RT Journal Article T1 Implementation of dosimetry in molecularradiotherapy in Spain. Results from a Spanish survey A1 Moya, Estrella A1 Cerrato, Cerrato A1 Bedoya Del Olmo, Luis Miguel A1 Guerra Guirao, José Antonio AB Purpose: The use of molecular radiotherapy (MRT) has been rapidly evolving over the last years. The aim of this study was to assess the current implementation of dosimetry for MRTs in Europe.Methods: A web-based questionnaire was open for treating centres between April and June 2022, and focused on 2020-2022. Questions addressed the application of 16 different MRTs, the availability and involvement of medical physicists, software used, quality assurance, as well as the target regions for dosimetry, whether treatment planning and/or verification were performed, and the dosimetric methods used.Results: A total of 173 responses suitable for analysis was received from centres performing MRT, geographically distributed over 27 European countries. Of these, 146 centres (84 %) indicated to perform some form of dosimetry, and 97 % of these centres had a medical physicist available and almost always involved in dosimetry. The most common MRTs were 131I-based treatments for thyroid diseases and thyroid cancer, and [223Ra]RaCl2 for bone metastases. The implementation of dosimetry varied widely between therapies, from almost all centres performing dosimetry-based planning for microsphere treatments to none for some of the less common treatments (like 32P sodium-phosphate for myeloproliferative disease and [89Sr]SrCl2 for bone metastases).Conclusions: Over the last years, implementation of dosimetry, both for pre-therapeutic treatment planning and post-therapy absorbed dose verification, increased for several treatments, especially for microsphere treatments. For other treatments that have moved from research to clinical routine, the use of dosimetry decreased in recent years. However, there are still large differences both across and within countries. PB Elsevier YR 2025 FD 2025-03-20 LK https://hdl.handle.net/20.500.14352/125147 UL https://hdl.handle.net/20.500.14352/125147 LA eng NO Moya E, Cerrato C, Bedoya LM, Guerra JA. Implementation of dosimetry in molecularradiotherapy in Spain. Results from a Spanish survey. Radiation Physics and Chemistry 2025;234:112717. https://doi.org/10.1016/j.radphyschem.2025.112717. DS Docta Complutense RD 18 dic 2025