Patent ID: 7336760

Claim:
A method of estimating scattered radiation in radiographic projections of an object, the radiographic projections generated by a radiation source, a two-dimensional imaging device adapted to measure incident radiation at a plurality of pixels and disposed opposite the source of radiation along a projection line and spaced therefrom to provide a space for the object to be imaged, a mechanism located closer to the radiation source than the imaging device and adapted to vary the source radiation incident upon the imaging device between at least a first band of pixels and a second narrower band of pixels, a scan axis that intersects the projection line and to which an object is aligned in a substantially fixed relationship, a relative rotation between the projection line on the one hand and the scan axis and an object aligned thereto on the other hand, the relative rotation being measured by an angular displacement value, the angular displacement value being effected by a rotation of the projection line with respect to the scan axis, a rotation of the object and the scan axis with respect to the projection line, or both such rotations, the method comprising the steps of: (a) obtaining a first group of radiographic projections taken by the two-dimensional imaging device at a corresponding first plurality of angular displacement values, the projections of the first group being taken with radiation from the source incident upon a first band of pixels of the imaging device; (b) obtaining a second group of radiographic projections taken by the two-dimensional imaging device at a corresponding second plurality of angular displacement values, the projections of the second group being taken with the radiation from the source incident upon a second band of pixels of the imaging device, the second band being narrower than the first band; (c) generating a first set of estimates of the scattered radiation within at least a portion of the second band of pixels for a third plurality of angular displacement values, each estimate of the first set being for a particular angular displacement value of the third plurality and comprising a difference between a first representation of the radiographic projection data taken with the source radiation incident upon the first band of pixels and a second representation of the radiographic projection data taken with the source radiation incident upon the second band of pixels, the first representation being generated from the at least one radiographic projection of the first group, and the second representation being generated from at least one radiographic projection of the second group.