Effect of a Multiple-Scanning Beam Device and Trough Filter on Scatter in Chest Radiography

The use of a trough compensation filter to reduce the large difference in x-ray transmission between the lung parenchyma and mediastinum results in beam hardening and increased scattered radiation which causes a reduction of subject contrast in the lung fields. When the Rotating Aperture Wheel (RAW) multiple-scanning-beam device is used with the filter, this image degradation in the lung fields can be prevented while obtaining improved visualization of the mediastinum. Quantitative comparisons of image contrast and scatter distributions over chest radiographs obtained using various com-binations of anti-scatter device and filter are examined.