Method for evaluating the performance of detectors in a computed tomography system
AssigneeGeneral Electric Company
InventorJiang Hsieh
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Abstract
An x-ray CT scanner is operated in a test mode to acquire attenuation projections using a phantom shaped to accentuate errors due to non-uniform detector response along the z-axis. Error values are calculated for detector elements and these error values are compared with preset limits to identify faulty or marginal detector elements.
Claims5
A method for identifying deteriorated detector elements in a computed tomography system having an x-ray source for producing a fan beam of x-rays along a fan beam plane and with a thickness along an axis normal to the fan beam plane, and having a set of detector elements disposed in the fan beam of x-rays to produce a corresponding set of attenuation signals that indicate the x-ray flux density profile of the fan beam, the steps comprising:
- a) acquiring a set of attenuation signals from the detector elements with a reference phantom disposed in the fan beam of x-rays that attenuates the x-rays such that the flux density of the x-rays striking the detector elements has a substantial gradient along the thickness direction;
- b) calculating an error (e) for each of a plurality of detector elements centered about a system iso-center by comparing the value of the detector element attenuation signal with a model curve which represents an ideal x-ray flux density profile of the reference phantom;
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- c) comparing each detector element error (e) with a preset limit and indicating a faulty detector element when the error (e) exceeds the preset limit.
Dependencies are inferred from the claim text.