title: Influence of anatomical location on CT numbers in cone beam computed tomography.
abstract: OBJECTIVE
  To assess the influence of anatomical location on computed tomography (CT) numbers in mid- and full field of view (FOV) cone beam computed tomography (CBCT) scans.
  
  
  METHODS
  Polypropylene tubes with varying concentrations of dipotassium hydrogen phosphate (K₂HPO₄) solutions (50-1200 mg/mL) were imaged within the incisor, premolar, and molar dental sockets of a human skull phantom. CBCT scans were acquired using the NewTom 3G and NewTom 5G units. The CT numbers of the K₂HPO₄ phantoms were measured, and the relationship between CT numbers and K₂HPO₄ concentration was examined. The measured CT numbers of the K₂HPO₄ phantoms were compared between anatomical sites.
  
  
  RESULTS
  At all six anatomical locations, there was a strong linear relationship between CT numbers and K₂HPO₄ concentration (R(2)>0.93). However, the absolute CT numbers varied considerably with the anatomical location.
  
  
  CONCLUSIONS
  The relationship between CT numbers and object density is not uniform through the dental arch on CBCT scans.
authors.affiliation: Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Campinas, São Paulo, Brazil.
authors.forename: Matheus L
authors.initials: ML
authors.lastname: Oliveira
authors.forename: Guilherme M
authors.initials: GM
authors.lastname: Tosoni
authors.forename: David H
authors.initials: DH
authors.lastname: Lindsey
authors.forename: Kristopher
authors.initials: K
authors.lastname: Mendoza
authors.forename: Sotirios
authors.initials: S
authors.lastname: Tetradis
authors.forename: Sanjay M
authors.initials: SM
authors.lastname: Mallya
mesh_terms: D001641:Bicuspid / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation / Q000706:statistics & numerical data*; D003724:Dental Arch / Q000000981:diagnostic imaging*; D017886:Durapatite / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data*; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data; D007180:Incisor / Q000000981:diagnostic imaging; D008963:Molar / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D010710:Phosphates / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D011829:Radiation Dosage; D012542:Scattering, Radiation; D020390:Tooth Socket / Q000000981:diagnostic imaging*; D014965:X-Rays
chemical_list: D010710:Phosphates; D017680:Potassium Compounds; D017886:Durapatite; C013216:potassium phosphate