A FILTER ARRANGEMENT IN A RADIOGRAPHY APPARATUS

摘要

The invention relates to a filter arrangement in a radiography apparatus in order to define the intensity of the radiation beam incident upon the object. To the movable filter part in front of the radiation source (2) there is coupled an electric circuit element, for example a potentiometer, from which the signal is applied further to a row (8) of light-emitting diodes in the vicinity of the object to be radiographed, for example the patient's head (7). When the filter is moved, the electric signal controls the light-emitting diodes so that the light-emitting diodes which become illuminated in the row will indicate the boundary of the filtered radiation beam at a given time.