Accurate delineation of the primary tumor and of involved lymph nodes is a key requisite for successful curative radiotherapy in non-small cell lung cancer (NSCLC). In recent years, it has become clear that the incorporation of FDG PET-CT scan information into the related processes of patient selection and radiotherapy planning has lead to significant improvements for patients with NSCLC. The use of FDG PET-CT information in radiotherapy planning allows better target volume definition, reduces inter-observer variability and encourages selective irradiation of involved mediastinal lymph nodes. PET-CT also opens the door for innovative radiotherapy delivery and the development of new concepts. However, care must be taken to avoid a variety of technical pitfalls and specific education is necessary, for clinicians and physicists alike. (C) 2011 Elsevier Ireland Ltd. All rights reserved.