Astatine (211At) as a therapeutic radionuclide. The plasma:blood cell distribution in vitro

Therapy of carcinoma of the thyroid may include the use of the radionuclide 131I, which localizes to thyroid tissue. In considering the use of another halogen, the alpha particle emitting radionuclide astatine, 211At, there is also the requirement that it too can be taken up by the thyroid. However, in view of its short half-life (7.2 h) it is important that its transport in the blood is not a factor likely to render it less available. For example, retention of 211At by red cells may retard its uptake by the thyroid. This in vitro investigation of the partitioning of the 211At between erythrocytes and plasma indicates that it is not strongly bound by the red cells in blood.