X-ray CT device and method for correcting scattered X-rays

An X-ray CT scanner comprising:

• a scanning section that scans an object to obtain X-ray transmission image data of the object from a plurality of projection directions, the scanning section comprising an X-ray source generating X-rays from an X-ray focus and an X-ray detector having X-ray detection elements in a two-dimensional array so as to detect the X-rays, wherein the X-ray source and the X-ray detector rotate around the object while facing each other and the object is interposed therebetween;
• an internal-distribution-estimating section that estimates an X-ray absorption coefficient distribution inside the object, based on the X-ray transmission image data scanned by the scanning section;
• an X-ray-distribution-estimating section that estimates a distribution of scattered X rays derived from the object by performing a Monte Carlo simulation to simulate a physical interaction of the X-rays in a simulated object having the X-ray absorption coefficient distribution estimated by the internal-distribution-estimating section;
• a correction section that removes components of the scattered X-rays from the X-ray transmission image data, based on the distribution estimated by the X-ray-distribution-estimating section;
• and
• an image-creating section that creates an image of the X-ray absorption coefficient distribution of the object by using the X-ray transmission image data in which the components of the scattered X-rays have been removed by the correction section.

A method for scatter correction, comprising:

• a scanning step of scanning an object to obtain X-ray transmission image data of the object from a plurality of projection directions, a scanning section including an X-ray source generating X-rays from an X-ray focus and an X-ray detector having X-ray detection elements in a two-dimensional array so as to detect the X-rays, wherein the X-ray source and the X-ray detector rotate around the object while facing each other and the object is interposed therebetween;
• an internal-distribution-estimating step of estimating an X-ray absorption coefficient distribution inside the object, based on the X-ray transmission image data scanned in the scanning step;
• a point-spread-function-estimating step of estimating a point spread function of a scatter derived from the object by performing a Monte Carlo simulation to simulate a physical interaction of the X-rays in a simulated object having the X-ray absorption coefficient distribution estimated in the internal-distribution-estimating step;
• a correction step of correcting the X-ray transmission image data by processing the point spread function estimated in the point-spread-function-estimating step and the X-ray transmission image date according to a deconvolution integral method;
• and
• an image-creating step of creating an image of the X-ray absorption coefficient distribution of the object by using the X-ray transmission image data corrected in the correction step.

A method for scatter correction, comprising:

• a scanning step of scanning an object to obtain X-ray transmission image data of the object from a plurality of projection directions, a scanning section including an X-ray source generating X-rays from an X-ray focus and an X-ray detector having X-ray detection elements in a two-dimensional array so as to detect the X-rays, wherein the X-ray source and the X-ray detector rotate around the object while facing each other and the object is interposed therebetween;
• an internal-distribution-estimating step of estimating an X-ray absorption coefficient distribution inside the object, based on the X-ray transmission image data scanned in the scanning step;
• an X-ray-distribution-estimating step of estimating a distribution of scattered X rays derived from the object by performing a Monte Carlo simulation to simulate a physical interaction of the X-rays in a simulated object having the X-ray absorption coefficient distribution estimated in the internal-distribution-estimating step;
• a correction step of removing components of the scattered X-rays from the X-ray transmission image data, based on the distribution estimated in the X-ray-distribution-estimating step;
• and
• an image-creating step of creating an image of the X-ray absorption coefficient distribution of the object by using the X-ray transmission image data in which the components of the scattered X-rays have been removed in the correction step.