我国人群辐射致胃癌危险系数估算研究

目的 估算我国人群胃癌辐射致癌危险系数.方法 应用美国电离辐射效应委员会研发的日本原子弹爆炸幸存者胃癌辐射致癌危险模型,估算其辐射致癌超额相对危险和绝对危险系数.综合日本人群辐射致癌危险转移为美国人群危险的多种转移方法,确定由日本人群向我国人群危险转移模型为相乘相加混合模型(算数尺度下,相乘和相加模型权重分别为0.7和0.3).根据我国肿瘤登记年报胃癌基线发病率,利用曲线拟合方法,估算其性别-年龄别基线发病率.综合日本人群胃癌辐射致癌危险系数及我国人群胃癌基线发病率,结合适用于我国人群的危险转移方法,估算我国人群胃癌辐射致癌危险系数.结果 估算获得我国人群胃癌辐射致癌超额相对危险系数值,男性为0.26/Sv,女性为0.64/Sv(30岁受照,60岁患癌).受照年龄越小,患癌年龄越小此系数越大.结论 我国人群胃癌辐射致癌危险系数高于日本原子弹爆炸幸存者,二者随性别-年龄变化趋势相同.     

辐射致癌危险预测模型的改进

对辐射致癌危险度的计算,是基于特定肿瘤的危险预测模型。最近,对原有模型中使用的一些参数进行了改进,包括采用两种危险系数即死亡率危险系数和发病率危险系数、提出年龄和性别特异性的致癌危险系数等。应用这些改进的危险系数,计算并给出了不同核素和不同暴露方式下组织和器官的辐射致癌危险度估计值。     

辐射致癌危险预测模型的改进

对辐射致癌危险度的计算，足基于特定肿瘤的危险预测模型。最近，对原有模型中使用的一些参数进行了改进，包括采用两种危险系数即死亡率危险系数和发病率危险系数、提出年龄和性别特异性的致癌危险系数等，应用这些改进的危险系数，计算并给出了不同核素和不同暴露方式下组织和器官的辐射致癌危险度估计值。     

辐射致癌病因概率的计算方法及其应用的进展

辐射致癌病因概率（ＰＣ）是致癌病因中归因于辐射的份额,得自辐射引起某种癌症的超额相对危险与全部相对危险的比值ＥＲＲ／（１＋ＥＲＲ）。ＰＣ概念的出现是为了解决辐射致癌的职业赔偿,为此１９８５年美国国立卫生研究院（ＮＩＨ）编制了计算ＰＣ的放射流行病学表,...     

可用于辐射致癌病因概率计算的癌症种类的思考

辐射致癌病因概率（probability of causation，PC）是指照射组某一个人所患某一类型的癌症可以归因于其接受的电离辐射（以下简称辐射）照射的可能性或似然性的估计值，它属于概率论病因的判断方法，定义为辐射导致的癌症危险与辐射危险及基线危险之和的比值。     

辐射致癌危险评估的现状、问题及展望

辐射致癌危险评估的现状、问题及展望吴德昌辐射危害的评估中起主导作用的是有关辐射致癌的危险估计，本文将仅就辐射致癌危险的现状、存在问题及未来展望提出些分析。现状自１９７７年基本建议书发表以来的数年中，出现了一些有关辐射在人群中诱发癌症危险的新资料，并获...     

辐射致癌危险模型及人群危险转移研究概况

对日本原子弹爆炸幸存者队列的流行病学研究,是各国进行辐射危害评价及赔偿的主要依据。依据流行病学数据建立模型,定量计算辐射危险,使该结果的应用更加明确。近年来随着日本原子弹爆炸幸存者队列数据资料的进一步搜集、方法学的不断完善,模型的研究也取得了新的进展。该文对迄今为止各个主要致力于辐射致癌研究的机构给出的辐射致癌模型及人群危险转移进行综述,简要介绍建立模型及转移时考虑的因素,以期为我国辐射致癌赔偿相关应用提供参照。     

