Institute of Health and Society, Newcastle University, Royal Victoria Infirmary, Queen Victoria Road, Newcastle-upon-Tyne NE1 4LP, UK; NIHR Health Protection Research Unit in Chemical and Radiation Threats and Hazards, Newcastle University, UK.
Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, UK.
Clin Radiol. 2019 Oct;74(10):816.e9-816.e17. doi: 10.1016/j.crad.2019.06.029. Epub 2019 Jul 30.
To determine cumulative scan frequencies and estimate lens dose for paediatric computed tomography (CT) head examinations in the context of potential cataract risk.
The cumulative number of head-region CT examinations among a cohort of 410,997 children and young adults who underwent CT in the UK between 1985 and 2014 was calculated. Images from a sample of these head examinations (n=668) were reviewed to determine the level of eye inclusion. Lens dose per scan was estimated using the computer program, NCICT V1.0, for different levels of eye inclusion and exposure settings typical of past and present clinical practice.
In total 284,878 patients underwent 448,108 head-region CT examinations. The majority of patients (72%) had a single recorded head-region examination. A small subset (∼1%, n=2,494) underwent ≥10 examinations, while 0.1% (n=387) underwent ≥20. The lens was included within the imaged region for 57% of reviewed routine head examinations. In many cases, this appeared to be intentional, i.e. protocol driven. In others, there appeared to have been an attempt to exclude the eyes through gantry angulation. Estimated lens doses were 20-75 mGy (mean: 47 mGy) where the eye was fully included within the examination range and 2-7 mGy (mean: 3.1 mGy) where the lens was fully excluded. Potential cumulative lens doses ranged from ∼3 mGy to ∼4,700 mGy, with 2,335 patients potentially receiving >500 mGy.
The majority of young people will receive cumulative lens doses well below 500 mGy, meaning the risk of cataract induction is likely to be very small.
在潜在白内障风险的情况下，确定小儿计算机断层扫描（CT）头部检查的累积扫描频率并估计晶状体剂量。
计算了 1985 年至 2014 年间在英国进行 CT 检查的 410997 名儿童和年轻人中头部区域 CT 检查的累积次数。对这些头部检查的样本（n=668）中的图像进行了审查，以确定眼睛包含的程度。使用 NCICT V1.0 计算机程序，根据过去和现在临床实践中典型的不同眼睛包含程度和曝光设置，估算每次扫描的晶状体剂量。
共有 284878 名患者接受了 448108 次头部区域 CT 检查。大多数患者（72%）仅记录了一次头部区域检查。一小部分（约 1%，n=2494）接受了≥10 次检查，而 0.1%（n=387）接受了≥20 次。在 57%的常规头部检查中，晶状体包含在成像区域内。在许多情况下，这似乎是有意的，即基于协议。在其他情况下，似乎试图通过旋转机架来排除眼睛。当眼睛完全包含在检查范围内时，估计的晶状体剂量为 20-75 mGy（平均值：47 mGy），当晶状体完全排除在外时，剂量为 2-7 mGy（平均值：3.1 mGy）。潜在的累积晶状体剂量范围从约 3 mGy 到约 4700 mGy，有 2335 名患者可能接受了>500 mGy 的剂量。
大多数年轻人的累积晶状体剂量将低于 500 mGy，这意味着白内障诱发的风险可能非常小。
