| 摘要 |
PROBLEM TO BE SOLVED: To appropriately extract a specific structure by eliminating unneces sary structures when performing energy subtraction on a radiograph image. SOLUTION: The relation between a difference in logarithmic dose (logarithmic dose difference) at every picture element on sheets IP1, IP2, and IP3 and the mean attenuation coefficient on each sheet is stored in advance in a storing means 20 as a table T. A subtraction means 18 performs energy subtraction by finding the mean attenuation coefficient on each sheet from the logarithmic dose difference by referring to the table T and setting the weighting factor on each sheet as the weighting factor for use in performing the energy subtraction by calculating the weighted mean of the mean attenuation factor on each sheet by using a coefficient found based on the standard deviation of the mean attenuation coefficient. |
