  We study theoretically phonon-assisted spin relaxation of an electron
confined in an elliptical quantum dot (QD) subjected to a tilted magnetic
field. In the presence of both Rashba and Dresselhaus spin-orbit terms, the
relaxation rate is anisotropic with respect to the in-plane field orientation.
This anisotropy originates from the interference, at nonzero tilt angle,
between the two spin-orbit terms. We show that, in a narrow range of magnetic
field orientations, the relaxation rate exhibits anomalous sensitivity to
variations of the QD parameters. In this range, the relative change in the
relaxation rate with in-plane field orientation is determined {\em solely} by
the spin-orbit coupling strengths and by the dot geometry. This allows
simultaneous determination of both Rashba and Dresselhaus coupling parameters
and the dot ellipticity from analysis of the angular dependence of the
relaxation rate.
