the acceptable level, the patient must wait for the decay rate to halve twice (4.2 -> 2.1 -> 1.05). This takes approximately 2 half-lives, or 16.08 days, which is closest to 17 days.

A Hospital Patient Has Been Given Some 131I (Half-Life =

A Hospital Patient Has Been Given Some ¹³¹I (Half-Life =