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 chil d to X-rays, the clinician must ensure that it is justifiable on clini cal grounds. The use of cephalometric radiography, particularly in the young patient with a cleft of the lip and/or palate, has been questio ned. The aim of this project was to investigate the validity and repro ducibility of using a photograph or video image, compared with a radio graph, for measurement of the soft tissue profile of the face. A radio graphic phantom head was used, which consisted of a dry bone skull enc ased in a soft tissue substitute. The method involved comparing direct measurement of the head in a Reflex Metrograph with the results of co mputerized digitizing of a cephalometric radiograph, digitizing a vide o image from a computer screen and measurement of a photograph. It was found that digitizing of the soft tissue outline of a radiographic ph antom head from a video image was neither a valid, nor a reproducible method of replacing cephalometric radiographs in the measurement of th e soft tissue profile of the face. A photograph may be a clinically ac ceptable alternative, but errors from this method are likely to be lar ger than those due to digitization of a radiograph.