Katholieke Universiteit Leuven, Department of Imaging and Pathology, OMFS-IMPATH Research Group, Campus St. Rafael, Kapucijnenvoer 33, Leuven, 3000, Belgium.
University Hospitals of Leuven, Department of Radiology, Herestraat 49, Leuven, 3000, Belgium.
Eur Radiol. 2019 Dec;29(12):7009-7018. doi: 10.1007/s00330-019-06287-5. Epub 2019 Jul 1.
To provide an indication-based and scanner-specific radiation dose and risk guide for paediatric patients undergoing dental and maxillofacial cone beam computed tomography (CBCT) examinations.
Five commercially available scanners were simulated in EGSnrc Monte Carlo (MC) code. Dedicated, in-house built, head and neck voxel models, each consisting of 22 segmented organs, were used in the study. Organ doses and life attributable risk (LAR) for cancer incidence were assessed for males and females, aged 5 to 14 years old, for every clinically available protocol: central upper and lower incisors, upper and lower premolars, upper and lower jaws, cleft palate, temporal bone, sinus, dentomaxillofacial complex, and face and skull imaging. Dose results were normalised to the x-ray tube load (mAs) and logarithmic curves were fit to organ dose and risk versus age data.
Females demonstrated higher LAR values in all cases. A well-established dose decreasing pattern with increasing age-at-exposure was observed. Central upper incisor protocols were those with the lowest risk, contrary to skull protocols which provided the highest LAR values. Salivary glands and oral mucosa were the highest irradiated organs in all cases, followed by extrathoracic tissue (ET) in protocols where the entire nasal cavity was inside the primary field. The dose to thyroid was considerably high for younger patients.
This work provides an extensive dose assessment guide for 5 dental CBCTs, enabling detailed dose assessment for every paediatric patient.
• Radiation dose concerns due to the growing use of paediatric dental and maxillofacial CBCT underline the need for justification that should in part be based on radiation exposure in radiology. • Patient-specific dose calculations based on Monte Carlo simulations and head-neck paediatric voxel models overcome the limitations of conventional thermoluminescent dosimeter (TLD) dosimetry and provide proper guidance for justification of CBCT exposures. • Monte Carlo simulations with head-neck models reveal an organ dose and radiation risk decreasing pattern with increasing age at exposure, and with decreasing size of the scanning volume of interest (field of view).
为接受口腔颌面锥形束计算机断层扫描（CBCT）检查的儿科患者提供基于指示和特定于扫描仪的辐射剂量和风险指南。
在 EGSnrc 蒙特卡罗（MC）代码中模拟了五台市售扫描仪。专门的、内部构建的头颈部体素模型，每个模型由 22 个分割的器官组成，用于该研究。评估了 5 至 14 岁男性和女性的每个临床可用方案的器官剂量和归因于癌症发病率的生命风险（LAR）：中央上、下切牙、上、下前磨牙、上颌和下颌、腭裂、颞骨、窦、牙颌面复合体以及面部和颅骨成像。将剂量结果归一化为 X 射线管负载（mAs），并对器官剂量和风险与年龄数据进行对数拟合。
在所有情况下，女性的 LAR 值都更高。观察到随着暴露年龄的增加而出现的剂量逐渐降低的模式。中央上切牙方案的风险最低，而颅骨方案的 LAR 值最高。在所有情况下，唾液腺和口腔黏膜是受照射最高的器官，其次是胸腔外组织（ET），在整个鼻腔位于主射野内的方案中更是如此。对于年轻患者，甲状腺的剂量相当高。
这项工作为 5 种口腔 CBCT 提供了广泛的剂量评估指南，能够为每个儿科患者进行详细的剂量评估。
• 由于儿科口腔颌面 CBCT 的使用日益增加，人们对辐射剂量的担忧突显了需要进行正当性论证，部分论证应基于放射科的辐射暴露。
• 基于蒙特卡罗模拟和头颈部儿科体素模型的患者特异性剂量计算克服了传统热释光剂量计（TLD）剂量测量的局限性，并为 CBCT 暴露的正当性提供了适当的指导。
• 头颈部模型的蒙特卡罗模拟显示，随着暴露年龄的增加、扫描感兴趣区域（视野）的体积减小，器官剂量和辐射风险呈下降趋势。
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