Method and apparatus of modulating the filtering of radiation during radiographic imaging
AssigneeGeneral Electric Company
InventorsThomas Toth, Tsur Bernstein
Life of this patent
Estimating the term…
Abstract
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.
Claims18
1-27. (Canceled)
A pre-subject filter for a radiographic imaging system, the filter comprising:
- a first end having a first attenuation profile;
- a second end having a second attenuation profile, the second attenuation profile being larger than the first attenuation profile;
- and
- a concave body connecting the first end and the second end, the concave body defining a continuum of attenuating material that varies from the first end to the second end.
The filter of claim 1 wherein the first end further includes a filtering width narrower than a filtering width of the second end.
The filter of claim 1 wherein the concave body has an attenuation profile such that the attenuation power decreases continuously from the first end to the second end.
The filter of claim 1 having a U-shaped cross-section.
The filter of claim 1 wherein the continuum of attenuating material varies linearly from the first end to the second end.
A method of diagnostic imaging comprising the steps of:
- positioning a subject to be scanned into a scanning bay;
- projecting a radiation beam along a beam path toward the subject;
- positioning a filter in the beam path, the filter having variable attenuation parallel to a subject's long axis;
- translating the filter parallel to the subject's long axis to reduce radiation exposure to sensitive anatomical regions of the subject;
- acquiring imaging data of the subject;
- and
- reconstructing an image of the subject from the imaging data.
The method of claim 12 wherein the filter includes:
- a first end having a first attenuation profile;
- a second end having a second attenuation profile, the second attenuation profile being greater than the first attenuation profile;
- and
- a body connecting the first end and the second end.
The method of claim 13 wherein the first end has a filtering width narrower than a filtering width of the second end.
The method of claim 13 wherein the body has a variable attenuation profile that varies continuously along a length of the body from the first end to the second end.
The method of claim 13 wherein the body has a width that tapers from the second end to the first end.
The method of claim 16 wherein the attenuation profile of the body varies non-linearly across any given constant width of the body.
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 rotatable filters formed of attenuating matter;
- 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.
The radiographic imaging system of claim 18 wherein each cam filter has a length and an attenuation profile that varies as a function of filter length
The radiographic imaging system of claim 19 wherein the attenuation profile of each filter is a function of filter thickness.
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 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.
The cam filter assembly of claim 25 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.
The cam filter assembly of claim 25 wherein each filter has a generally rod-shaped body.
Dependencies are inferred from the claim text.