US 6,324,246 B1Granted

Helical scanner with variably oriented scan axis

AssigneeMarconi Medical Systems Israel Ltd.

InventorDavid Ruimi

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Abstract

A method for reconstructing images of a subject in a variable-angle helical-scan CT scanner including an X-ray tube, a detector array, and a bed, the method comprising: angling the translation axis and the rotation axis at an acute angle relative to one another; rotating the X-ray tube about the rotation axis while translating the bed along the translation axis through a plane of rotation of the tube, whereby the X-ray tube describes a helical path relative to the subject; acquiring first and second views of the subject at the same effective rotational angle about the axis of rotation, said views comprising X-ray attenuation data received from elements of the array; producing a planar corrected image slice by interpolation of the data in different views, wherein the data is generated by non-corresponding elements in the different views; and repeating the above steps at respective positions at a plurality of rotational angles of the X-ray tube.

Claims23

Dependent claims

A method for reconstructing images of an object in a variable-angle helical-scan CT scanner, said scanner including an X-ray tube mounted for rotation about a rotation axis, a detector array having one or more rows of detector elements that generate signals responsive to X-rays incident thereon, and a surface, translatable along a translation axis, on which surface the object is placed, said method comprising:

(a) angling the translation axis and the rotation axis at an acute angle relative to one another;
(b) rotating the X-ray tube about the rotation axis while translating the surface along the translation axis through a plane of rotation of the tube, whereby the X-ray tube describes a helical path relative to the object;
(c) acquiring first, second and optionally additional views at the same effective rotational angle about the axis of rotation, said views comprising X-ray attenuation data received from elements of the array;
(d) producing a planar corrected view at a given image slice position by interpolation of the data in at said first, second and optionally additional views, wherein the data is generated by non-corresponding elements in different views;
and
(e) repeating (a)-(d) at a plurality of rotational angles of the X-ray tube, for the given slice position;
and
(f) reconstructing an image of the slice from planar corrected views taken over a given range of view angles;
wherein images taken at angle separated by integral multiples of 180 or 360 degrees, depending on the range of view angles, are defined as being taken at the same effective angle.

6 more elements

(a) angling the translation axis and the rotation axis at an acute angle relative to one another;
(b) rotating the X-ray tube about the rotation axis while translating the surface along the translation axis through a plane of rotation of the tube, whereby the X-ray tube describes a helical path relative to the object;
(c) acquiring first, second and optionally additional views of the object at the same effective rotational angle about the axis of rotation, said views comprising X-ray attenuation data received from elements of the array;
(d) producing a planar corrected view at a given image slice position by interpolation of the data in said first, second and optionally additional views;
and
(e) repeating (a)-(d) at a plurality of rotational angles of the X-ray tube for the given slice position;
and
(f) reconstructing an image of the slice from planar corrected views taken over a given range of view angles;
and
wherein images taken at angle separated by integral multiples of 180 or 360 degrees, depending on the range of view angles, are defined as being taken at the same effective angle,
wherein determining a value for interpolation at a point in the view comprises finding the two elements in a row whose centroids are closest to the point and calculating an effective row element attenuation value based on signals received from the two elements.

8 more elements

Dependencies are inferred from the claim text.