Transfer Functions For Xeroradiographs And Electronic Image Enhancement Systems

Xeroradiography has been felt by many radiologists to be diagnostically superior to no-screen x-ray films for mammography. Recently we have shown that Xeroradiography has a modulation transfer function similar to that of "soft focus masking" or "dodging" wherein low spatial frequencies are reduced almost to zero while frequencies near one line pair per millimeter are greatly accentuated. Since lower spatial frequencies contain information mostly about the size and shape of the breast while the higher ones presumably contain diagnostic information about small calcifications and blood vessel structure, it would appear that Xeroradio-graphy is able to present the spatial frequencies of interest with great contrast without exceeding the dynamic range of the powdered image in large sections.