Soontra Panmekiate1, Peera Rungwittayathon1, Wijuck Suptaweeponboon1, Nattarus Tangtraitham1, Ruben Pauwels2. 1. Department of Radiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. 2. Department of Radiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand; OMFS-IMPATH Research Group, Faculty of Medicine, Department of Imaging and Pathology, KU Leuven and Oral and Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium; Mechanical Engineering Department, Catholic University of Leuven, Leuven, Belgium. Electronic address: pauwelsruben@hotmail.com.
Abstract
OBJECTIVE: The aim of this study was to find the optimal balance among tube voltage (kV), tube current (mA), and exposure time (s) in cone beam computed tomography (CBCT). STUDY DESIGN: Three human hemimandibles were scanned by using the 3D Accuitomo 170 scanner (J. Morita, Kyoto, Japan). First, 3 combinations of kilovolt (kV) and milliampere (mA) were used at a constant radiation dose. Seven observers evaluated the images; the kV of the highest-scoring scan was considered optimal. Second, the lowest acceptable mA for visualizing different anatomic structures was determined. Finally, the samples were scanned by using 3 combinations of tube current and exposure time; the observers determined the combination with the highest image quality. RESULTS: At a constant radiation dose, the highest available voltage (i.e., 90 kV) resulted in the highest image quality in terms of general impression, sharpness, noise, and artefacts. Depending on the anatomic structure, mA reductions of 20% to 40% compared with the default setting were possible. Fast-scan protocols showed equal or slightly better image quality compared with the standard-scan mode. CONCLUSIONS: For the CBCT model used in this study, optimization implies the use of the highest kV along with the shortest exposure time and a task-specific mA. The proposed stepwise optimization approach could be applied to any CBCT unit, preferably during commissioning.
OBJECTIVE: The aim of this study was to find the optimal balance among tube voltage (kV), tube current (mA), and exposure time (s) in cone beam computed tomography (CBCT). STUDY DESIGN: Three human hemimandibles were scanned by using the 3D Accuitomo 170 scanner (J. Morita, Kyoto, Japan). First, 3 combinations of kilovolt (kV) and milliampere (mA) were used at a constant radiation dose. Seven observers evaluated the images; the kV of the highest-scoring scan was considered optimal. Second, the lowest acceptable mA for visualizing different anatomic structures was determined. Finally, the samples were scanned by using 3 combinations of tube current and exposure time; the observers determined the combination with the highest image quality. RESULTS: At a constant radiation dose, the highest available voltage (i.e., 90 kV) resulted in the highest image quality in terms of general impression, sharpness, noise, and artefacts. Depending on the anatomic structure, mA reductions of 20% to 40% compared with the default setting were possible. Fast-scan protocols showed equal or slightly better image quality compared with the standard-scan mode. CONCLUSIONS: For the CBCT model used in this study, optimization implies the use of the highest kV along with the shortest exposure time and a task-specific mA. The proposed stepwise optimization approach could be applied to any CBCT unit, preferably during commissioning.