Kim K P, Berrington de González A, Pearce M S, Salotti J A, Parker L, McHugh K, Craft A W, Lee C
Department of Nuclear Engineering, Kyung Hee University, Gyeonggi-do, Republic of Korea.
Radiat Prot Dosimetry. 2012 Jul;150(4):415-26. doi: 10.1093/rpd/ncr429. Epub 2012 Jan 6.
Despite great potential benefits, there are concerns about the possible harm from medical imaging including the risk of radiation-related cancer. There are particular concerns about computed tomography (CT) scans in children because both radiation dose and sensitivity to radiation for children are typically higher than for adults undergoing equivalent procedures. As direct empirical data on the cancer risks from CT scans are lacking, the authors are conducting a retrospective cohort study of over 240,000 children in the UK who underwent CT scans. The main objective of the study is to quantify the magnitude of the cancer risk in relation to the radiation dose from CT scans. In this paper, the methods used to estimate typical organ-specific doses delivered by CT scans to children are described. An organ dose database from Monte Carlo radiation transport-based computer simulations using a series of computational human phantoms from newborn to adults for both male and female was established. Organ doses vary with patient size and sex, examination types and CT technical settings. Therefore, information on patient age, sex and examination type from electronic radiology information systems and technical settings obtained from two national surveys in the UK were used to estimate radiation dose. Absorbed doses to the brain, thyroid, breast and red bone marrow were calculated for reference male and female individuals with the ages of newborns, 1, 5, 10, 15 and 20 y for a total of 17 different scan types in the pre- and post-2001 time periods. In general, estimated organ doses were slightly higher for females than males which might be attributed to the smaller body size of the females. The younger children received higher doses in pre-2001 period when adult CT settings were typically used for children. Paediatric-specific adjustments were assumed to be used more frequently after 2001, since then radiation doses to children have often been smaller than those to adults. The database here is the first detailed organ-specific paediatric CT scan database for the UK. As well as forming the basis for the UK study, the results and description of the methods will also serve as a key resource for paediatric CT scan studies currently underway in other countries.
尽管医学成像有巨大的潜在益处，但人们也担心其可能带来的危害，包括与辐射相关的癌症风险。对于儿童的计算机断层扫描（CT）尤其令人担忧，因为儿童的辐射剂量和对辐射的敏感度通常高于接受同等检查的成年人。由于缺乏关于CT扫描致癌风险的直接实证数据，作者正在对英国超过24万名接受过CT扫描的儿童进行一项回顾性队列研究。该研究的主要目的是量化与CT扫描辐射剂量相关的癌症风险程度。在本文中，描述了用于估计CT扫描给儿童带来的典型器官特异性剂量的方法。利用基于蒙特卡洛辐射传输的计算机模拟，建立了一个器官剂量数据库，该模拟使用了一系列从新生儿到成年人的男女计算人体模型。器官剂量随患者体型、性别、检查类型和CT技术设置而变化。因此，利用电子放射信息系统中患者年龄、性别和检查类型的信息以及从英国两项全国性调查中获得的技术设置来估计辐射剂量。计算了2001年前后共17种不同扫描类型的新生儿、1岁、5岁、10岁、15岁和20岁的参考男性和女性个体的脑、甲状腺、乳腺和红骨髓的吸收剂量。一般来说，女性的估计器官剂量略高于男性，这可能归因于女性体型较小。在2001年之前，当通常将成人CT设置用于儿童时，年幼儿童接受的剂量更高。假设2001年之后更频繁地使用了针对儿科的调整，从那时起儿童的辐射剂量通常低于成人。这里的数据库是英国首个详细的器官特异性儿科CT扫描数据库。除了构成英国这项研究的基础外，这些结果和方法描述也将成为其他国家目前正在进行的儿科CT扫描研究的关键资源。
