Patent ID: 7688936

Claim:
A CT system comprising: a rotatable gantry having an opening for receiving a subject to be scanned; an HF electromagnetic energy source configured to project a number of HF electromagnetic energy beams toward the subject; a generator configured to energize the HF electromagnetic energy source to at least a first energy state and a second energy state; a first filtering apparatus comprising a number of HF electromagnetic energy filters positional between the HF electromagnetic energy source and the subject, the number of HF electromagnetic energy filters including at least a first filter and a second filter wherein the first filter is positioned between the HF electromagnetic energy source and the subject by rotation of the first filtering apparatus before the HF electromagnetic energy source is energized to the first energy state and the second filter is positioned between the HF electromagnetic energy source and the subject by rotation of the first filtering apparatus before the HF electromagnetic energy source is energized to the second energy state; and wherein a plane of the first filter through which the HF electromagnetic energy beams pass when the source is energized to the first energy state is parallel with an axis of rotation of the first filtering apparatus, and a plane of the second filter through which the HF electromagnetic energy beams pass when the source is energized to the second energy state is parallel with the axis of rotation of the axis of rotation of the first filtering apparatus.