1. Apparatus comprising: an image acquisition mechanism that generates a plurality of images of an imaging target of an individual in a time series during a scan; an image processor that processes the plurality of images to generate processed images, wherein the processed images are at least one of projection images and reconstructed images; a computer which is configured to display the processed images and which detects and quantifies motion of the target of a magnitude of between about 70 μm to about 420 μm during the scan by comparing an actual location of at least one point of reference in each processed image with an expected location of the at least one point of reference derived from a set of the processed images and by generating a motion score, wherein the at least one point of reference is an intrinsic marker of the individual and wherein the intrinsic marker comprises a plurality of points along a skin line; and a mechanism for comparing the motion score to a threshold and for prompting a responsive action if the motion score exceeds the threshold.