A comparison of mammographic x-ray spectra

X-ray spectra produced by mammographic systems are compared to spectra from conventional diagnostic x-ray systems. Some systems use special anode materials and beam filters to produce x-ray spectra more suitable for mammography. The data show that the spectra produced by some systems are unique; in fact, one using molybdenum for both an anode and beam filtering element can produce an x-ray spectrum having more than 80% of the photons below 20 KeV. Using some typical breast phantom materials as attenuators, the primary x-ray spectra incident upon the imaging system were simulated and displayed. Implications of spectral shaping to image quality and patient dose are discussed.