Dynamic dose control in multi-slice CT scan
First Claim
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1. A method for adjusting the dose of an x-ray beam applied to a patient by an x-ray CT system during a multi-slice acquisition of attenuation data, the steps comprising:
- acquiring patient projection data from each slice which indicates patient attenuation of the x-ray beam;
calculating a relative attenuation function RAF(z) from the acquired patient projection data which indicates the expected x-ray beam attenuation at each slice location relative to the x-ray beam attenuation of a known reference object;
calculating an x-ray tube current command mA(z) for each slice using the corresponding value of the relative attenuation function RAF(z) and a reference x-ray tube current command mAref which produces the desired x-ray dose in the known reference object; and
acquiring each slice of attenuation data with an x-ray dose determined by the x-ray tube current command mA(z) for that slice.
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Abstract
An x-ray CT system performs a multi-slice scan in which tube current is modulated to reduce the x-ray dose without increasing image noise. Scout data is acquired from which a relative attenuation function (RAF) is calculated to relate expected patient attenuation of the x-ray beam at each slice to a reference. Tube current commands (mA) for each slice are calculated from the RAF and used to acquire image data.
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Citations
8 Claims
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1. A method for adjusting the dose of an x-ray beam applied to a patient by an x-ray CT system during a multi-slice acquisition of attenuation data, the steps comprising:
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acquiring patient projection data from each slice which indicates patient attenuation of the x-ray beam; calculating a relative attenuation function RAF(z) from the acquired patient projection data which indicates the expected x-ray beam attenuation at each slice location relative to the x-ray beam attenuation of a known reference object; calculating an x-ray tube current command mA(z) for each slice using the corresponding value of the relative attenuation function RAF(z) and a reference x-ray tube current command mAref which produces the desired x-ray dose in the known reference object; and acquiring each slice of attenuation data with an x-ray dose determined by the x-ray tube current command mA(z) for that slice. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification