A radiation worker stands 50 cm away from a radioactive source of 25 mCi 57Co. Calculate the exposure value received by the worker while standing for 1 hr near the source. The isotop half-life is 271.8 days.

A 75 kg patient swallows a 33 μCi beta emitter whose half-life is 5.0 days and whose RBE is 1.6. The beta particles are emitted with an average energy of 0.35 MeV, 90% of which is absorbed by the body. You are a health care worker needing to find the patient's dose equivalent after one week. These series of steps will help you find that dose equivalent. In all questions, assume the radioactive nuclei are distributed throughout the patient's body and are not being excreted. Part A How many radioactive nuclei did the patient swallow? Express your answer using three significant figures. ▸ View Available Hint(s) No= ΜΕ ΑΣΦ Submit ?

A 228Th source is labeled 1.50 mCi, but its present activity is found to be 1.73 ✕ 106 Bq. A.)  What is the present activity in mCi? =______mCi B.) How long ago did it actually have a 1.50-mCi activity? =_____y

A radiopharmaceutical is labeled with an activity of 480 mCi on April 1 at 6:00am. What is the activity of the formulation in mCi at 6:00am on April 10? The half life of the radioisotope is 8.10 days. Report to the nearest tenth, number only. λ=2.303/t (logN0/N)