An X-ray CT system is equipped with a gantry, couch and control cabinet and configured
to scan a cone-beam X-ray toward an object along a given orbit to acquire cone-beam
data in which a three-dimensional distribution of an X-ray absorption coefficient
within the object is reflected. The control cabinet decides a degree of reliability
for the cone-beam data according to an acquisition time of the cone-beam data,
and then decides a weight for three-dimensional Radon data from the cone-beam data
on the basis of the degree of reliability. Using this weight, the control cabinet
reconstructs the three-dimensional Radon data based on a three-dimensional reconstruction
algorithm. Thus, when the three-dimensional reconstruction algorithm for cone-beam
CT is applied to medical CT, artifacts attributable to object's motion can be suppressed
and temporal resolution can be improved.