辐射致白血病危险从日本人群向中国人群的转移探讨

目的 通过日本原爆人群的辐射致白血病危险估算中国人群白血病的超额相对危险(ERR)值,探讨合适的人群危险转移方法.方法 危险计算使用BEIR Ⅶ 辐射致癌计算模型及人群危险转移模型,中国人群率采用《2012中国肿瘤登记年报》中2009年中国肿瘤基线发病率.通过不同国家人群率的比较,来调整权重系数.结果 得到经人群转移后的中国人群白血病ERR值;对中国人群男性拟定相加模型权重系数为0.2、相乘模型为0.8,对女性相加模型权重系数为0.15、相乘模型为0.85.结论 在辐射致白血病危险人群转移中从总体考虑调整权重系数,得到适于估算中国人群辐射致白血病危险的人群ERR值.应用新的中国人群发病率将辐射致白血病危险直接从日本人群转移到中国人群,得出适于中国人群的辐射致白血病危险的转移方法.     

中国医用诊断X射线工作者恶性肿瘤的危险评价

辐射致癌危险评价,特别是小剂量电离辐射致癌危险的评价是当前人们最为关心的公共卫生问题之一,它不仅关系着辐射防护标准的制定,也关系着核能、放射性核素和放射源的开发和利用。为了观察和评价小剂量电离辐射对人类的致癌危害,自１９８１年以来“我国医用诊断Ｘ射线...     

生物剂量学技术在放射流行病学中的应用

低剂量电离辐射致癌危害的流行病学研究遇到了很大的困难，以研究电离辐射与生物效应定量关系主核心的放射生物剂量学与相关技术可望对流行病的剂量重建，辐射致癌危险估算，生物学模型建立和危险预测有人群中癌易感性和辐射致癌敏感性检测等提供帮助，两者的结合将把放射流行病学推向分子放射流行病学的新阶段。     

Does collimation affect patient dose in antero-posterior thoraco-lumbar spine?

IntroductionThe purpose of this study is to determine the effect of collimation on the lifetime attributable risk (LAR) of cancer incidence in all body organs (effective risk) in patients undergoing antero-posterior (AP) examinations of the spine. This is of particular importance for patients suffering from scoliosis as in their case regular repeat examinations are required and also because such patients are usually young and more susceptible to the effects of ionising radiation than are older patients.MethodsHigh sensitivity thermo-luminescent dosimeters (TLDs) were used to measure radiation dose to all organs of an adult male dosimetry phantom, positioned for an AP projection of the thoraco-lumbar spine. Exposures were made, first applying tight collimation and then subsequently with loose collimation, using the same acquisition factors. In each case, the individual TLDs were measured to determine the local absorbed dose and those representing each organ averaged to calculate organ dose.This information was then used to calculate the effective risk of cancer incidence for each decade of life from 20 to 80, and to compare the likelihood of cancer incidence when using tight and loose collimation.ResultsThe calculated figures for effective risk of cancer incidence suggest that the risk when using loose collimation compared to the use of tight collimation is over three times as high and this is the case across all age decades from 20 to 80.ConclusionTight collimation can greatly reduce radiation dose and risk of cancer incidence. However collimation in scoliotic patients can be necessarily limited.     

Risk factors for induction of breast cancer by X-rays and their implications for breast screening

In order to discuss the balance of benefit and radiation risk in a breast screening programme, it is necessary to have numerical values for the probability of breast cancer induction by X-rays, stratified by age. Various sets of such values have been used hitherto, mainly in relation to breast screening in the UK, both within the NHS Screening Programme and more generally for younger age groups. Further sets have recently been reported. These different sets of values are described and discussed, together with the effects of using additive or relative risk models, and the effect of using a dose and dose rate modifying factor (DDREF). Possible new radiation risk factors for breast cancer induction by X-rays, drawn from these sets, are identified. These are used to calculate fresh values of cancer detection/induction ratios, as an index of benefit/risk, for screening age women and for younger women with and without a family history of breast cancer.     

