The overall objective of the project is to establish traceability routes for nuclear medicine services across several European countries. The specific objectives of the project are: To establish traceability routes to provide traceable calibration services for key radionuclides with an uncertainty (at k = 1) of 2 % or better. The services will be developed in collaboration with the local responsible NMI/DI and partner hospitals to ensure a functional service that will operate effectively within the legislative requirements of the host country. To assess and develop uncertainty evaluation methods used by calibration laboratories and clinical users to provide practical support for end-to-end uncertainty evaluation from activity determination at the calibration laboratory to quantitative imaging and dosimetry. To validate effectiveness of calibration routes and to assess measurement capability by performing comparison exercises among users for key clinical radionuclides. The target is for 80 % or more of participants from countries with emerging metrology capabilities in this field to be able to measure activity to within 10 % of the reference value. A supplementary target is to receive uncertainty budgets from 70 % or more of participants. To provide guidance documents on establishing calibration services for key radionuclides, validation of measurements and uncertainty assessment to further improve the accessibility of traceable calibration routes in Europe. To facilitate the take up and long-term operation of the capabilities, technology and measurement infrastructure for nuclear medicine measurements developed in the project, by the measurement supply chain (NMIs/DIs, calibration and testing laboratories), and end users (e.g. industry, instrument manufacturers, regulators). The approach should be discussed within the consortium and with other EURAMET NMIs/DIs, e.g. via EURAMET TC-Ionising Radiation (IR) and EMN for Radiation Protection, to ensure that a coordinated and optimised approach to the development of traceability in this field is developed for Europe as a whole.