Accuracy of 3D reproduction of natural head position using three different manual reorientation methods compared to 3D software

Abstract

PurposeThe aim of this study was to analyze the positional differences of three-dimensional (3D) natural head positions (NHPs) reproduced by three different manual reorientation methods without special software by the Pose from Orthography and Scaling with ITerations (POSIT) method. MethodsFive ceramic markers were attached to each of 12 patients’ faces, and frontal and lateral photographs in the NHP and 3D computed tomography (CT) were taken. The 3D surface model was reoriented for the NHP reproduction by four different methods: the POSIT method (standard method), the location of the markers (A), the soft tissue landmarks (B) on the photographs, and manual correction without photographs (C). On each 3D surface model, the location of the skull was evaluated three-dimensionally. ResultsDifferences between reproduced NHPs in each of the four different methods were statistically significant (p < 0.0001). Compared to the POSIT method, the accuracy of the other reproducing methods was lower. The A and B methods showed a similar accuracy to each other, while the C method presented the most inaccurate NHP. ConclusionIf 3D NHP reproduction using special software is impossible, reproducing NHP with photographs may be used as an alternative method, but its application should be clinically limited.