Patent ID: 7046758

Claim:
An X-ray CT apparatus comprising: an X-ray source for irradiating a fan beam X-ray having a predetermined width; an X-ray detector which is arranged opposite to said X-ray source while sandwiching an object to be examined, and is rotated around said object in combination with said X-ray source under opposite-arranging condition; means for moving, plural times; any one of both said X-ray source and said X-ray detector located opposite to said X-ray source, and a bed on which said object is mounted at a predetermined pitch which is made narrower than an effective X-ray detection width “W” of the X-ray; means for rotating both said X-ray source and said X-ray detector located opposite to said X-ray source so as to execute a CT measurement, and for acquiring a detection signal obtained from said X-ray detector; virtual measurement value calculating means for calculating virtual detection data having a slice width M/N times the effective detection width “W” of the X-ray from said detection signal, while symbols “M” and “N” are integers, are defined by M<N, and are relatively prime; and means for reconstructing a tomographic image from said virtual detection data; wherein a virtual detection data an for a CT measurement value b n for said effective X-ray detection width W is represented as b n ⁢ ∑ i = 0 N - 1 ⁢ ⁢ a ( n * N + i ) ⁢ ⁢ ( n ≥ 0 ) , and a virtual detection data a 0 firstly calculated is obtained from any one of the equation of a 0 =b 0 /N, linear interpolation from an in the vicinity of the a 0 and a condition minimizing the equation of DE=Σ(a n+1 −a n ) 2 .