Molybdenum filter optimization in mammography

It is well known that mammographic equipment is generally provided with a molybdenum (Mo) anode and a molybdenum filter tube. The thickness of the Mo added filtration is about 30 μm; this value was most likely chosen in an empirical way as an acceptable compromise in order to avoid high dose, tube overloading and poor image quality. The improvement of the X-ray tube output due to the introduction of new Mo rotating anode and high frequency voltage generator, together with a faster screen-film system, prompted us to investigate the effect of increasing Mo filtration on dose and image quality. In this paper we analyzed the energy spectra distribution for various kV(p) settings with Mo filtration ranging from 0 to 75 μm. The analysis was performed on either an incident or transmitted beam. The entrance dose, the mean dose, the mean glandular dose and the image quality were also evaluated. The results show that at increasing filter thickness the entrance and the mean dose decrease without losing image quality. In addition, the mean glandular dose appears to be dependent on the kV(p) settings, but is almost independent on Mo filtration