Abstract
An X-ray apparatus includes an X-ray source for producing a beam of X-rays, an X-ray detector for detecting this radiation, and an X-ray filter with filter elements which is arranged between the X-ray source and the X-ray detector so as to attenuate the X-ray beam in each independent filter element individually. Each filter element can contain a liquid filling (22) which is electrically conductive and X-ray absorbing, the value of the X-ray absorptivity of each filter element being discretely adjustable by step-wise adjustment of the level of the liquid filling within each filter element. Each filter element includes an electrode (23) which is positioned between an isolator layer (34) and a substrate (38) in a wall of the filter element in order to apply an electric potential to the wall of this element. Another electric potential is applied to the liquid filling. Therefore, an electric capacitance can be defined per unit of surface area of the filter element. In order to achieve step-wise filling of the filter element, in accordance with the invention the electric capacitance per unit of surface area of the filter element is varied in its longitudinal direction z. This is realized, for example, by subdividing the electrode (23) into electrode segments of different surface area in the longitudinal direction z of the filter element, the first electrode segment (37) having a surface area which is larger than that of the second electrode segment (39). [on SciFinder (R)]
| Original language | English |
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| Publication status | Published - 26 Apr 2001 |