  This note addresses the problem of spurious poles in gauge-theoretic
scattering amplitudes. New twistor coordinates for the momenta are introduced,
based on the concept of dual conformal invariance. The cancellation of spurious
poles for a class of NMHV amplitudes is greatly simplified in these
coordinates. The poles are eliminated altogether by defining a new type of
twistor integral, dual to twistor diagrams as previously studied, and
considerably simpler. The geometric features indicate a supersymmetric
extension of the formalism at least to all NMHV amplitudes, allowing the
dihedral symmetry of the super-amplitude to be made manifest. More generally,
the definition of `momentum-twistor' coordinates suggests a powerful new
approach to the study of scattering amplitudes.
