  In this paper we study the linearized inverse problem associated with imaging
of reflection seismic data. We introduce an inverse scattering transform
derived from reverse-time migration (RTM). In the process, the explicit
evaluation of the so-called normal operator is avoided, while other
differential and pseudodifferential operator factors are introduced. We prove
that, under certain conditions, the transform yields a partial inverse, and
support this with numerical simulations. In addition, we explain the recently
discussed 'low-frequency artifacts' in RTM, which are naturally removed by the
new method.
