Photogrammetric evaluation in clinical genetics: Theoretical considerations and experimental results
✍ Scribed by Diliberti, John H. ;Olson, David P.
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 664 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0148-7299
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✦ Synopsis
As newer mathematical approaches are applied to the field of clinical genetics accurate methods of craniofacial measurement are increasingly necessary. If photogrammetric techniques are to be used certain theoretical and practical issues must be taken into account. Errors due to projection are particularly important, but systematic and random errors must also be considered. We discuss theoretical aspects of projection errors along with experimental measurements. Systematic errors in excess of 20% were found during simulations of typical clinical conditions, although smaller errors were obtained using techniques practical in a clinical setting. Photogrammetric measurements are potentially valuable in the field of clinical genetics but must be used cautiously.
KEY WORDS: dysmorphology, anthropometry, photogrammetry, congenital anomalies
proach chosen will undoubtedly determine the precision of the measurements necessary for reproducible analysis. Since the field of mathematical analysis in this area is quite new, no firm guidelines for precision of measurements have been determined. These guidelines will undoubtedly develop over the next few years as mathematical approaches becomes more common and more refined. In the meantime, research done in this field must use rigorous approaches to data collection in order to avoid potential bias in analysis.
The most common approaches to craniofacial measurements include the methods of classical physical anthropology, anthropometry, as well as photogrammetry, and radiography (along with the related methods: magnetic resonance imaging, ultrasonography, etc.). Obviously only the first 2 techniques will generally be applied directly by the clinical geneticist. Although each approach has been used in the study of disorders of morphogenesis, discussions of measurement errors from theoretical and practical perspectives have been limited. We have examined the systematic errors in the photogrammetric approach and present the results below.