title: Radiation dose of cone-beam computed tomography compared to conventional radiographs in orthodontics.
abstract: OBJECTIVE
  The aim of this study was to determine radiation doses of different cone-beam computed tomography (CBCT) scan modes in comparison to a conventional set of orthodontic radiographs (COR) by means of phantom dosimetry.
  
  
  METHODS
  Thermoluminescent dosimeter (TLD) chips (3 × 1 × 1 mm) were used on an adult male tissue-equivalent phantom to record the distribution of the absorbed radiation dose. Three different scanning modes (i.e., portrait, normal landscape, and fast scan landscape) were compared to CORs [i.e., conventional lateral (LC) and posteroanterior (PA) cephalograms and digital panoramic radiograph (OPG)].
  
  
  RESULTS
  The following radiation levels were measured: 131.7, 91, and 77 μSv in the portrait, normal landscape, and fast landscape modes, respectively. The overall effective dose for a COR was 35.81 μSv (PA: 8.90 μSv; OPG: 21.87 μSv; LC: 5.03 μSv).
  
  
  CONCLUSIONS
  Although one CBCT scan may replace all CORs, one set of CORs still entails 2-4 times less radiation than one CBCT. Depending on the scan mode, the radiation dose of a CBCT is about 3-6 times an OPG, 8-14 times a PA, and 15-26 times a lateral LC. Finally, in order to fully reconstruct cephalograms including the cranial base and other important structures, the CBCT portrait mode must be chosen, rendering the difference in radiation exposure even clearer (131.7 vs. 35.81 μSv). Shielding radiation-sensitive organs can reduce the effective dose considerably.
  
  
  CONCLUSIONS
  CBCT should not be recommended for use in all orthodontic patients as a substitute for a conventional set of radiographs. In CBCT, reducing the height of the field of view and shielding the thyroid are advisable methods and must be implemented to lower the exposure dose.
authors.affiliation: Clinic for Orthodontics and Pediatric Dentistry, Center for Dental Medicine, University of Zurich, Plattenstrasse 11, 8032, Zurich, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Signorelli
authors.affiliation: Clinic for Orthodontics and Pediatric Dentistry, Center for Dental Medicine, University of Zurich, Plattenstrasse 11, 8032, Zurich, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Patcas
authors.affiliation: Dental and Oral Diseases Outpatient Clinic, Department of Eye, Ear and Oral Diseases, Hospital and Department of Otolaryngology, Tampere University, Tampere, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Peltomäki
authors.affiliation: Clinic for Orthodontics and Pediatric Dentistry, Center for Dental Medicine, University of Zurich, Plattenstrasse 11, 8032, Zurich, Switzerland. marc.schaetzle@zzm.uzh.ch.
authors.forename: Marc
authors.initials: M
authors.lastname: Schätzle
mesh_terms: D000328:Adult; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008297:Male; D009970:Orthodontics / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis*; D011862:Radiography, Panoramic / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation / Q000379:methods*
keywords: Diagnostic techniques; Organs at risk; Phantoms, imaging; Radiation dosage; Thyroid