受检者体表剂量的测量

目的 结合我国已经颁布执行的医用诊断X射线受检者体表剂量相关法规与标准,着重介绍使用RD98智能型诊断X射线剂量仪测量受检者体表剂量的方法。方法 分析医用诊断X射线受检者体表剂量的目前现状。结果 推荐使用医用诊断X射线剂量指导水平。结论 采用诊断X射线剂量仪定期监测X射线机输出量,降低受检者电离辐射剂量。     

河南省部分驻军放射工作者个人剂量监测结果分析

目的 了解和掌握河南省驻军放射工作者的职业照射剂量水平。方法 个人剂量应用热释光剂量法,定期测读。结果 共监测195人,集体剂量为403.10 mSv,人均年剂量1.27~2.43 mSv·a^-1,其中以医用诊断X射线工作者较高。结论 医用诊断X射线工作者是今后防护的重点,此外还应改善基层部队放射工作人员的工作条件。     

拉萨市医用诊断X射线工作者个人剂量监测结果分析

目的 了解拉萨市医用诊断X射线工作者的职业照射剂量水平和影响因素,为采取针对性的防护措施提供科学依据。方法 采用国家标准规定的热释光个人剂量监测方法,佩戴周期为3个月。结果 监测了拉萨市区及其辖7县共10家医院,共34名医用诊断X射线工作者,其中个人剂量结果合格人数为31人,占总人数的91%。结论 拉萨市医用诊断X射线工作者的防护仍是今后工作的重点。     

广元市医用诊断X射线工作者血清免疫水平调查

目的 调查广元市医用诊断X射线工作者血清免疫水平。方法 采用彩色免疫单向扩散法测定280名医用诊断X射线工作者(调查组)和183名正常人员(对照组)血清中IgA、IgG、IgM含量。结果 医用诊断X射线工作者血清中IgA、IgG、IgM三种免疫球蛋白含量均明显低于对照人员,差异有非常显著性(P<0.01)。结论 医用X射线工作者血清免疫水平比正常人群低,辐射生物效应明显,提示放射防护工作应进一步加强。     

医用诊断X射线工作者肿瘤流行病学调查的数据处理

目的 建立医用诊断X射线工作者肿瘤流行病学调查的数据处理程序。方法 根据《全国医用诊断X射线工作者恶性肿瘤流行病学调查》方案。结果 建立了肿瘤流行病学调查的数据库和统计分析软件。结论 所用软件能极大地提高效率获得较为可信的分析结果。     

肇庆市医用X射线诊断机卫生防护现状调查

目的 为了解、掌握肇庆市医用X射线诊断机的分布与卫生防护现状,为规范监督管理提供科学依据。方法 对全市医用X射线诊断机的分布、卫生防护与工作人员个人剂量进行调查、测定。并建立相应的技术档案,作出卫生评价。结果 市、县组医疗机构中,大容量的医用X射线诊断机卫生防护较好;镇级与部分县级医疗机构中,小容量的医用X射线诊断机卫生防护较差。工作人员个人剂量低于国家防护标准规定的限值。结论 应加强对基层医院的监督管理,确保放射工作人员受照剂量在标准限值内。     

黑龙江省1950~1995年间医用诊断X射线工作者恶性肿瘤流行病调查

目的 调查黑龙江省1950~1995年间医用诊断X射线工作者恶性肿瘤发生情况。方法 流行病学调查方法,1980年以前为回顾性调查,1980年以后每5年一次作前瞻性调查。结果 医用诊断X射线工作者恶性肿瘤发病率未见高于对照的医务人员(RR=0.94),但其中的白血病、胃癌、乳腺癌和甲状腺癌的发病率高于对照。结论 从医用诊断X射线工作者相对危险与工龄、参加工作的时期和年龄的分析可以看出,黑龙江省的医用诊断X射线工作者白血病,女性乳腺癌、甲状腺癌发病率的增加与职业照射有关。     

广东省医用X射线诊断病人的受照剂量与分析

目的 了解广东省医用X射线诊断病人的受照剂量水平。方法 按照全国"九五"期间X射线诊断医疗照射的剂量水平调查方案进行。结果 得出门诊胸透等24种常见医用X射线诊断和CT检查的平均受照剂量。结论 其均值基本可代表广东省医用X射线诊断病人的受照剂量水平。     

放射工作场所及X射线机房外环境的防护监测方法

目的 探索放射工作场所及X射线机房外环境的防护监测方法。方法 参照GBZ138-2002医用X射线诊断卫生防护监测规范等相关标准和规范文件。用FJ-347A型X、γ剂量巡测仪监测。结果 在本辖区内每年测试各类医用X射线诊断机约180台。结论 该检测方法是可行和可操作的。     

