The TDCR method as an important tool in radionuclide metrology

The paper presents Triple-to-Double Coincidence Ratio (TDCR) method as an important tool in radionuclide metrology for standardizing pure β- and pure EC-radionuclides. Many metrological laboratories in the world are using this method. The TDCR method was adapted to the international reference system (SIR) in the Bureau des Poids et Mesures (BIPM) in Sevres and establish a part of the National Standard of Radionuclides Activity Unit in Poland. The principles of the TDCR method and the measurement device based on the Liquid Scintillation Counting (LSC) are described. An example of results of standardization and a list of radionuclides measured by the TDCR method are given. Applying of the method for standardizing radiopharmaceuticals and preparation of standards for detectors calibration for environmental and nuclear medicine purposes is pointed out. (author)