Patent ID: 7582860

Claim:
A method for measuring an amount of missed tissue at chest wall side, the method comprising the steps of: placing a phantom used for measurement of the amount of missed tissue at chest wall side on a support table for breast radiography, the phantom comprising a reference marker located at a predetermined position in the phantom, a reference surface for positioning, to be placed in contact with a chest wall side of the support table, and a pattern region formed by a region wherein the amount of transmitted radiation used for measurement of a distance from the reference surface shows periodic changes, monotonic decrease or increase, or stepwise changes in a direction perpendicular to the reference surface according to a predetermined rule; recording a radiation image of the phantom in a radiation image conversion panel placed in the support table while radiographing the phantom; obtaining base image data representing a base radiation image of the phantom including the reference marker by performing readout of the radiation image conversion panel; finding a magnification ratio and a position of the phantom from a test radiation image obtained by further radiography of the phantom and from a position of the reference marker recorded in the test radiation image; determining a calculation region corresponding to the pattern region in the test radiation image, based on the position of the phantom and the base image data; finding the number of repetitions and/or the amount of change in the amount of transmitted radiation in the calculation region according to the predetermined rule; and finding the amount of missed tissue at chest wall side from the number of repetitions and/or the amount of the change.