昆明市医用诊断X射线防护状况的调查

目的 了解昆明市医用诊断X射线现状以及存在的问题,为今后放射卫生管理提供依据。方法 对昆明市的医用诊断X射线机应用单位进行综合监督监测,调查昆明市医用诊断X射线的防护和基本情况、放射工作人员的个人剂量等情况。结果 昆明市近年来X射线诊断单位、设备、工作人员等均呈不断增长趋势,放射工作人员健康状况较好,医用诊断X射线机使用场所存在一些问题。结论 在促进发展医用诊断X射线技术的同时,加强监督管理,保护放射工作人员和受检者的身体健康。     

Individual biodosimetry at the natural radiation background level

The present note describes new advancements to a valued tool in retrospective biodosimetry that lower the threshold of detection of radiation dose to 29 mGy. The advanced method is based on the electron paramagnetic resonance measurements of stable radiation-induced radicals in tooth enamel. Earlier this method had been used only for reconstruction of high radiation doses obtained accidentally. New opportunity of reconstruction of doses lower than 100 mGy opens a new realm of possibilities for assessing the health effects of ionizing radiation at the natural radiation background level.     

Photon dose conversion coefficients for human teeth in standard irradiation geometries

Photon dose conversion coefficients for human tooth materials are computed in energy range from 0.01 to 10 MeV by the Monte Carlo method. The voxel phantom "Golem" of the human body with newly defined tooth region and a modified version of the EGS4 code have been used to compute the coefficients for 30 tooth cells with different locations and materials. The dose responses are calculated for cells representing buccal and lingual enamel layers. The computed coefficients demonstrate a strong dependence on energy and geometry of the radiation source and a weaker dependence on location of the enamel voxels. For isotropic and rotational radiation fields, the enamel dose does not show a significant dependence on tooth sample locations. The computed coefficients are used to convert from absorbed dose in teeth to organ dose or to integral air kerma. Examples of integral conversion factors from enamel dose to air kerma are given for several photon fluences specific for the Mayak reprocessing plant in Russia. The integral conversion factors are strongly affected by the energy and angular distributions of photon fluence, which are important characteristics of an exposure scenario for reconstruction of individual occupational doses.     

Q-band EPR biodosimetry in tooth enamel microsamples: feasibility test and comparison with x-band

A comparative study of electron paramagnetic resonance dosimetry in Q- and X-bands has shown that Q-band is able to provide accurate measurements of radiation doses even below 0.5 Gy with tooth enamel samples as small as 2 mg. The optimal amount of tooth enamel for dose measurements in Q-band was found to be 4 mg. This is less than 1% of the total amount of tooth enamel in one molar tooth. Such a small amount of tooth enamel can be harmlessly obtained in an emergency requiring after-the-fact radiation dose measurement. The other important advantage of Q-band is full resolution of the radiation-induced EPR signal from the native, background signal. This separation makes dose response measurements much easier in comparison to conventional X-band measurements in which these overlapping signals necessitate special methods for doses below 0.5 Gy. The main disadvantages of Q-band measurements are a higher level of noise and lower spectral reproducibility than in X-band. The effect of these negative factors on the precision of dose measurements in Q-band could probably be reduced by improvement of sample fixation in the resonance cavity and better optimization of signal filtration to reduce high-frequency noise.     

Dose reconstruction by EPR spectroscopy of tooth enamel: application to the population of Zaborie village exposed to high radioactive contamination after the Chernobyl accident

Individual irradiation doses were determined by electron paramagnetic resonance spectroscopy of the tooth enamel of the inhabitants of Zaborie, the most contaminated inhabited settlement not evacuated after the Chernobyl accident. Dose determination was performed using a specially developed automatic spectrum processing procedure. Spectrum processing was carried out in different operating modes, and average results were taken in order to reduce the contribution of uncertainty in dose determination caused by spectrum processing. The absorbed doses determined in enamel were corrected to take into account the contribution of natural background radiation and to determine the individual excess dose due to radioactive contamination of the territory. Individual excess doses are compared to calculated individualized doses to teeth, estimated using the local radioactive contamination levels, dose rates, and information concerning individual behavior. The individual excess doses measured by electron paramagnetic resonance spectroscopy and the calculated individualized doses are fully independent. Mean square variation between results of two methods was found to be 34 mGy, which is consistent with error estimation for both methods. This result can validate both the methodology of signal processing presented here when using electron paramagnetic resonance dosimetry of tooth enamel for low doses and the methodology of individualized dose calculation.     

