The Effect of Different Field of View Sizes on Contrast-to-Noise Ratio of Cone-Beam Computed Tomography Units: An In-Vitro Study
Objectives: ‘Field of view (FOV) size’ affects the quality of radiographic images and the radiation dose received by patients. In cone-beam computed tomography (CBCT) FOV should be selected according to therapeutic purposes. While aiming for the highest diagnostic image quality, the radiation dose should be kept to a minimum to reduce the risk for patients. The purpose of this study was to assess the effect of different sizes of FOV on contrast-to-noise ratio (CNR) in five different CBCT units.
Materials and Methods: In this experimental study, CBCT scans were taken from a dried human mandible containing a resin block fixed to the lingual cortex and a resin ring was used to simulate soft tissue during scans. Five CBCT units including, NewTom VGi, NewTom GiANO, Soredex SCANORA 3D, Planmeca ProMax, and Asahi Alphard 3030 were evaluated. Each unit had 3 to 5 different FOVs. Images were obtained and analyzed with ImageJ software and CNR was calculated in each image. ANOVA and T-test were used for statistical analysis (P<0.05).
Results: Comparison among different FOVs of each unit showed significant CNR reductions in small FOVs (P<0.05). Similar FOV sizes of different CBCT devices were also compared and demonstrated significant differences (P<0.05).
Conclusion: A direct relationship between FOV size and CNR was observed in all five CBCT units, but differences in exposure parameters of these units led to variable CNR in FOVs with similar sizes.
2. Bechara B, Moore WS, McMahan CA, Noujeim M. Metal artifact reduction with cone beam CT: an in-vitro study. Dentomaxillofac Radiol 2012; 41: 248-253.
3. Bechara B, McMahan CA, Geha H, Noujeim M. Evaluation of a cone beam CT artifact reduction algorithm. Dentomaxillofac Radiol 2012; 41: 422- 428.
4. White SC, Pharaoh MJ. Oral radiology: Principles and interpretation. 6th ed. St. Louis, Mo, Mosby/Elsevier, 2009, p.131.
5. Bushong SC. Radiologic science for technologists: Physics, biology and protection. 10th ed. Saint Louis, Mosby, 2013, p. 237-260.
6. Tanimoto H, Arai Y .The effect of voxel size on image reconstruction in cone-beam computed tomography. Oral Radiol 2009; 25: 149-153.
7. Bechara B, McMahan CA, Moore WS, Noujeim M, Teixeira FB, Geha H. Cone beam CT scans with and without artefact reduction in root fracture detection of endodontically treated teeth. Dentomaxillofac Radiol 2013; 42: 20120245.
8. Bechara B, McMahan CA, Moore WS, Noujeim M, Geha H. Contrast-to-noise-ratio with different large volumes in a cone beam computerized tomography machine: an in vitro study. Oral Surg Oral Med Oral Pathol Oral Radiol 2012; 114: 658–665.
9. Hassan B, Couto Souza P, Jacobs R, deAzambuja Berti S, van der Stelt P. Influence of scanning and reconstruction parameters on quality of three-dimensional surface models of the dental arches from cone beam computed tomography. Clin Oral Investig 2010; 14: 303–310.
10. Schropp L, Alyass NS, Wenzel A, Stavropoulos A. Validity of wax and acrylic as softtissue simulation materials used in in vitro radiographic studies. Dentomaxillofacial Radiology 2012; 41: 686–690.
11. Bamba J, Araki K, Endo A, Okano T. Image quality assessment of three cone beam CT machines using the SEDENTEXCT CT phantom. Dentomaxillofac Radiol 2013; 42: 20120445.
12. Bechara B, McMahan CA, Moore WS, Noujeim M, Geha H, Teixeira FB. Contrast-to-noiseratio with difference in small field of view cone beam computerized tomography machines. J Oral Sci 2012; 54:227-232.
13. Lofthang-Hansen S, Thilander-Klang A, Gröndahl K. Evaluation of subjective image quality in relation to diagnostic task for cone beam computed tomography with different fields of view. Eur J Radiol 2011; 80: 483-488.
14. Pauwels R, Silkosessak O, Jacobs R, Bogaerts R, Bosmans H, Panmekiate S. A pragmatic approach to determine the optimal kVp in cone beam CT: balancing contrast-to-noise ratio and radiation dose. Dentomaxillofac Radiol. 2014;43:20140059.
15. Schulze R, Heil U, Gross D, Bruellmann DD, Dranischnikow E, Schwanecke U, Schoemer E. Artefacts in CBCT: a review. Dentomaxillofac Radiol. 2011;40(5):265-73.
16. Siltanen S, Kolehmainen V, Järvenpää S, Kaipio JP, Koistinen P, Lassas M, Pirttilä J, Somersalo E. Statistical inversion for medical x-ray tomography with few radiographs: I. General theory. Phys Med Biol. 2003; 48:1437-63.
17. Maloul A, Fialkov J, Whyne C. The impact of voxel size-based inaccuracies on the mechanical behavior of thin bone structures. Ann Biomed Eng. 2011;39:1092-100.
18. Bauman R, Scarfe W, Clark S, Morelli J, Scheetz J, Farman A. Ex vivo detection of mesiobuccal canals in maxillary molars using CBCT at four different isotropic voxel dimensions. Int Endod J. 2011;44(8):752-8.
|Issue||Vol 19 (Continuously Published Article-Based)|
|Artifacts Cone-Beam Computed Tomography Phantoms Imaging Radiographic Image Enhancement|
|Rights and permissions|
|This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.|