title: Impact of prone, supine and oblique patient positioning on CBCT image quality, contrast-to-noise ratio and figure of merit value in the maxillofacial region.
abstract: OBJECTIVE
  To assess the impact of supine, prone and oblique patient imaging positions on the image quality, contrast-to-noise ratio (CNR) and figure of merit (FOM) value in the maxillofacial region using a CBCT scanner. Furthermore, the CBCT supine images were compared with supine multislice CT (MSCT) images.
  
  
  METHODS
  One fresh frozen cadaver head was scanned in prone, supine and oblique imaging positions using a mobile CBCT scanner. MSCT images of the head were acquired in a supine position. Two radiologists graded the CBCT and MSCT images at ten different anatomical sites according to their image quality using a six-point scale. The CNR and FOM values were calculated at two different anatomical sites on the CBCT and MSCT images.
  
  
  RESULTS
  The best image quality was achieved in the prone imaging position for sinus, mandible and maxilla, followed by the supine and oblique imaging positions. 12-mA prone images presented high delineation scores for all anatomical landmarks, except for the ear region (carotid canal), which presented adequate to poor delineation scores for all studied head positions and exposure parameters. The MSCT scanner offered similar image qualities to the 7.5-mA supine images acquired using the mobile CBCT scanner. The prone imaging position offered the best CNR and FOM values on the mobile CBCT scanner.
  
  
  CONCLUSIONS
  Head positioning has an impact on CBCT image quality. The best CBCT image quality can be achieved using the prone and supine imaging positions. The oblique imaging position offers inadequate image quality except in the sinus region.
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery/Oral Pathology and 3D Innovation Lab, VU University Medical Center, Amsterdam, Netherlands.
authors.forename: Juha
authors.initials: J
authors.lastname: Koivisto
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery/Oral Pathology and 3D Innovation Lab, VU University Medical Center, Amsterdam, Netherlands.
authors.forename: Maureen
authors.initials: M
authors.lastname: van Eijnatten
authors.affiliation: 2 Medical Imaging Center, Department of Radiology, Tampere University Hospital, Tampere, Finland.
authors.forename: Jorma
authors.initials: J
authors.lastname: Järnstedt
authors.affiliation: 2 Medical Imaging Center, Department of Radiology, Tampere University Hospital, Tampere, Finland.
authors.forename: Kirsi
authors.initials: K
authors.lastname: Holli-Helenius
authors.affiliation: 2 Medical Imaging Center, Department of Radiology, Tampere University Hospital, Tampere, Finland.|3 University of Tampere, Medical School, Tampere, Finland.
authors.forename: Prasun
authors.initials: P
authors.lastname: Dastidar
authors.affiliation: 1 Department of Oral and Maxillofacial Surgery/Oral Pathology and 3D Innovation Lab, VU University Medical Center, Amsterdam, Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Wolff
mesh_terms: D002102:Cadaver; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation*; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D056888:Patient Positioning / Q000379:methods*; D016684:Prone Position; D016683:Supine Position
keywords: CBCT; CNR; FOM; MSCT; image quality