PHOTOGRAMMETRIC QUANTIFICATION OF CHANGES OF SOFT TISSUE AFTER SKELETAL TREATMENT OF THE FACIAL PART OF THE SKULL

摘要

In germany, threedimensional non-invasive measurement techniques for medical purposes are not in routine use. Completely integrated applications of photogrammetric technology are still missing. In daily routine the possibilities of clinical findings, therapeutical and operative plannings are only subjective. The results of clinical examination, X-rays and prae- and postoperative photographs from different planes have been used for medical analysis. In an interdisciplinary research project we tested the general applicability of photogrammetric measurement systems. We examined patients with malformations of the mandible-maxilla complex by taking pictures from the face. In order to achieve a surface structure we projected regular patterns onto the surface. The first investigations were made in-vitro with an analog camera and the manual measurement of an analytical evaluation system. In this case we calculated about 800 points on the surface of a plaster cast with an accuracy higher than 0.4 mm. Furthermore we made comparative studies of living persons with a widely automated procedure using a digital photogrammetric recording and evaluation system. The measurement of digital image coordinates with the program PHAUST is supported by elliptical and center-of-gravity operators and shows a significant improvement of accuracy and time involved. Finally graphical analyses of measurement results are presented in a clinically relevant shape. We produce representations of the plaster casts and the faces in AutoCAD by means of regular meshes which allow any perspective view, longitudinal and lateral sections. In addition to calculating angles, distances, surfaces and volumes, the visualisation of the shape is a good help for documentation and quantification of changes of soft tissue of the human face under surgery treatment.