The greatest concentration of iodine in the body is in the thyroid gland, so radioactive iodine-131 is often used as a tracer to help diagnose thyroid problems. Suppose the activity of ¹³¹I in a patient's thyroid is initially 1.85 10⁶ Bq. ¹³¹I decays via beta radiation with an average energy of 180.0 keV per decay. Calculate the absorbed dose in sieverts the patient's thyroid receives in the first hour of exposure. Assume that half of the radiation is absorbed by the thyroid gland, which has a mass of 150.0 g.The relative biological effectiveness for beta radiation is 1.00 Sv/Gy.

The asnwer is 6.40E-4 Sv.

But I do not know how to get that answer all the ways i have calculated do not get me within the 1% error range required for me to receive credit i have been at this for 3 days the instructor doesn't explain very well after multiple requests