Application of added beam filtration to intra-oral radiography.

Laboratory studies of Lanex Regular screen, gadolinium foil, yttrium foil and an erbium composite material were performed as added beam filters to identify which would prove most effective in reducing exposure without reducing diagnostic image quality. Images of comparable densities produced with both D- and E-speed films were evaluated for contrast, resolution, reduction in relative skin exposure and subjective image quality. Reductions in skin exposure ranged from 25% to 71% depending on the filter, kVp and film type when compared with an image produced with a standard aluminium filtered beam at 70 kVp with D-speed film. This study concluded that the use of Lanex screen or yttrium foil as added beam filtration has the potential to reduce patient skin exposure by 50% of that from the currently recommended E-speed film and rectangular collimation, while still producing diagnostically acceptable images.