US 5,625,660 AGranted

Image reconstruction from helical partial cone-beam data

AssigneePicker International, Inc.

InventorHeang K. Tuy

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Abstract

A two-dimensional radiation detector (30) receives divergent ray penetrating radiation along conical or pyramidal ray paths which converge at an apex. The radiation may emanate from one or both of an x-ray tube (16) or radionuclei injected into a human subject. As the radiation detector rotates around the subject, it is repeatedly sampled to generate two-dimensional data sets h.sub.t (u,v) at each of a plurality of samplings t. Each two-dimensional data array is weighted (44) and divided into two components. A first component processor (48) convolves a first component of each two-dimensional array with respect to u for each v. A second component processor (50) processes a second component of each two-dimensional array (FIG. 6) including weighting each component with a geometrically dependent weighting function W from a weighting function computer (46). The processed first and second components are combined (52) and backprojected (54).

Claims15

Dependent claims

A radiographic diagnostic apparatus comprising:

a source of penetrating radiation;
a two-dimensional radiation detector for receiving partial cone-beam radiation along a plurality of divergent rays, the rays being focused at a common origin vertex and diverging in two dimensions;
the radiation detector, the source, and a subject support being disposed to irradiate a subject on the support along at least a helical arc segment of a helical path;
a means for sampling the radiation detector at a plurality of angular increments along the helical arc segment to generate a plurality of two-dimensional views, each view including a two-dimensional array of data values, each data value corresponding to one of the divergent rays, data along rows parallel to a tangent to the helical arc segment at the vertex being untruncated and data in at least one-direction not parallel to the tangent being truncated;
a weighting processor for weighting the data values of each two-dimensional array in accordance with a cosine of an angle between a ray corresponding to the data value and a ray normal to a local coordinate plane at the radiation detector;
a first component processor for convolving a first component of the weighted data values one-dimensionally parallel to the tangent to create a convolved first two-dimensional data component array;
a second component processor for processing a second two-dimensional component array of the weighted data values, the second processor weights each second component value in accordance with characteristics of the helical arc segment and position along the helical arc segment, for taking a partial derivative of the data values of the second component, and for multiplying each data value in accordance with a square of a distance from the vertex of the divergent rays to the radiation detector corresponding to each data value;
an adder for combining the first and second processed components from the first and second component processors;
and,
a backprojector for three-dimensionally backprojecting the sum from the adder into a volumetric image memory.

7 more elements

A method for radiographic diagnostic imaging comprising:

generating penetrating radiation;
receiving the radiation with a two-dimensional radiation detector along a plurality of divergent rays, the rays being focused at a common origin vertex and diverging in two dimensions;
rotating the vertex along at least an arc segment of a helical path;
sampling the radiation detector at a plurality of angular increments along the helical arc segment to generate a plurality of two-dimensional views, each view including a two-dimensional array of data values, each data value corresponding to one of the divergent rays, the data values along rows parallel to a tangent to the arc segment at the vertex being untruncated and the data values in at least one other direction being truncated;
weighting the data values of each two-dimensional array in accordance with a cosine of an angle between a ray corresponding to the data value and a ray normal to a local coordinate plane at the radiation detector;
convolving a first component of the weighted data values one-dimensionally parallel to the tangent to create a convolved first two-dimensional data component array;
processing a second two-dimensional component array of the weighted data, each second component value being weighted in accordance with characteristics of the helical arc segment and position along the helical arc segment, taking a partial derivative of the data values of the second component, and multiplying each data value in accordance with a square of a distance from the vertex of the divergent rays to the radiation detector corresponding to each data value;
combining the first and second processed components;
and,
three-dimensionally backprojecting the sum into a volumetric image memory.

7 more elements

Dependencies are inferred from the claim text.