Abstract
The purpose of this study was to investigate the effect of heavy metal filters for patient dose reduction and improving image contrast in digital radiography using a CsI based flat panel detector. The heavy metal filters used in this study were gadolinium, holmium, and ytteribium. These filters have a K-absorption edge in the range from 50 to 70 keV. Also, images without filters and images with conventional copper filter were obtained for comparative study. Iodine-water contrast and patient skin dose were measured in each combination of tube voltage（70and80kV）and filters. Compared with the condition of 80 kV tube voltage without filter, the combination of 80 kV tube voltage and holmium or ytteribium filter reduced patient skin dose by 35% without degrading image contrast. And the combination of 70 kV and ytteribium filter achieved improvement of the iodine-water contrast by 22% and a dose reduction of 8% compared with the condition of 80 kV tube voltage without filter. Appropriate additional heavy metal filters for digital radiography when using flat panel detectors can reduce patient dose without degrading image contrast.
