Comparison between KEY and copper plus aluminium filters

The KEY-filter (KF) is said to greatly reduce exposure dose by absorbing x-rays in the low energy region, where there is an undesirable increase in exposure. This effect has been reported by various workers. In this study, the effects of the KF on transmitting x-ray spectrum, various doses, fluorescence, exposure condition, etc., were compared with those of filters consisting of copper plus aluminium. Materials composing the KF were also estimated from the spectrum of scattering x-rays. The experimental results showed no difference between the KF and the copper-plus-aluminium filter on any item examined. Characteristic x-rays of copper and tin were observed in the scattering x-ray spectrum of the KF. Accordingly, it seems that the copper-plus-aluminum filter can be substituted for the KF. (author)