Computerized tomographic imaging method and apparatus utilizing data interpolation for helical scanning

Claim 1

An X-ray computerized tomographic imaging apparatus (100) for reconstructing tomographic images of multi-planer slices of an object under medical examination, comprising: table couch means (2) for supporting the object (M) under medical examination; table couch drive control means (8) for controlling a continuous transportation of the table couch means (2) along a longitudinal axis of the object (M); an X-ray beam source (3) for radiating a fan-shaped X-ray beam toward the multi-planer slices of the object (M); detector means (4) for detecting the fan-shaped X-ray beam which has penetrated through the slices of the objects (M) to thereby produce projection data representative of profile intensities of the fan-shaped X-ray beam; means (1) for mounting both the X-ray beam source (3) and the detector means (4) in such a manner that the X-ray beam source (3) is continuously positioned opposite to the detector means (4) with respect to the slice of the object (M), while detecting the fan-shaped radiation beam, and for performing a relative movement between the X-ray beam source (3) and the object (M) in a plane which is perpendicular to the longitudinal axis of the object (M), whereby a helical scanning around the object (M) is realized by the continuous transportation of the table couch means (2) and the relative movement between them; and, interpolation calculating means (10) for obtaining slice projection data at a predetermined slice point (C₁:C₂) on a slice plane (SC) by performing an interpolation calculation based upon at least one pair of first actually-acquired projection data at a first point (D₁:E₂) which is located nearest the slice point (C₁:C₂) and has the same rotation phase relationship with the slice point (C₁:C₂) during the helical scanning, and also second actually-acquired projection data at a second point (E₁:D₂) located opposite to the first point (D₁:E₂) as a center of the slice plane (SC), whereby said tomographic image of the object (M) at the slice plane is reconstructed based upon at least a plurality of interpolated slice projection data.

Claim 5

A method for reconstructing tomographic images of multi-planer slices of an object under medical examination in an X-ray computerized tomographic imaging apparatus (100), comprising the steps of: radiating the object (M) under medical examination by a fan-shaped X-ray beam, while continuously translating the object (M) along a longitudinal axis thereof and relatively rotating an X-ray radiating source (3) and a detector (4) for detecting the fan-shaped X-ray beam penetrated through the object to produce projection data representative of profile intensities of the fan-shaped X-ray beam, whereby a helical scanning around the object (M) is realized by the continuous transportation of the object (M); executing an interpolation calculation so as to obtain slice projection data at a predetermined slice (C₁:C₂) on a slice plane (SC) by utilizing at least one pair of first actually-acquired projection data at a first point (D₁:E₂) which is located nearest the slice point (C₁:C₂) and has the same rotation phase relationship with the slice point (C₁:C₂) during the helical scanning, and also second actually-acquired projection data at a second point (E₁:D₂) located opposite to the first point (D₁:E₂) as a center of the slice plane (SC), whereby said tomographic image of the object (M) at the slice plane is reconstructed based upon at least a plurality of interpolated slice projection data.