Improved routine chest radiography with a trough filter.

Use of the aluminum trough filter for phototimed posteroanterior chest radiographs at 120 kVp provides excellent detail within the parenchyma of the lung as well as greatly enhanced visualization of mediastinal structures on a single exposure. An improvement in overall diagnostic value was noted by a panel of radiologists in 87% of 50 cases compared with conventional 120 kVp technique. Dosimetric measurements of the entrance exposure indicate a 12.5% reduction over the mediastinum and a 62% reduction over the lateral lung field compared with routine nonfilter examinations. The filter is inexpensive and readily adapted to any x-ray unit and is, therefore, an attractive alternative to costly high kVp sources. Furthermore, the attenuation coefficient for calcium in bone and parenchyma remains relatively high with preservation of calcium contrast. Repeat exposures have been minimized and the need for additional projections virtually eliminated.