  The basic structure of top-quarks as spin-1/2 particles is characterized by
the radius $R_t$ and the intrinsic magnetic dipole moment $\kappa_t$, both
individually associated with gauge interactions. They are predicted to be zero
in pointlike theories as the Standard Model. We derive upper limits of these
parameters in the color sector from cross sections measured at Tevatron and LHC
in top-pair production $p{\bar{p}}/pp \to t{\bar{t}}$, and we predict improved
limits expected from LHC in the future, especially for analyses exploiting
boosted top final states. An additional method for measuring the intrinsic
parameters is based on $t \bar{t} + jet$ final states.
