Radioactive iodine 133I has a half-life of 20.9 hours. If injected into the bloodstream, the iodine accumulates in the thyroid gland.

a. After 24 hours, a medical technician scans a patient’s thyroid gland to determine whether thyroid function is normal. If the thyroid has absorbed all the iodine, what percentage of the original amount should be detected?

b. A patient returns to the medical clinic 25 hours after having received an injection of ¹³³I. The medical technician scans the patient’s thyroid gland and detects the presence of 41.3% of the original iodine. How much of the original ¹³³I remains in the rest of the patient’s body?