title: Dosimetry of Three Cone Beam Computerized Tomography Scanners at Different Fields of View in Terms of Various Head and Neck Organs.
abstract: BACKGROUND
  Marketing new radiography devices necessitates documenting their absorbed X-ray doses. Since the current literature lacks studies on new devices, we assessed the doses of two new devices that had not previously been assessed.
  
  
  OBJECTIVE
  The new devices were compared to the Promax three dimensional (3D) scanner at two fields of view (FOV) in nine critical head and neck tissues and organs.
  
  
  METHODS
  Seventeen thermoluminescence dosimeters positioned in an average-sized male RANDO phantom were used to determine the dosimetry of the three cone beam computerized tomography devices (NewTom VGi, NewTom 5G, and Promax 3D) at two field of views (FOVs), one small and one large. The exposure by each device per FOV was performed five times (30 exposures). The absorbed and effective doses were calculated for the thyroid, parotid, submandibular gland, sublingual gland, calvarium, cervical vertebra, trunk of the mandible, and mandibular ramus. The doses pertaining to the different devices, the FOVs, and the tissues were compared using the Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests.
  
  
  RESULTS
  The average absorbed doses, respectively, for the large and small FOVs were 17.19 and 28.89 mGy in the Promax 3D, 19.25 and 35.46 mGy in the NewTom VGi, and 18.85 and 30.63 mGy in the NewTom 5G. The absorbed doses related to the FOVs were not significantly different (P value = 0.1930). However, the effective doses were significantly greater at the smaller FOVs / higher resolutions (P = 0.0039). The doses of the three devices were not significantly different (P = 0.8944). The difference among the nine organs/tissues was significant (Kruskal-Wallis P=0.0000).
  
  
  CONCLUSIONS
  The absorbed doses pertaining to the devices and the FOVs were not significantly different, although the organs/tissues absorbed considerably different doses.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Dental Faculty, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Sima
authors.initials: S
authors.lastname: Nikneshan
authors.affiliation: Department of Radiation Medicine, Shahid Beheshti University, Tehran, Iran.
authors.forename: Mahmood Reza
authors.initials: MR
authors.lastname: Aghamiri
authors.affiliation: Department of Oral and Maxillofacial Radiology, Dental Faculty, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Moudi
authors.affiliation: Department of Oral and Maxillofacial Radiology, Dental Faculty, Alborz University of Medical Sciences, Karaj, Iran.
authors.forename: Nika
authors.initials: N
authors.lastname: Bahemmat
authors.affiliation: Department of Oral and Maxillofacial Radiology, Dental Faculty, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Hoora
authors.initials: H
authors.lastname: Hadian
keywords: Absorbed Dose; Cone Beam Computed Tomography; Dosimetry; Effective Dose; Field of View; Resolution