1. A method for positioning a mammal or part thereof for optical imaging, the method comprising: i) obtaining a digital image of a surface of the mammal comprising a ROI; ii) defining the ROI; iii) registering coordinates of the ROI with an optical imaging system having collection optics components; iv) positioning the mammal relative to an object plane of the collection optics based on said registered coordinates of said ROI such as to image the ROI.