Attenuation equalizing filter in diagnostic radiography. Advantages calculated by a Monte Carlo technique.

The value of an attenuation equalizing filter (equalizer) has been examined by calculation using a Monte Carlo technique. The contrast enhancement caused by the equalizer is the net result of three factors: (1) The first factor arises from the contrast change caused by the difference in detector characteristics at the different energies absorbed in the detector with and without equalizer. (2) The second factor is due to the contrast change caused by the different ratios of primary to total radiation reaching the detector. (3) Finally, the third factor describes how the transparency of the object is changed by the different primary filtration with equalizer. An example is given of the reduction in radiation energy absorbed by the patient and the question of how far the attenuation equalization can be driven is discussed.