This report of the National Council on Radiation Protection and Measurements (NCRP) , successor to the National Committee on Radiation Protection and hleasurements, is concerned with the spccification of sealed sources of nuclides which emit gamma rays-sources useful in brachytherapy. The report resulted from the Council's belief that a single well-defined method for specifying the radionuclide in an encapsulated source would be advantageous for both the users and the suppliers of such sources
