Evaluation of Image Quality Parameters of Small and Full Field of View Cone Beam Computed Tomography Dental Imaging Systems
E Hoffmann1*, A Marques da Silva1, D Azevedo1, J Borges2, (1) Pontificia Universidade Catolica do RS, Porto Alegre, RS, (2) Prototipos 3D, Porto Alegre, RSSU-E-I-14 Sunday 3:00:00 PM - 6:00:00 PM Room: Exhibit Hall
Purpose: CBCT systems are being used in dental preoperative planning, which rely on 3D surface model representations of the jaw, using a segmentation algorithm for extracting the bony tissues. However, CBCT systems have differences of imaging parameters, which affect the image quality and segmentation process, influencing the accuracy of the 3D surface models used in preoperative implant planning. The purpose of this study was to evaluate image quality parameters of different types of CBCT systems, showing their potentialities and limitations for preoperative planning.
Methods: Images were acquired using the systems: i-CAT (Imaging Sciences International Inc., USA); ProMax 3Ds (Planmeca Oy, Finland); Kodak 9500 Cone Beam 3D and Kodak 9000C Cone Beam 3D (Kodak Dental Systems, USA). CBCT systems were divided into categories, related to their field of view size: Small Field of View (SFOV) and Full Field of View (FFOV) systems. Image quality parameters evaluated were: CT number accuracy, uniformity, noise level, and artifacts. Measurements were performed in slices around the center of the phantom.
Results: CT numbers are highly affected by the amount of mass outside the reconstructed volume, confirming the relation between density variability and imaging volume. The mean CT number shows little correspondence to that of the traditional CT protocols. The variability is especially high in the case for SFOV systems. Uniformity artifacts occur at the top or bottom of the FOV, and result in voxel values that are unsuitable for CT number accuracy analysis. SFOV systems showed a higher noise level (11,9%) comparing to FFOV systems (4.4%).
Conclusion: The experiments showed that the size and position of the FOV affect the image quality for all CBCT systems. The study was limited to the CBCT systems that were accessible when this study was conducted. Whether new CBCT systems models would perform differently remains to be investigated.