Effect of cephalometer misalignment on calculations of facial asymmetry.
Introduction: In this study, we evaluated errors introduced into the interpretation of facial asymmetry on posteroanterior (PA) cephalograms due to malpositioning of the x-ray emitter focal spot. We tested the hypothesis that horizontal displacements of the emitter from its ideal position would prod...
| Publicado en: | American Journal of Orthodontics & Dentofacial Orthopedics Vol. 132; no. 1; pp. 15 - 28 |
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| Autores principales: | , , , , , , , , , , , |
| Formato: | research Journal Article |
| Publicado: |
Elsevier B.V.
Jul2007
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=105985605&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 105985605 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 08895406 1WT jtl: American Journal of Orthodontics & Dentofacial Orthopedics issn: 08895406 maglogo: N pubinfo: dt: Jul2007 vid: 132 iid: 1 pid: 467 pub: Elsevier B.V. place: New York, New York artinfo: ui: 105985605 NLM17628246 2009628604 10.1016/j.ajodo.2005.06.039 NLM17628246 105985605 ppf: 15 ppct: 13 formats: tig: atl: Effect of cephalometer misalignment on calculations of facial asymmetry. aug: au: Lee K Hwang H Curry S Boyd RL Norris K Baumrind S Lee, Ki-Heon Hwang, Hyeon-Shik Curry, Sean Boyd, Robert L Norris, Kevin Baumrind, Sheldon affil: Department of Orthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea sug: subj: Cephalometry Diagnostic Errors Cephalometry Equipment and Supplies Models, Theoretical Radiographic Magnification Skull Radiography Human ab: Introduction: In this study, we evaluated errors introduced into the interpretation of facial asymmetry on posteroanterior (PA) cephalograms due to malpositioning of the x-ray emitter focal spot. We tested the hypothesis that horizontal displacements of the emitter from its ideal position would produce systematic displacements of skull landmarks that could be fully accounted for by the rules of projective geometry alone. Methods: A representative dry skull with 22 metal markers was used to generate a series of PA images from different emitter positions by using a fully calibrated stereo cephalometer. Empirical measurements of the resulting cephalograms were compared with mathematical predictions based solely on geometric rules. The empirical measurements matched the mathematical predictions within the limits of measurement error (x= 0.23 mm), thus supporting the hypothesis. Based upon this finding, we generated a completely symmetrical mathematical skull and calculated the expected errors for focal spots of several different magnitudes. Quantitative data were computed for focal spot displacements of different magnitudes. Results and Conclusions: Misalignment of the x-ray emitter focal spot introduces systematic errors into the interpretation of facial asymmetry on PA cephalograms. For misalignments of less than 20 mm, the effect is small in individual cases. However, misalignments as small as 10 mm can introduce spurious statistical findings of significant asymmetry when mean values for large groups of PA images are evaluated. pubtype: Academic Journal doctype: research Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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