Dynamic filter for computed tomography (CT)
AssigneeKoninklijke Philips N.V.
InventorRoland Proksa
Life of this patent
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Abstract
An imaging system including a source (310) having a focal spot (406) that emits a radiation beam that traverses an examination region, a radiation sensitive detector array (316) having a plurality of pixels that detects radiation traversing the examination region and generates projection data indicative of the detected radiation, and a filter (314), disposed between the source and the examination region, that filters peripheral regions of the emitted radiation, wherein the filter includes two separate and moveable regions (402), each region having a substantially same thickness and constant homogeneity.
Claims13
An imaging system, comprising:
- a source having a focal spot that emits an x-ray radiation beam collimated by collimator that traverses an examination region;
- a radiation sensitive detector array having a plurality of pixels that detects radiation traversing the examination region and generates projection data indicative of the detected radiation;
- a filter, disposed between the source with the collimator and the examination region, that filters peripheral regions of the emitted x-ray radiation, wherein the filter includes two separate and moveable regions, each region having a substantially same thickness and constant homogeneity,
- wherein each of the filter regions is configured to move along an arc shaped path about the focal spot, which changes an attenuation profile of the filter;
- wherein each of the filter regions is configured to dynamically move in accordance with a shape of an object or subject during scanning of the object or subject, and wherein the shape of the object or subject is determined based on one or more pre-scans of the object or subject;
- and
- a reconstructor that calibrates a detector pixel receiving partially filtered radiation using a hybrid calibration algorithm by detecting a same ray of the x-ray radiation beam from two opposing different directions, wherein a measurement from one of the directions includes partially filtered and partially unfiltered radiation, and a measurement from the other direction includes either fully filtered or fully unfiltered radiation;
- and replacing the measurement corresponding to the partially filtered and partially unfiltered radiation with the measurement corresponding to the fully filtered or fully unfiltered radiation.
A method, comprising:
- filtering peripheral rays, of an emitted x-ray radiation beam collimated by a collimator traversing an examination region, which substantially do not traverse an object or subject in the examination region, with a dynamically adjustable filter having a substantially same thickness and homogeneity along the filter;
- and
- calibrating a detector pixel receiving partially filtered radiation using a hybrid calibration algorithm by:
- detecting a same ray of the x-ray radiation beam from two opposing different directions, wherein a measurement from one of the directions includes partially filtered and partially unfiltered radiation, and a measurement from the other direction includes either fully filtered or fully unfiltered radiation;
- and
- replacing the measurement corresponding to the partially filtered and partially unfiltered radiation with the measurement corresponding to the fully filtered or fully unfiltered radiation.
Dependencies are inferred from the claim text.