Question

Suppose a patient is given 140 mg of I−131, a beta emitter with a half-life of 8.0 days.Assuming that none of the I−131 is eliminated from the person's body in the first 4.0 hours of treatment, what is the exposure (in Ci) during those first four hours?(give correct solution)

Answer 1

Answer: According to the question , Here the

Four hours is = 4 hours / (8*24) hours = 0.0208 half-lives.

Now , in after 4 hours we have = 0.0208 * 70 mg of I-131

= 1.96 mg

Hecne the after 4 hours the reaming amount is = 140 - 1.96 = 138.04 mg of I- 131

this means that 1.96 mg of I-131 released a beta particle .

Now , The number of mg divided by 1000 (to give grams), then divided by 131 (the atomic mass) will give the moles of Iodine. Multiply the moles by 6.022 * 10^23 to get the number of atoms of I-131 which decayed during the 4 hours.

Hence we get = 9.010 * 10¹⁸  atoms

Hence it is all about the given question . Thank you :)