Described herein is an approach to determine a deflection of a portion of an imaging system tabletop located at iso-center utilizing a tabletop deflection determiner with a least a first portion located on a rotating gantry portion of the imaging system. In one non-limiting instance, an imaging system includes a rotating gantry portion (606) with an aperture defining an examination region, a tabletop (620) that supports a subject or object in the examination region, wherein the tabletop cantilevers into and deflects in the examination region, and a tabletop deflection determiner (622) that determines a deflection of the tabletop in the examination region, wherein a first portion (702, 706) of the tabletop deflection determiner is located on the rotating gantry portion.