The National Calibration Reference Centre for Bioassay and In Vivo Monitoring (NCRC) is committed to improving workplace safety by providing high quality intercomparison programs for the measurement of internal radiation exposures of workers. The Centre was established in 1982 within the Radiation Protection Bureau (RPB), Health Canada, to provide a national calibration reference service to universities, hospitals, public utilities and private firms. The main purpose of the reference service is to ensure that measurements of internal radiation doses to workers are accurate.