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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.