Effect of tungsten absorption edge filter on diagnostic x-ray spectra, image quality and absorbed dose to the patient.

The X-ray spectra from a tungsten-target diagnostic tube were measured with a lithium-drifted silicon detector. Four characteristic X-ray peaks were clearly observed. When a 0.05-0.3 mm thick tungsten absorption edge filter was added to the tube, the number of photons in the spectra above the K-absorption edge decreased dramatically. The effect of the absorption edge filter on image quality and on the absorbed dose were investigated by both measurement and Monte Carlo calculation. The absorbed dose to the patient is reduced without image quality, being degraded.