A new method for the comparison of bone loss measurements on nonstandardized radiographs

Abstract

A mathematical algorithm was derived which allows comparison of measurements of bone loss from sequential non‐standardized radiographs. The same three anatomical landmarks were defined on both a reference and an alternate radiograph. These coordinates were used to compute a transformation matrix which mathematically “bent” the alternate radiograph to fit the reference radiograph in 44 pairs of non‐standardized radiographs. Comparison of direct measurements of bone loss in reference and alternate radiographs revealed a mean error of 0.55 mm. This error was significantly reduced to 0.15 mm when direct measurements in reference films were compared to transformed measurements on the alternate radiograph. These data indicate the transformation method may be of value in comparing non‐standardized radiographs.