The current standard of care for small cell lung cancer is combined-modality therapy, including the use of chemotherapy, surgery (in selected cases of limited stage of disease), and radiation therapy. This review will focus on the role, dose fractionation, technology and timing of thoracic radiation, and the role and dose regimen of prophylactic cranial irradiation for both limited and extensive stage of diseases. Consensus recommendation from experts is summarized in the tables for 2 typical case scenarios. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.