Patent ID: 6968030

Claim:
A CT system comprising: a rotatable gantry having an opening to receive a subject to be scanned; a movable high frequency electromagnetic energy projection source configured to project a high frequency electromagnetic energy beam toward the subject at at least two view angles; a movable pre-subject collimator having a bowtie filter that is rotatable about itself relative to an axis of rotation extending through the filter and generally perpendicular to the energy beam during an imaging session, the bowtie filter designed to reduce high frequency electromagnetic energy dosage to the subject as a function of projection source view angle and having multiple filtering profiles; a scintillator array having a plurality of scintillator cells wherein each cell is configured to detect high frequency electromagnetic energy passing through the subject; a photodiode array optically coupled to the scintillator array and comprising a plurality of photodiodes configured to detect light output from a corresponding scintillator cell; a data acquisition system (DAS) connected to the photodiode array and configured to receive the photodiode outputs; an image reconstructor connected to the DAS and configured to reconstruct an image of the subject from the photodiode outputs received by the DAS; and a computer programmed to rotate the filter about the axis of rotation such that at a first view angle a first filtering profile filters the high frequency electromagnetic energy beam and at a second view angle a second filtering profile filters the high frequency electromagnetic energy beam.