Purpose: Diagnostic imaging, including ionizing radiation modalities, maintains a prominent role in the medical evaluation of patients. There is increasing awareness and need for information across varied sectors about low-level radiation and potential risks. Many medical and scientific organizations have resources discussing radiation risk and management. However, there is no single resource compiling this information. Methods: Websites, including those of national and international medical organizations, were reviewed for information on radiation dose, risk, justification, optimization, guidelines (including general information about improvement in quality and dose reduction without specific mention of optimization techniques), appropriateness criteria, and general principles of radiation safety for CT, fluoroscopy or angiography, and radiography. This information was organized into 8 tables, categorized by modality, and separated for adult and pediatric populations. Websites with training modules were noted as well. Results: Twenty-nine websites were explored. Overall, less information is available about medical radiation safety in children compared with adults. Across both groups, most information is available on CT, then fluoroscopy, and finally radiography. Across all groups and modalities, there is no information available for patients or parents on optimization, appropriateness, or guidelines, with the exception of adult radiography, for which there are some guidelines. Conclusions: This compendium serves as a collective resource for communities including the public and regulatory organizations. Additionally, the compendium can be used to determine redundant or deficient areas, providing opportunities for more comprehensive resources and efficient efforts in accessing medical radiation patient safety information.