Shrimpton Paul C, Jansen Jan T M, Harrison John D
Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, UK.
Br J Radiol. 2016;89(1057):20150346. doi: 10.1259/bjr.20150346. Epub 2015 Nov 6.
To investigate the impact of evolving International Commission on Radiological Protection (ICRP) recommendations concerning calculation of effective dose (E) and compare updated typical UK values for common CT examinations with previous data.
Monte Carlo simulations have provided normalized organ doses relating to 15 CT scanner models and 5 virtual reference adults. Series of representative E/dose-length product (DLP) coefficients were derived for common examinations on the separate bases of not only older stylized mathematical phantoms and voxel phantoms presently recommended by ICRP, but also the 1977, 1990 and 2007 formulations for E. Updated E/DLP coefficients were applied to typical values of DLP from the 2011 UK survey.
Changes in ICRP recommendations that have arisen from improving evidence on stochastic risk, influence values of E by up to a factor two for CT examinations of the head and neck, although differences for the trunk typically amount to ±10%. Adoption of the voxel rather than the mathematical phantoms used previously can lead to further changes in E by a few tens of percent. Updated typical values of E for UK CT examinations range from 2 to 20 mSv. Increases by 20-400% since 2003 arise not only from increases by 30-160% in typical values of DLP, but also increases by 30-90% in relation to E/DLP coefficients for examinations of the trunk.
Values of E, including updated typical data for UK CT, should be compared with caution in relation to their purpose and underlying factors concerning their calculation.
Updated E/DLP coefficients and typical values of E for UK CT, and an appreciation of factors influencing these data.
探讨国际放射防护委员会（ICRP）关于有效剂量（E）计算的不断演变的建议所产生的影响，并将英国常见CT检查的最新典型值与先前数据进行比较。
蒙特卡罗模拟提供了与15种CT扫描仪模型和5种虚拟参考成人相关的归一化器官剂量。不仅基于ICRP目前推荐的较旧的程式化数学体模和体素体模，还基于1977年、1990年和2007年的E公式，为常见检查得出了一系列代表性的E/剂量长度乘积（DLP）系数。将更新后的E/DLP系数应用于2011年英国调查的DLP典型值。
ICRP建议的变化源于对随机风险证据的改进，对头颈部CT检查的E值影响高达两倍，尽管躯干检查的差异通常为±10%。采用体素体模而非先前使用的数学体模可导致E值进一步变化几十%。英国CT检查的E的更新典型值范围为2至20 mSv。自2003年以来增加20 - 400%，不仅是因为DLP典型值增加30 - 160%，还因为躯干检查的E/DLP系数增加30 - 90%。
应谨慎比较E值，包括英国CT的更新典型数据，考虑其目的以及计算所依据的因素。
英国CT的更新E/DLP系数和E典型值，以及对影响这些数据的因素的认识。
