Comment on 'Perspectives of medical X-ray imaging'

In the paper 'Perspectives of medical X-ray imaging' (Nucl. Instr. and Meth. A 466 (2001) 99) the authors infer, from simple approximations, that the use of HOPG monochromator has no advantage in mammography compared to existing systems. We show that in order to compare imaging properties of different X-ray sources it is necessary to evaluate the spectra after the attenuation of the tissue to be imaged. Indeed, quasi-monochromatic X-ray sources have the potential to enhance image contrast and to reduce patient dose