The effects of spectral distribution on x-ray image quality

Broad and monoenergetic x-ray spectra were analyzed with a computer to determine the photon signal-to-noise ratio, exposure modulation, and integral dose in a simulated caries detection task. Assuming an ideal exposure geometry, it was possible to compute relative values which permit meaningful comparison of spectra in terms of these parameters. The broad spectra were measured with a high-resolution spectrometer system. The data were corrected for spurious effects and analyzed with an idealized attenuation model. The results suggest that spectral changes brought about by even relatively small amounts of selective filtration in region between 25 and 45 keV. measurably influence the potential for diagnostic quality.