Erbium filtration in iodine contrast studies.

In iodine contrast studies, an improvement in contrast is theoretically possible by narrowing the energy spectrum around the k-edge of iodine. Heavy metal filtration is a method of narrowing the energy spectrum but other parameters of the examination may be altered. These other parameters must be examined. After establishing the effect of heavy metal (erbium) filtration on the beam energy, the filter is evaluated in a simulated clinical situation. Patient exposure, image contrast, and tube loading are monitored while obtaining radiographs of a phantom comparable to a standard radiograph of the phantom. From this study, it was determined that erbium filtration could be used to decrease patient exposure markedly without significant loss of contrast or an increase in tube loading. Also determined was a set of exposure factors at which the erbium filtration was most effective.