Method and apparatus of modulating the filtering of radiation during radiographic imaging
View Patent ↗The present invention includes a filtering apparatus for a CT imaging system or equivalently for an x-ray imaging system. The filtering apparatus may be translated along a first axis or a transverse axis to with respect to an attenuation pattern of a subject during an imaging session to reduce radiation exposure to anatomical regions of the subject sensitive to radiation exposure and/or regions from which data is not being acquired.
1. A radiographic imaging system comprising:
a scanning bay;
a movable table configured to move a subject to be scanned fore and aft along a first direction within the scanning bay;
an x-ray projection source configured to project x-rays in an x-ray beam toward the subject;
a pair of generally cylindrically-shaped rotatable filters formed of attenuating matter, each filter rotatable about a line of rotation that extends along a long axis of the filter and is defined to be transverse to the x-ray beam; and
a computer programmed to:
determine a region-of-interest of the subject; and
rotate at least one rotatable filter of the pair of rotatable filters such that the pair of rotatable filters limit x-ray exposure outside the region-of-interest.
2. The radiographic imaging system of claim 1 wherein each cam filter has a length and an attenuation profile that varies as a function of filter length.
3. The radiographic imaging system of claim 1 wherein an attenuation profile of each filter is a function of filter thickness.
4. A cam filter assembly for use with a radiation emitting imaging system, the cam filter assembly including a pair of non-overlapping cam filters wherein each cam filter has a generally rod-shaped body and has an attenuation power that varies with thickness of the filter, the pair of cam filters being configured to be independently rotated to collectively manipulate a beam of radiation projected toward a subject to generate a desired radiation profile across a region-of-interest of the subject.
5. The cam filter assembly of claim 4 wherein each filter has a width situated along an x-axis and a length situated along a z-axis, the z-axis being parallel to a long axis of the subject, and wherein each filter has varying attenuation characteristics along its length.