Evaluation of cumulative effective dose and cancer risk from repetitive full spine imaging using EOS system: Impact to adolescent patients of different populations

ObjectiveTo evaluate the effective dose and associated cancer risk using EOS system for scoliotic adolescent patients undergoing full spine imaging at different age of exposure; to demonstrate EOS system capable of delivering less radiation dose and hence of reducing cancer risk induction when compared with conventional digital X-ray systems; to obtain cumulative effective dose and cancer risk for both genders scoliotic adolescence of US and Hong Kong population.MethodsOrgan absorbed doses of full spine exposed scoliotic adolescent patients using EOS system have been simulated with the use of patient imaging parameters input to the Monte Carlo software PCXMC. Gender 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 were estimated for scoliotic patients exposed repetitively during their follow up period at different adolescent age for US and Hong Kong population.ResultsThe effective dose of full spine imaging with posteroanterior and lateral projection for patients exposed at the age between 10–18 years using the EOS system low dose protocol was calculated between 86 and 140 μSv. The corresponding LAR for US and Hong Kong population was ranged between 0.81 × 10⁻⁶ and 6.00 × 10⁻⁶. 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.ConclusionWith the use of computer simulation and analytic formulation, we obtained the cumulative effective dose and cancer risk at any age of exposure for adolescent patients of US and Hong Kong population undergoing repetitive full spine imaging using the EOS system. Female scoliotic patients would be at a statistically significant higher effective dose and cumulative cancer risk than the male patients undergoing the same EOS full spine imaging protocol.     

X射线探伤临时作业与公众安全性

目的 估算阳江高本底辐射慢性照射可能导致的实体癌超额相对危险。方法 基于自然村室内、外环境剂量和性别年龄别居留因子，估算研究群组每一个成员的累积剂量。假定剂量与癌症危险间存在线性关系，利用1979－1995年的癌症死亡率资料，按照Poisson模型计算超额相对危险。结果 全部实体癌超额相对危险（ERR）为－0．11（95％CI，－0．67，0．69）／Sv。肝癌、鼻咽癌、肺癌和胃癌等前4位癌症的ERR（95％CI）／Sv分别为－0.99(-1.60,0.10),0.10(-1.21,3.28),-0.68(-1.58,1.66)和-0.27(-1.37,2.69)。结论 未发现实体癌超额相对危险与剂量有关。     

Bestimmung von Organdosen und effektiven Dosen in der Radioonkologie

BACKGROUND AND PURPOSE: With an increasing chance of success in radiooncology, it is necessary to estimate the risk from radiation scatter to areas outside the target volume. The cancer risk from a radiation treatment can be estimated from the organ doses, allowing a somewhat limited effective dose to be estimated and compared. MATERIAL AND METHODS: The doses of the radiation-sensitive organs outside the target volume can be estimated with the aid of the PC program PERIDOSE developed by van der Giessen. The effective doses are determined according to the concept of ICRP, whereby the target volume and the associated organs related to it are not taken into consideration. RESULTS: Organ doses outside the target volume are generally < 1% of the dose in the target volume. In some cases, however, they can be as high as 3%. The effective doses during radiotherapy are between 60 and 900 mSv, depending upon the specific target volume, the applied treatment technique, and the given dose in the ICRU point. CONCLUSION: For the estimation of the radiation risk, organ doses in radiooncology can be calculated with the aid of the PC program PERIDOSE. While evaluating the radiation risk after ICRP, for the calculation of the effective dose, the advanced age of many patients has to be considered to prevent that, e.g., the high gonad doses do not overestimate the effective dose.     

Overview of Radiation-induced Skin Cancer in Humans

Summary

There are about a dozen studies of the incidence of skin cancer among irradiated populations with known skin doses that are available for estimating the risk of radiation-induced skin cancer. It is of note that they provide no evidence for a dose threshold and are compatible with a linear dose–response relationship, at least for ultraviolet radiation exposed skin. The studies also provide varying amounts of evidence concerning a number of other important issues in assessing skin cancer risk: types of skin cancer induced by ionizing radiation, the appropriateness of relative risk vs absolute risk models, combined effects of ionizing and UV radiations, and variations in sensitivity to skin cancer induction among demographic and genetic subgroups. Little epidemiological information is available on several factors, such as the RBE for high-LET radiation, the effects of dose protraction or fractionation, or variations in risk by age at irradiation. A reasonable estimate of skin cancer lethality was 0·2 per cent when weighted for the relative proportions of squamous cell and basal cell skin cancers. Average risk estimates of radiation-induced skin cancer incidence were: absolute risk (AR) of 8·5 × 10^?4 person-year-Sv and excess relative risk (RR) of 52 per cent/Sv. Lifetime skin cancer risk was calculated by life-table methods for males from exposures spread out over ages 20–60 years. The estimates for excess skin cancer incidence were 2 per cent and 11 per cent per Sv under the AR and RR models, respectively, while the corresponding mortality risks were 4 × 10^?5 and 2 × 10^?4 per Sv.     

