Ultra-low-dose routine pediatric radiography utilizing a rare-earth filter

Clinical evaluation of the usefulness of primary beam filtration with erbium to achieve marked reductions in radiation exposure and dosage was undertaken. We evaluated 250 routine pediatric radiographic and 100 contrast examinations. An additional 52,727 radiographic and 4745 fluoroscopic examinations were analyzed prospectively by evaluation of subjective film quality. Radiation exposure and dosage reductions ranged from 57% at 50 kVp to 36% at 80 kVp and 39% at 120 kVp. These reductions were obtained in addition to those previously attained by using a 600-speed gadolinium oxysulphide screen/film system (Trimax 12, XDL). The erbium filter requires that the tube current be increased to approximately double that without the filter (in the most commonly used range of 60-100 kVp). However, tube loading is already so low with the 600 system that this effect on wear is considered inconsequential. This ultra-low-dose rare-earth beam filter and screen/film combination results in films with no demonstrable loss of overall quality, plus a subjective slight improvement in contrast definition for iodine and barium contrast studies. The addition of erbium foil beam filtration to existing rare-earth screen/film technology results in what is currently the ultimate in low-dose conventional radiographic imaging.