| 摘要 |
PROBLEM TO BE SOLVED: To certainly put the projection data by the X-ray beam near to the reconstruction surface in the projection data collected by helical scanning to practical use when reconstructing a CT image. SOLUTION: The weighting coefficient to be subjected to the multiplication of the projection data s(α<SB>d</SB>i,β<SB>d</SB>i,γ<SB>d</SB>i) and s(α<SB>c</SB>i,β<SB>c</SB>i,γ<SB>c</SB>i), wherein corresponding X-ray beams pass through the pixels P on the reconstruction surface RP in the reconstruction algorithm of pixel data and the view angle directions thereof are opposed to each other, is calculated according to a numerical formula using a term of the distanceΔZ between an X-ray data collecting system 41 when collecting the projection data and the reconstruction surface RP + an offset distanceΔZ<SB>offset</SB>. For example, the projection data s(α<SB>d</SB>i,β<SB>d</SB>i,γ<SB>d</SB>i) is multiplied by the weighting coefficient. Herein, the weighting coefficient is weighting coefficientω<SB>d</SB>i=(ΔZ<SB>c</SB>i+ΔZ<SB>offset</SB>)/[(ΔZ<SB>d</SB>i+ΔZ<SB>offset</SB>)+(ΔZ<SB>c</SB>i+ΔZ<SB>offset</SB>)] (wherein both ofΔZ<SB>d</SB>i andΔZ<SB>c</SB>i take a minute value and, even if the ratio ofΔZ<SB>d</SB>i andΔZ<SB>c</SB>i is largely biased, a state becoming extremely small in one weighting coefficient is prevented by the presence ofΔZ<SB>offset</SB>). COPYRIGHT: (C)2010,JPO&INPIT |
