Apparatus and method for therapeutically irradiating a chosen area using a diagnostic computer tomography scanner

This patent describes a diagnostic computer tomography scanner that uses a radiant energy beam for imaging purposes, an apparatus for therapeutically irradiating a chosen area with the radiant energy beam. It comprises: a masking member fabricated from a material that partially attenuates the radiant energy passing therethrough, but transmits a sufficient amount of the radiant energy for imaging purposes and having an aperture therein adapted for passing an unattenuated portion of the radiant energy beam therethrough; means for fastening the masking member to the scanner interposing the masking member in the radiant energy beam intermediate the source of the radiant energy beam and the chosen area for passing the unattenuated portion of the radiant energy beam to irradiate the chose area; means for selectively varying the cross-sectional shape of the masking member aperture in a predetermined manner as a function of the location of the chosen area and the position of the source of the radiant energy beam; means for selectively varying the spatial position of the masking member aperture in a predetermined manner as a function of the location of the chosen area and the position of the source of the radiant energy beam; and, a post-masking member aligned with the masking aperture and fabricated of a material that attenuates the radiant energy passing therethrough to an energy level essentially uniform with that of the radiant energy passing through the masking member