Evaluation of rare earth intensifying screens in cephalometric radiography

Accuracy of cephalometric landmark location was determined in 20 pairs of headfilms, measuring differences in 18 points in two planes of each, using five independent observers. Each pair had one film taken with a conventional (calcium tungstate) intensifying screen system and one taken with a rare earth system. Statistically significant differences in accuracy were found in only six of the 36 measurements. Three of the differences favored the accuracy of the rare earth system (Pogonion Y, S Pogonion X and Y), while the other three favored the conventional system (ANS-X, Nasion-Y, Pt.A-Y). The least reproducible point in both systems in the horizontal axis was condylion. Since these findings showed no landmark accuracy preference of one screen system over the other, the 96 percent reduction in patient radiation with the rare earth system would mandate this be used in cephalometric radiography.