A Numerical Model for Compressed Breast of Japanese Women in Mammography.

The purpose of this study is to develop a numerical model for compressed breast of Japanese women which can evaluate the radiation dose in mammography. The model should take account of the average data for thickness of the compressed breast, and area, height and width of the mammograms. The compressed breast thickness is typically 4.4 to 6.4cm for European and American women, whereas it is under 3.8cm for Japanese women. Therefore, applying the European and American models without any modification for Japanese women would result in an overestimation of the absorbed dose. The data of 560 mammograms were analyzed focusing on the size and geometry of the projected images (cranio-caudal) to formulate a compressed breast phantom. An extremely good linear coefficient of correlation (0.98) between the area and the product of the width and height of the projected images was found. A numerical model describing a part of a simple elliptic column was constructed from this relationship and the averaged thickness (3.15cm) of the compressed breast. This model will lead to a realistic estimation of the total volumetric absorbed dose in mammography.