US5559847A — Systems, methods and apparatus for reconstructing…

Claim 1

Independent Claim 125 words

A system for producing a tomographic image of an object from projection data acquired in a helical scan, said system including a four row detector array, said tomographic image system comprising an image reconstructor system configured to: (a) create projection data arrays corresponding to the data obtained from each of the x-ray fan beams; (b) apply a weighting function to each of the projection data arrays generated in step (a) to generate respective weighted projection data arrays, the weighting function to be applied for each data set, denoted as W1(β,γ), W2(β,γ), W3(β,γ) and W4(β,γ), being: ##EQU6## where: α(β,γ)=α[x(β,γ)]=3x.sup.2 (β,γ)-2x.sup.3 (β,γ), and where: ##EQU7## (c) from the projection data arrays generated in step (b), generate image data arrays to be used to construct a slice image.

Claim 2

Independent Claim 125 words

A system for producing a tomographic image of an object from projection data acquired in a helical scan, said system including a four row detector array, said tomographic image system comprising an image reconstructor system configured to: (a) create projection data arrays corresponding to the data obtained from each of the x-ray fan beams; (b) apply a weighting function to each of the projection data arrays generated in step (a) to generate respective weighted projection data arrays, the weighting function to be applied for each data set, denoted as W1(β,γ), W2(β,γ), W3(β,γ) and W4(β,γ), being: ##EQU6## where: α(β,γ)=α[x(β,γ)]=3x.sup.2 (β,γ)-2x.sup.3 (β,γ), and where: ##EQU7## (c) from the projection data arrays generated in step (b), generate image data arrays to be used to construct a slice image.

Claim 3

Dependent Claim 27 words

A system in accordance with claim 1 wherein generating image data arrays comprises the step of performing filtration and back projection on each weighted projection data array.

Claim 4

Dependent Claim 29 words

A system in accordance with claim 2 wherein prior to performing filtration and back projection, data arrays from a same gantry angle but from different detector rows are combined.

Claim 5

Dependent Claim 42 words

A system in accordance with claim 3 wherein if a projection view in a first data row are three hundred and sixty degrees from the a projection view in a fourth data row, combining the views prior to filtration and back projection.

Claim 6

Dependent Claim 33 words

A system in accordance with claim 1 wherein prior to applying a weighting function to each of the projection data arrays, the data are stored in a system memory for reconstructing consecutive slices.

Claim 7

Dependent Claim 41 words

A system in accordance with claim 1 wherein said image reconstructor system is further configured to sum multiple thin slices within a desired slice profile if the desired slice profile is thicker than the thinnest profile supported by the data array.

Claim 8

Independent Claim 118 words

A method for producing a tomographic image of an object from projection data acquired from a four row detector array in a helical scan, said method comprising the steps of: (a) creating projection data arrays corresponding to the data obtained from each of the x-ray fan beams; (b) applying a weighting function to each of the projection data arrays generated in step (a) to generate respective weighted projection data arrays, the weighting factors to be applied for each data set, denoted as W1(β,γ), W2(β,γ), W3(β,γ) and W4(β,γ), being: ##EQU8## where: α(β,γ)=α[x(β,γ)]=3x.sup.2 (β,γ)-2x.sup.3 (β,γ) and where: ##EQU9## (c) from the projection data arrays generated in step (b), generating image data arrays to be used to construct a slice image.

Claim 9

Independent Claim 118 words

A method for producing a tomographic image of an object from projection data acquired from a four row detector array in a helical scan, said method comprising the steps of: (a) creating projection data arrays corresponding to the data obtained from each of the x-ray fan beams; (b) applying a weighting function to each of the projection data arrays generated in step (a) to generate respective weighted projection data arrays, the weighting factors to be applied for each data set, denoted as W1(β,γ), W2(β,γ), W3(β,γ) and W4(β,γ), being: ##EQU8## where: α(β,γ)=α[x(β,γ)]=3x.sup.2 (β,γ)-2x.sup.3 (β,γ) and where: ##EQU9## (c) from the projection data arrays generated in step (b), generating image data arrays to be used to construct a slice image.

