Ruben Pauwels1, Reinhilde Jacobs2, Ria Bogaerts3, Hilde Bosmans4, Soontra Panmekiate5. 1. Lecturer, Department of Radiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand; OMFS-IMPATH Research Group, Department of Imaging and Pathology, Faculty of Medicine, University of Leuven and Department of Oral and Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium. Electronic address: pauwelsruben@hotmail.com. 2. Professor, OMFS-IMPATH Research Group, Department of Imaging and Pathology, Faculty of Medicine, University of Leuven and Department of Oral and Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium. 3. Professor, Laboratory of Experimental Radiotherapy, Department of Oncology, Biomedical Sciences Group, University of Leuven, Leuven, Belgium. 4. Professor, Medical Physics & Quality Assessment, Department of Imaging and Pathology, Biomedical Sciences Group, University of Leuven, Leuven, Belgium. 5. Professor and Head, Department of Radiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Abstract
OBJECTIVE: To measure the effect of field of view (FOV) size and position on scatter-induced image noise in cone beam computed tomography (CBCT). STUDY DESIGN: A polymethyl methacrylate (PMMA) phantom containing air and aluminum underwent CBCT scanning, using seven FOVs ranging between 4 × 4 cm and 14 × 10 cm, positioned both centrally and according to a dental scan. Signal difference to noise ratio (SDNR) was measured on two-dimensional (2-D) projection images. RESULTS: At a central position, SDNR decreased with increasing FOV size, ranging between 9.8 (14 × 10 cm) and 10.9 (4 × 4 cm). For dental FOV positions, SDNR values were between 6.3 (14 × 10 cm) and 9.5 (4 × 4 cm). To reach a constant SDNR, a dose reduction up to 76% was possible for small FOVs compared with the 14 × 10 cm FOV. CONCLUSIONS: The use of small FOVs and peripheral FOV positioning decreases scatter at the detector, resulting in a considerable potential for reduction of radiation dose to the patient.
OBJECTIVE: To measure the effect of field of view (FOV) size and position on scatter-induced image noise in cone beam computed tomography (CBCT). STUDY DESIGN: A polymethyl methacrylate (PMMA) phantom containing air and aluminum underwent CBCT scanning, using seven FOVs ranging between 4 × 4 cm and 14 × 10 cm, positioned both centrally and according to a dental scan. Signal difference to noise ratio (SDNR) was measured on two-dimensional (2-D) projection images. RESULTS: At a central position, SDNR decreased with increasing FOV size, ranging between 9.8 (14 × 10 cm) and 10.9 (4 × 4 cm). For dental FOV positions, SDNR values were between 6.3 (14 × 10 cm) and 9.5 (4 × 4 cm). To reach a constant SDNR, a dose reduction up to 76% was possible for small FOVs compared with the 14 × 10 cm FOV. CONCLUSIONS: The use of small FOVs and peripheral FOV positioning decreases scatter at the detector, resulting in a considerable potential for reduction of radiation dose to the patient.