A critical appraisal of measurement of the soft tissue outline using photographs and video

Radiographs are essential in the planning and assessment of treatment, as well as the study of growth patterns, but before subjecting a child to X-rays, the clinician must ensure that it is justifiable on clinical grounds. The use of cephalometric radiography, particularly in the young patient with a cleft of the lip and/or palate, has been questioned. The aim of this project was to investigate the validity and reproducibility of using a photograph or video image, compared with a radiograph, for measurement of the soft tissue profile of the face. A radiographic phantom head was used, which consisted of a dry bone skull encased in a soft tissue substitute. The method involved comparing direct measurement of the head in a Reflex Metrograph with the results of computerized digitizing of a cephalometric radiograph, digitizing a video image from a computer screen and measurement of a photograph. It was found that digitizing of the soft tissue outline of a radiographic phantom head from a video image was neither a valid, nor a reproducible method of replacing cephalometric radiographs in the measurement of the soft tissue profile of the face. A photograph may be a clinically acceptable alternative, but errors from this method are likely to be larger than those due to digitization of a radiograph.