| 摘要 |
For each of at least three types of X-ray radiation with different average energies, the average intensity I0 (En, X, Y) of a background region of an object and the intensity I (En, X, Y) of each pixel in a transmission image of X-rays transmitted through the same region of the object are obtained. For each average energy, the measured absorption coefficient μ of the object is determined by dividing each intensity I (En, X, Y) by the average intensity I0 (En, X, Y) at the same average energy, and calculating the minus natural logarithm (-ln(x)). One of the at least three types of X-ray radiation is set as a standard energy E0, and a relative measured absorption coefficient μ' is calculated by dividing, by the measured absorption coefficient μ corresponding to the standard energy E0, a measured absorption coefficient μ corresponding to another average energy. Then, the theoretical composite absorption coefficient μIc of each expected element is calculated for each average energy on the basis of the theoretical absorption coefficient μI and content σi of the element. The content σi with which the sum of squares of the differences from the relative measured absorption coefficients μ' calculated for each average energy is smallest is calculated by repeated computation. |
