Multi-modality imaging has become increasingly prevalent in nuclear medicine and diagnostic radiology. To accurately interpret single photon emission computed tomography/computed tomography (SPECT/CT) images in addition to understanding the principles of image formation and the biological distribution of the radiopharmaceutical, it is important to understand the image artefacts that can arise from these imaging systems. This atlas presents an overview of quality control procedures in SPECT and SPECT/CT and guides the reader through pitfalls and image artefacts that can be faced using these imaging modalities. In addition to examples of artefacts themselves, descriptions are given on their causes, and the steps that can be taken to avoid their recurrence. The atlas is intended to be used as a guide for nuclear medicine and diagnostic radiology professionals (medical physicists, nuclear medicine physicians, radiologists, medical radiation technologists and service engineers) on how to take appropriate quality control measures, and to assist with problem analyses and prevention.