Professor Joerg Lehmann is an accredited Radiation Oncology Medical Physicist at Calvary Mater Newcastle, where he serves as Lead Medical Physicist for Research.

His research focuses on dosimetry, quality assurance, image guidance for radiotherapy, and data mining.
Joerg leads a project to enhance the sensitivity of clinical quality assurance systems to improve radiation oncology treatments (SEAFARER). This project involves an international team from Australia, the UK, and the US, closely collaborating with the National Physical Laboratory in the UK.

He also heads a project developing a system for continuously and directly measuring internal anatomy to guide breast cancer radiation treatment during deep inspiration breath hold, which is currently trialled in the clinic.

Professor Lehmann is involved in several international working groups, including a joint task group of the American Association of Medical Physics (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) on performance validation of surrogate assessment systems (TG 360). He is a member of the AAPM Global Research and Scientific Innovation Committee and serves as Chair of the Global Clinical Trials Subcommittee.

As a physicist for the Transtasman Radiation Oncology Group (TROG), Professor Lehmann contributes to radiotherapy dosimetry audits and quality assurance. He previously chaired the Global Quality Assurance of Radiation Therapy Clinical Trials Harmonisation Group (GHG), which standardises and improves quality assurance across multi-institutional clinical trials.