APPARATUS AND METHOD FOR TRANSVERSE TOMOGRAPHY

摘要

An apparatus and method for generating a two-dimen-sional back-projected image of a slice of an object wherein a carrier having parallel elongated projections each having an optical characteristic (transmissivity or reflectivity) representing the density characteristic of the slice of the object as measured at a particular relative rotational angle. Successive sinusoidal patterns are imaged on the carrier at a predetermined rate. A display or recorder synchronized at the predetermined rate, is responsive to the output of a photodetector for displaying the back-projected image. In a preferred embodiment of the invention the carrier is a cylindrical film having projections with transmissivities that represent the density characteristic of the slice of the object under consideration. In this embodiment, a device unformly illuminates projections and an optical mask is provided in spaced relation to the cylindrical film and operative to image portions of the projections on the cylindrical film. The cylindrical film is rotated on its axis so that the mask means continuously images different groups of projections on the film. The relative angular motion between the mask and the axis of the cylindrical film is varied, whereby the mask continuously images varying portions of the cylindrical film, the variation being along the axial direction thereof. In this embodiment the display is synchronized with the rotational rate of the cylindrical film and with the effective angular displacement rate between the mask and the axis of the cylindrical film.