中国阳江高本底地区居民恶性肿瘤死亡研究(1979～1998)

目的本研究旨在探索平均年有效剂量为6.4 mSv的阳江天然放射性高本底辐射的致癌危险,为小剂量电离辐射致癌危害概率估计和预测提供对人类的直接观察资料.方法癌症死亡资料收集采用前瞻性调查方法,1979～1986年的资料从动态队列中收集,1987～1998年资料从固定队列获得.两组资料通过记录连接法合并.外照射个人剂量是根据辐射剂量仪测得的环境(室内、外)辐射水平,并考虑不同性别年龄的居留因子来估算.内照射个人剂量根据各类测量数据估算,不考虑性别年龄的差异.相对危险(RR)和超额相对危险系数(ERR/Sv)及95%置信区间(CI)采用Epicure中AMFIT的程序估算.结果通过对125 079人1979～1998年的观察,共累积观察了1992940人年,期间总共死亡12 444例,其中癌症死亡1202例.整个高本底地区全癌死亡的相对危险RR=1.00(95%CI,0.89～1.14),与对照地区相比无统计学差异.高本底地区高、中、低剂量组全癌死亡相对危险的计算结果,均未显示其与对照组有统计学差异,也未发现其与剂量呈一致性的变化趋势.调查还表明,不同地域、不同观察周期以及诊断水平等因素对全癌相对危险无统计学意义的影响.部位别癌症死亡相对危险分析表明,除食管癌高本底地区高于对照地区且具有统计学意义外,其他的癌两地区均无统计学意义差异.不同剂量组部位别癌症死亡相对危险的比较分析,以及部位别癌症死亡与估算的个人终生累积内外照射剂量的剂量-效应关系分析结果,均未发现任何癌症(含食管癌)死亡与剂量的一致性变化关系,趋势检验P值均＞0.05.但高本底地区剂量范围等于或大于400 mSv剂量组的居民中,肝癌死亡明显低于0～199 mSv剂量组的居民,RR=0.31(95%CI,0.13～0.66),差异有统计学意义.全部实体癌的超额相对危险系数(ERR/Sv),在整个高本底地区估算为-0.06(95%CI,-0.60～0.67).结论高本底地区全部癌症死亡与对照地区相比无统计学意义差异,也未发现高本底地区有辐射相关的部位别癌症死亡的增加.     

Thyroid dose from common head and neck CT examinations in children: is there an excess risk for thyroid cancer induction?

This study was conducted to estimate thyroid dose and the associated risk for thyroid cancer induction from common head and neck computed tomography (CT) examinations during childhood. The Monte Carlo N-particle transport code was employed to simulate the routine CT scanning of the brain, paranasal sinuses, inner ear and neck performed on sequential and/or spiral modes. The mean thyroid dose was calculated using mathematical phantoms representing a newborn infant and children of 1year, 5 years, 10 years and 15 years old. To verify Monte Carlo results, dose measurements were carried out on physical anthropomorphic phantoms using thermoluminescent dosemeters (TLDs). The scattered dose to thyroid from head CT examinations varied from 0.6 mGy to 8.7 mGy depending upon the scanned region, the pediatric patient’s age and the acquisition mode used. Primary irradiation of the thyroid gland during CT of the neck resulted in an absorbed dose range of 15.2–52.0 mGy. The mean difference between Monte Carlo calculations and TLD measurements was 11.8%. Thyroid exposure to scattered radiation from head CT scanning is associated with a low but not negligible risk of cancer induction of 4–65 per million patients. Neck CT can result in an increased risk for development of thyroid malignancies up to 390 per million patients.