Claim 10

Dependent Claim 25 words

A method with claim 7 wherein generating image data arrays comprises the step of performing filtration and back projection on each weighted projection data array.

Claim 11

Dependent Claim 31 words

A method in accordance with claim 8 wherein prior to performing filtration and back projection, and the data arrays from a same gantry angle but from different detector rows are combined.

Claim 12

Dependent Claim 43 words

A method in accordance with claim 9 wherein if a projection view in a first data row are three hundred and sixty degrees from the a projection view in a fourth data row, combining the view prior to performing filtration and back projection.

Claim 13

Dependent Claim 32 words

A method in accordance with claim 8 wherein prior to applying a weighting function to each of the projection data arrays, storing the data in a system memory for reconstructing consecutive slices.

Claim 14

Dependent Claim 34 words

A method in accordance with claim 8 wherein multiple thin slices within a desired slice profile are summed if the desired slice profile is thicker than the thinnest profile supported by the data array.

Claim 15

Dependent Claim 83 words

A volumetric computed tomography apparatus, comprising: (a) a gantry having an x-ray source and a multi-row detector; (b) a data acquisition system coupled to said detector; and (c) a processor coupled to said data acquisition system, said processor configured to estimate, for a location z 0 , projection data P z0 (β,γ) using projection data measured by said detector rows at locations z 1 and z 2 , said processor programmed to estimate the projection data P z0 (β,γ) using the relationship: ##EQU10##

Claim 16

Dependent Claim 83 words

A volumetric computed tomography apparatus, comprising: (a) a gantry having an x-ray source and a multi-row detector; (b) a data acquisition system coupled to said detector; and (c) a processor coupled to said data acquisition system, said processor configured to estimate, for a location z 0 , projection data P z0 (β,γ) using projection data measured by said detector rows at locations z 1 and z 2 , said processor programmed to estimate the projection data P z0 (β,γ) using the relationship: ##EQU10##

Claim 17

Dependent Claim 24 words

A volumetric computed tomography apparatus in accordance with claim 13 wherein detectors in different rows contribute to the estimated projection data P z0 (β,γ).

Claim 18

Dependent Claim 36 words

A volumetric computed tomography apparatus in accordance with claim 13 further comprising an image reconstructor, said reconstructor being configured to generate an image slice at location z 0 utilizing the estimated projection data P z0 (β,γ).

Claim 19

Dependent Claim 83 words

A volumetric computed tomography apparatus, comprising: (a) a gantry having an x-ray source and a multi-row detector; (b) a data acquisition system coupled to said detector; and (c) a processor coupled to said data acquisition system, said processor configured to estimate, for a location z 0 , projection data P z0 (β,γ) using projection data measured by said detector rows at locations z 1 and z 2 , said processor programmed to estimate the projection data P z0 (β,γ) using the relationship: ##EQU11##

Claim 20

Dependent Claim 83 words

A volumetric computed tomography apparatus, comprising: (a) a gantry having an x-ray source and a multi-row detector; (b) a data acquisition system coupled to said detector; and (c) a processor coupled to said data acquisition system, said processor configured to estimate, for a location z 0 , projection data P z0 (β,γ) using projection data measured by said detector rows at locations z 1 and z 2 , said processor programmed to estimate the projection data P z0 (β,γ) using the relationship: ##EQU11##

Claim 21

Dependent Claim 24 words

A volumetric computed tomography apparatus in accordance with claim 16 wherein detectors in different rows contribute to the estimated projection data P z0 (β,γ).

Claim 22

Dependent Claim 36 words

A volumetric computed tomography apparatus in accordance with claim 16 further comprising an image reconstructor, said reconstructor being configured to generate an image slice at location z 0 utilizing the estimated projection data P z0 (β,γ).

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-09-24	2000-03-25	2000-09-24	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-09-24	2004-03-25	2004-09-24	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-09-24	2008-03-25	2008-09-24	$7700.00	Window Closed / Lapsed

Systems, methods and apparatus for reconstructing images in a CT system implementing a helical scan

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