| 摘要 |
PURPOSE: To reduce a calculation necessary condition for the reproduction of collecting radon data sufficient for reproducing the accurate image of matter irradiated with a scanning cone beam source in uniform distribution. CONSTITUTION: The radon data calculated at the P-point 42 on a projection plane is obtained by the cone beam passing through a line 44 and the line 44 shows the crossing with respect to the segment 45 connecting the P-point 42 and the origin 46. However, the radon data calculated at the P-point 42 corresponds to the data due to the fan-shaped beam source passing through the scanning locus 48 projected on the plane. If the line 44 does not cross the locus 48, the radon data is not generated at the P-point 42. If the line 44 crosses the locus 48 at points more than one, two or more radon data are generated at the P-point 42. Therefore, the density of radon data at the P-point 42 is in direct proportion to the number of times crossing the locus 48 wherein the line 44 is projected on the plane to become a standard of a local signal/noise ratio as a whole. |
