Department of Radiology, Queen Mary Hospital, Hong Kong.
Department of Radiology, Queen Mary Hospital, Hong Kong.
Eur J Radiol. 2018 Apr;101:87-91. doi: 10.1016/j.ejrad.2018.02.015. Epub 2018 Feb 13.
To evaluate and to obtain analytic formulation for the calculation of the effective dose and associated cancer risk using the EOS microdose protocol for scoliotic pediatric patients undergoing full spine imaging at different age of exposure; to demonstrate the microdose protocol capable of delivering lesser radiation dose and hence of further reducing cancer risk induction when compared with the EOS low dose protocol; to obtain cumulative effective dose and cancer risk for both genders scoliotic pediatrics of US and Hong Kong population using the microdose protocol.
Organ absorbed doses of full spine exposed scoliotic pediatric patients have been simulated with the use of EOS microdose protocol imaging parameters input to the Monte Carlo software PCXMC. Gender and age specific effective dose has been calculated with the simulated organ absorbed dose using the ICRP-103 approach. The associated radiation induced cancer risk, expressed as lifetime attributable risk (LAR), has been estimated according to the method introduced in the Biological Effects of Ionizing Radiation VII report. Values of LAR have been estimated for scoliotic patients exposed repetitively during their follow up period at different age for US and Hong Kong population.
The effective doses of full spine imaging with simultaneous posteroanterior and lateral projection for patients exposed at the age between 5 and 18 years using the EOS microdose protocol have been calculated within the range of 2.54-14.75 μSv. The corresponding LAR for US and Hong Kong population was ranged between 0.04 × 10 and 0.84 × 10. Cumulative effective dose and cancer risk during follow-up period can be estimated using the results and are of information to patients and their parents.
With the use of computer simulation and analytic formulation, we obtained the cumulative effective dose and cancer risk at any age of exposure for pediatric patients of US and Hong Kong population undergoing repetitive microdose protocol full spine imaging. Girls would be at a statistically significant higher cumulative cancer risk than boys undergoing the same microdose full spine imaging protocol and the same follow-up schedule.
评估并获得分析公式，以计算使用 EOS 微剂量方案对不同年龄段接受全脊柱成像的脊柱侧凸儿科患者的有效剂量和相关癌症风险；证明微剂量方案能够提供较小的辐射剂量，从而进一步降低与 EOS 低剂量方案相比的癌症风险诱导；使用微剂量方案为美国和香港人口的脊柱侧凸儿科患者获得累积有效剂量和癌症风险。
使用 EOS 微剂量方案成像参数输入蒙特卡罗软件 PCXMC 模拟全脊柱暴露的脊柱侧凸儿科患者的器官吸收剂量。使用 ICRP-103 方法，根据模拟器官吸收剂量计算性别和年龄特异性有效剂量。根据《电离辐射生物效应 VII 报告》中介绍的方法，估计与辐射相关的癌症风险，以终生归因风险 (LAR) 表示。已针对美国和香港人口在不同年龄接受重复暴露的脊柱侧凸患者在随访期间估计 LAR 值。
使用 EOS 微剂量方案对 5 至 18 岁患者进行前后位和侧位同时投影的全脊柱成像的有效剂量计算范围为 2.54-14.75 μSv。美国和香港人口的相应 LAR 范围为 0.04×10 至 0.84×10。可以使用结果估计随访期间的累积有效剂量和癌症风险，这对患者及其父母具有信息价值。
通过计算机模拟和分析公式，我们获得了接受重复微剂量方案全脊柱成像的美国和香港人口的儿科患者在任何暴露年龄的累积有效剂量和癌症风险。接受相同微剂量全脊柱成像方案和相同随访计划的女孩的累积癌症风险比男孩高统计学显著。
