Patent ID: 8494111

Claim:
A computed-tomography apparatus, comprising: an x-ray source; an x-ray detector disposed to receive x-rays from said x-ray source; a data collection unit; a processing unit for processing said data using a weighting function given as w CB ⁡ ( β , γ , v ) = u FB ⁡ ( β ) · u CB ⁡ ( v , γ ) ∑ n = - N N ⁢ ( u FB ⁡ ( β n ⁡ ( β , γ ) ) · u CB ⁡ ( v n ) ) where β is a projection angle of said x-rays, γ is a fan angle of said x-rays, N is a number of helical half-turns, n is an index of complementary rays and ν is a detector coordinate parallel to axis of rotation of said x-ray source, and wherein said processing uses said weighting function where: u CB ⁡ ( v , γ ) = { 0 , v < v - ⁡ ( γ ) - δ ⁢ ⁢ v - ⁡ ( γ ) p ⁡ ( v - v - ⁡ ( γ ) + δ ⁢ ⁢ v - ⁡ ( γ ) 2 ⁢ δ ⁢ ⁢ v - ⁡ ( γ ) ) , v - ⁡ ( γ ) - δ ⁢ ⁢ v - ⁡ ( γ ) ≤ v < - v - ⁡ ( γ ) + δ ⁢ ⁢ v - ⁡ ( γ ) 1 , v - ⁡ ( γ ) + δ ⁢ ⁢ v - ⁡ ( γ ) ≤ v ≤ v + ⁡ ( γ ) - δ ⁢ ⁢ v + ⁡ ( γ ) p ⁡ ( v + ⁡ ( γ ) + δ ⁢ ⁢ v + ⁡ ( γ ) - v 2 ⁢ δ ⁢ ⁢ v + ⁡ ( γ ) ) , v + ⁡ ( γ ) - δ ⁢ ⁢ v + ⁡ ( γ ) < v ≤ v + ⁡ ( γ ) + δ ⁢ ⁢ v + ⁡ ( γ ) 0 , v > v + ⁡ ( γ ) + δ ⁢ ⁢ v + ⁡ ( γ ) where ν + (γ) and ν − (γ) are boundaries of an n-PI window and δν + (γ) and δν − (γ) are smoothing intervals.