The three-dimensional cephalogram: Theory, techniques, and clinical application

Abstract

The Broadbent-Bolton, cephalostat produces intrinsically three-dimensional information about cranial form. Yet in the clinical setting, this information hass been used primarily two dimensions at a time in the separate study of lateral or posteroanterior cephalograms. In this article we demonstrate an expedient use of existing cephalostat-based data sets to derive certain analyses of three-dimensional form. The technique is essentially the same as that of the Broadbent-Bolton "Orientator", an exploitation of the geometry of the cephalostat to simulate stereophotogrammetry. The three-dimensional method supports the usual biometrics of landmark locations, and takes advantage of a normative data base that is suited for semiautomatic analysis of syndromic data. The principal drawback of the method is its inability to represent curving form in three dimensions. However, in comparison with computed tomography (CT), it involved low radiation dose, is simpler to obtain, has an available normative data base, and is more practical for quantitative or long-term serial analysis.