Abstract
Cone beam CT (CBCT) for dentomaxillofacial paediatric assessment has been widely used despite the uncertainties of the risks of the low-dose radiation exposures. The aim of this work was to investigate the clinical performance of different CBCT acquisition protocols towards the optimization of paediatric exposures. Custom-made anthropomorphic phantoms were scanned using a CBCT unit in six protocols. CT slices were blinded, randomized and presented to three observers, who scored the image quality using a 4-point scale along with their level of confidence. Sharpness level was also measured using a test object containing an air/PMMA e,dge. The effective dose was calculated by means of a customized Monte Carlo (MC) framework using previously validated paediatric voxels models. The results have shown that the protocols set with smaller voxel size (180 µm), even when decreasing exposure parameters (kVp and mAs), showed high image quality scores and increased sharpness. The MC analysis showed a gradual decrease in effective dose when exposures parameters were reduced, with an emphasis on an average reduction of 45% for the protocol that combined 70 kVp, 16 mAs and 180 µm voxel size. In contrast, both “ultra-low dose” protocols that combined a larger voxel size (400 µm) with lower mAs (7.4 mAs) demonstrated the lowest scores with high levels of confidence unsuitable for an anatomical approach. In conclusion, a significant decrease in the effective dose can be achieved while maintaining the image quality required for paediatric CBCT.
Highlights
Cone beam CT (CBCT) for dentomaxillofacial paediatric assessment has been widely used despite the uncertainties of the risks of the low-dose radiation exposures
The highest mean score values were concentrated in protocols protocol 1 (P1) to P4, whereas the protocols P5 and P6 have shown mean score values mostly below 2
Results of this research indicate that it is possible to significantly decrease radiation dose by means of technical parameter reduction, while keeping the clinical performance for paediatric diagnostic tasks, at a given level and for the CBCT model used in this study
Summary
Cone beam CT (CBCT) for dentomaxillofacial paediatric assessment has been widely used despite the uncertainties of the risks of the low-dose radiation exposures. The MC analysis showed a gradual decrease in effective dose when exposures parameters were reduced, with an emphasis on an average reduction of 45% for the protocol that combined 70 kVp, 16 mAs and 180 μm voxel size Both “ultra-low dose” protocols that combined a larger voxel size (400 μm) with lower mAs (7.4 mAs) demonstrated the lowest scores with high levels of confidence unsuitable for an anatomical approach. The aim of this study was to provide data regarding subjective image quality of some pre-selected CBCT scan protocols obtained from recently reported age-specific anthropomorphic DIMITRA phantoms[4] These data were matched with objective measurements and accurate dose quantifications based on Monte Carlo (MC) simulation[5] in order to provide optimization strategies in the paediatric dentomaxillofacial radiology field
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