Artifacts in radiographic imaging are discrepancies between the reconstructed visual image and the content of the subject. In radiographic imaging, this means the grayscale values in the image do not accurately reflect the attenuation values of the subject. Structures may also appear that do not exist in the subject. Whatever the source or appearance of image artifacts, their presence degrades the accuracy of the image in relation to the true characteristics of the subject. One should therefore be aware of the presence of artifacts and be familiar with their characteristic appearances in order to enhance the extraction of diagnostic information.