Partial scan weighting for multislice CT imaging with arbitrary pitch
AssigneeGE Medical Systems Global Technology Company, LLC
InventorGuy M. Besson
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Abstract
A method is provided for reconstructing an image from a set of projection data acquired in a computed tomgraphic (CT) scan of an object. The method includes selecting a pitch in a range between a zero pitch and a high-speed (HS) pitch, helically scanning the object with a CT imaging system having a multislice detector and a moving radiation source, at the selected pitch, to acquire projection data, and helically interpolating the acquired projection data to generate or synthesize projections in a plane of reconstruction for a source angle β spanning a partial scan angle. The method also includes applying a partial scan weight WPS to the generated or synthesized projections in a plane of reconstruction, and filtering and backprojecting the weighted projections.
Claims24
A method for reconstructing an image from a set of projection data acquired in a computed tomographic (CT) scan of an object, comprising the steps of:
- selecting a pitch in a range between a zero pitch and an HS pitch;
- helically scanning the object with a CT imaging system having a multislice detector and a moving radiation source, at the selected pitch, to acquire projection data;
- helically interpolating the acquired projection data to generate or synthesize projections in a plane of reconstruction for a source angle β spanning a partial scan angle;
- applying a partial scan weight WPS written as:
- W PS ( β , γ ) = β - π 2 + Γ 2 ( Γ - γ ) β inf = π 2 - Γ ≤ β ≤ β - = π 2 + Γ - 2 γ W PS ( β , γ ) = 1.0 β - ≤ β ≤ β + = 3 π 2 - Γ - 2 γ W PS ( β , γ ) = 3 π 2 + Γ - β 2 ( Γ + γ ) β + ≤ β ≤ β sup = 3 π 2 + Γ ( 1 )
- to the generated or synthesized projections in a plane of reconstruction, where γ is a fan angle, β a source angle, and Γ a maximum fan angle;
- and
- filtering and backprojecting the weighted projections.
A computed tomography (CT) imaging system having a multislice detector and a moving radiation source, said imaging system configured to:
- select a pitch in a range between a zero pitch and an HS pitch;
- helically scan an object with a CT imaging system having a multislice detector and a moving radiation source, at the selected pitch, to acquire projection data;
- helically interpolate the acquired projection data to generate or synthesize projections in a plane of reconstruction for a source angle β spanning a partial scan angle;
- apply a partial scan weight WPS written as:
- W PS ( β , γ ) = β - π 2 + Γ 2 ( Γ - γ ) β inf = π 2 - Γ ≤ β ≤ β - = π 2 + Γ - 2 γ W PS ( β , γ ) = 1.0 β - ≤ β ≤ β + = 3 π 2 - Γ - 2 γ W PS ( β , γ ) = 3 π 2 + Γ - β 2 ( Γ + γ ) β + ≤ β ≤ β sup = 3 π 2 + Γ ( 1 )
- to the generated or synthesized projections in a plane of reconstruction, where γ is a fan angle, β a source angle, and Γ a maximum fan angle;
- and
- filter and backprojecting the weighted projections.
Dependencies are inferred from the claim text.