A method for correction of radiographic errors in serial three-dimensional cephalometry

OBJECTIVES: To improve the accuracy of location of anatomical structures in serial three-dimensional (3D) cephalometric radiography. METHODS: A new method was developed to correct for geometrical errors in the calculation of the 3D coordinates of a point viewed on any two of three frontal, lateral and axial cephalometric radiographs. A computer-based method was used to reduce measurement errors. The methods were tested on a phantom containing metallic markers and on a dried skull. RESULTS: The mean corrected geometric error was 0.43 mm (SD 0.25 mm) compared with a maximum of 8 mm (SD 0.2 mm) when calculated directly from the radiographs. The mean computer-based measurement error was 0.46 mm (SD 0.34 mm) compared with 1.38 mm (SD 0.74 mm) when made directly from the radiographs. CONCLUSIONS: The new method for the correction of radiographic errors in 3D serial cephalometric radiography appears to be sufficiently accurate to justify clinical evaluation.