Effects of x‐ray beam equalization on mammographic imaging

We employed an elastic reservoir filled with tissue-equivalent fluid as an x-ray beam filter for exposure equalization. The filter is designed to be placed between the upper compression plate and the breast. During compression, it will conform to the shape of the peripheral region of the breast and fill the space between the upper and lower compression plates, thereby reducing the variation in x-ray penetration between the thick and thin regions of the breast and compressing the dynamic range of the breast image. Results of a phantom study showed that the visibility of low-contrast features was improved in the peripheral region of the equalized breast phantom image. Experimental measurements indicated that the filter reduced scattered radiation in the peripheral region. This result was confirmed by a Monte Carlo simulation study. The radiation contrast, with the effect of beam hardening included, was also improved when equalization was employed.