An apparatus and method for providing a projection image directly from
data acquired by a CT scanner, the method comprising: acquiring an amount
of data corresponding to an entire object that is scanned by the CT
scanner, wherein the amount of data is generated by an x-ray source that
projects a fan beam of x-rays toward a detector array on an opposite side
of a gantry of the CT scanner as the object is passed through an opening
in the gantry; selecting an imaging plane, the imaging plane
corresponding to a view of the object; dividing the imaging plane into a
plurality of rows and columns, thus creating a grid of points
corresponding to the imaging plane; determining, for each point in the
grid, a data point from the acquired data corresponding to an x-ray
source position wherein a ray from the x-ray source to the grid point is
closest to a perpendicular orientation with respect to the imaging plane,
and a detector position where the ray intersects the detector array; and
presenting a projection image corresponding to the selected imaging
plane, wherein the projection image comprises a plurality of projection
points and each projection point in the projection image is a converted
value of the data points of the data points of the acquired data.