 The primary aim of this study is to investigate whether sampling a small volume of blood using a lancet and pipette can replace standard intravenous blood samples for bone marrow dosimetry in patients undergoing radioiodine treatment for thyroid cancer. Statistical tests will determine whether there is a significant difference between the doses calculated using each blood sampling method. In addition, the investigators will measure the radiation exposure received by the operator during each procedure using Electronic Portable Dosimeters. The results of these measurements will be used to quantify the reduction in operator radiation exposure afforded by the new technique. 