[The use of copper and niobium filters in diagnostic x-ray equipment. A comparison of dose reduction, tube loading and picture quality].

A dose-reducing niobium filter for use in diagnostic radiology was introduced in Norway in 1989. The effect of this filter was compared with that of an ordinary copper filter. Either a 0.05 mm niobium filter or a 0.10 mm copper filter was placed into the beam from an X-ray tube. Parallel measurements were made of dose reduction to the patient, image quality and tube loading. The copper filter reduced skin doses more than the niobium filter did, and caused less increase in tube loading. The resulting image quality was considered to be the same. We conclude that a 0.10 mm copper filter is better than a niobium filter in achieving a considerable dose reduction to the patient, and is far less expensive.