Variable dose application by modulation of x-ray tube current during CT scanning
First Claim
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1. A method for reducing the dose of an x-ray beam applied to a patient by an x-ray CT system during the acquisition of attenuation data from a single slice as a gantry rotates around the patient, the steps comprising:
- acquiring patient projection data from the slice which indicates patient attenuation of the x-ray beam at two substantially orthogonal gantry angles;
calculating a modulation profile using information derived from the acquired patient projection data, the modulation profile indicating the x-ray dose to be applied to the patient as a function of gantry angle; and
acquiring the attenuation data for the single slice by rotating the gantry around the patient and modulating the applied x-ray dose as indicated by the modulation profile.
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Abstract
An x-ray CT system modulates x-ray tube current as a function of gantry angle to reduce the total patient dose without significantly increasing image noise. A scout scan is performed to acquire attenuation data which enables an optimal current modulation profile to be calculated for each slice in the scan.
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9 Claims
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1. A method for reducing the dose of an x-ray beam applied to a patient by an x-ray CT system during the acquisition of attenuation data from a single slice as a gantry rotates around the patient, the steps comprising:
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acquiring patient projection data from the slice which indicates patient attenuation of the x-ray beam at two substantially orthogonal gantry angles; calculating a modulation profile using information derived from the acquired patient projection data, the modulation profile indicating the x-ray dose to be applied to the patient as a function of gantry angle; and acquiring the attenuation data for the single slice by rotating the gantry around the patient and modulating the applied x-ray dose as indicated by the modulation profile. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for reducing the dose of an x-ray beam applied to a patient by an x-ray CT system during the acquisition of attenuation data from a single slice, the steps comprising:
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storing a modulation profile which indicates variations in x-ray beam intensity as a function of gantry angle during the acquisition of attenuation data; modulating an x-ray tube operating parameter using values stored in the modulation profile; and acquiring a slice of attenuation data while the x-ray tube operating parameter is modulated. - View Dependent Claims (8, 9)
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Specification