Paris Descartes University - Sorbonne Paris Cité, EA 2496 - Orofacial Pathologies, Imaging and Biotherapies Lab, Montrouge, France and Dental Medicine Department - Bretonneau Hospital, HUPNVS, AP-HP, Paris, France.
Division of Oral Radiology, Faculdade São Leopoldo Mandic, Instituto de Pesquisas São Leopoldo Mandic, Campinas, Sao Paulo, Brazil.
Sci Rep. 2019 Apr 2;9(1):5521. doi: 10.1038/s41598-019-41949-w.
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.
锥形束 CT（CBCT）在口腔颌面儿科评估中得到了广泛应用，尽管低剂量辐射暴露的风险存在不确定性。本研究旨在通过研究不同 CBCT 采集方案对优化儿科辐射暴露的临床性能，以评估不同 CBCT 采集方案的临床性能。使用 CBCT 设备对定制的人体模型进行扫描，共涉及 6 种方案。将 CT 切片进行盲法、随机化处理，然后呈现给 3 位观察者，他们使用 4 分制对图像质量进行评分，并评估其置信度。还使用含有空气/PMMA 边的测试物体测量锐度水平。通过使用先前验证的儿科体素模型定制的蒙特卡罗（MC）框架计算有效剂量。结果表明，即使在降低曝光参数（kVp 和 mAs）的情况下，使用较小体素尺寸（180 µm）的方案仍显示出较高的图像质量评分和提高的锐度。MC 分析表明，随着曝光参数的降低，有效剂量逐渐降低，特别是当组合使用 70 kVp、16 mAs 和 180 µm 体素尺寸的方案时，平均降低 45%。相比之下，当使用较大体素尺寸（400 µm）和较低 mAs（7.4 mAs）的两种“超低剂量”方案时，均表现出最低的评分和高水平的置信度，不适合进行解剖学方法。总之，在保持儿科 CBCT 所需的图像质量的同时，可以显著降低有效剂量。