变形链球菌中釉原蛋白序列在龋病预防中的矿化机理初探

目的 探讨变形链球菌中的釉原蛋白序列在龋病脱矿、矿化过程中作用及分子机理。方法 体外重组、纯化变形链球菌和正常人釉基质中的釉原蛋白功能片段,比较其结构和功能的异同,从蛋白质量、自组装形态、体外成核能力和结晶形态等方面逐一分析区别。结果 二者单体形态和大小类似（3～5 nm）,都能初级组装为纳米小球,在变形链球菌中纳米球相互重叠形成网状的纳米链,而人类样本中纳米球端端相接组合成规律的纳米链。结论 分子水平的结构差异令二者引导形成羟基磷灰石晶体质地和形态大相径庭:在变形链球菌组中杂乱无章、表面粗糙;人釉原蛋白组中规则平行排列、表面致密。此发现对龋病的病因学探讨和预防及釉质再生提出了新的切入点和思路。     

2例严重的~(60)Co放射事故受照人员的牙齿剂量估算

目的用电子自旋共振方法对山东事故中两例受照人员的3颗牙齿进行剂量估算。方法将受照人员的牙齿经过处理后得到牙釉质样品,进行ESR信号测量,将样品ESR信号的相对强度代入本实验室建立的牙釉质剂量响应曲线后,得到的3颗牙齿的吸收剂量。结果两例受照人员牙釉质ESR吸收剂量剂量分别为:受照人A的牙齿剂量为26.1~29.4Gy;受照人B的两颗牙齿剂量分别为14.9~18.3Gy,15.2~18.5Gy。结论两例受照人员牙釉质ESR剂量测量方法为大剂量照射事故剂量估算提供了一种重要的依据。     

Relation between lead in surface tooth enamel, blood, and saliva from children residing in the vicinity of a non-ferrous metal plant in Belgium.

Two groups of schoolchildren between seven and 12 years old residing in the vicinity of a non-ferrous industrial plant and exposed to lead (Pb) at a concentration that could cause health problems, were monitored. Concentrations of Pb in blood (blood-Pb), which were determined at regular six monthly intervals, were related to the Pb concentrations in surface tooth enamel (enamel-Pb). Acid etch biopsy samples of surface enamel were taken at the end of the five year study period in the first group (A) and after two years in the second group (B). Salivary Pb (saliva-Pb) concentrations were determined for the first study group on the same day that the enamel biopsies were performed. Calibration of the data was necessary--that is, blood-Pb concentration with respect to age and sex and enamel-Pb concentration with respect to etch depth and age. The blood-Pb concentrations declined with time. Surface enamel Pb concentrations correlated with blood-Pb concentration for the period starting with the pre-eruptive development of the incisors, related to blood-Pb concentration for a long time, and corresponded partly to the exposure at the time of pre-eruptive development and/or eruption. Through the correlation with enamel-Pb concentration, the seasonal behaviour of blood-Pb concentration became apparent. Saliva-Pb concentrations related to blood-Pb concentrations only in the short term.     

Relation between lead in surface tooth enamel, blood, and saliva from children residing in the vicinity of a non-ferrous metal plant in Belgium

Two groups of schoolchildren between seven and 12 years old residing in the vicinity of a non-ferrous industrial plant and exposed to lead (Pb) at a concentration that could cause health problems, were monitored. Concentrations of Pb in blood (blood-Pb), which were determined at regular six monthly intervals, were related to the Pb concentrations in surface tooth enamel (enamel-Pb). Acid etch biopsy samples of surface enamel were taken at the end of the five year study period in the first group (A) and after two years in the second group (B). Salivary Pb (saliva-Pb) concentrations were determined for the first study group on the same day that the enamel biopsies were performed. Calibration of the data was necessary--that is, blood-Pb concentration with respect to age and sex and enamel-Pb concentration with respect to etch depth and age. The blood-Pb concentrations declined with time. Surface enamel Pb concentrations correlated with blood-Pb concentration for the period starting with the pre-eruptive development of the incisors, related to blood-Pb concentration for a long time, and corresponded partly to the exposure at the time of pre-eruptive development and/or eruption. Through the correlation with enamel-Pb concentration, the seasonal behaviour of blood-Pb concentration became apparent. Saliva-Pb concentrations related to blood-Pb concentrations only in the short term.     

Comparison study of tooth enamel ESR spectra of cows,goats and humans

The ESR radiation dosimetric properties of tooth enamel samples from cows and goats were investigated and compared with those of human samples. Samples were prepared first mechanically, and then chemically. The study results showed that the native signals from cow and goat samples were weaker than those from human samples; the radiation sensitivities for cow and goat samples were very close to those of human tooth enamel samples. These results indicated that cow and goat teeth could be alternative materials for radiation dose estimation.     

Lead concentrations of enamel and dentine of deciduous teeth of children from two Finnish towns

The proton-induced x-ray emission method was used to analyze lead concentrations in enamel and dentine of deciduous teeth of 105 6- and 9-yr-old children living in two Finnish towns. Helsinki, the capital city, was assumed to represent high lead exposure and Kuopio, a country town in the middle of Finland, low or moderate lead exposure. In all but two teeth the enamel contained higher lead concentrations than dentine. The individual enamel-dentine lead concentration ratio was not stable but varied greatly. The median dentine lead concentration for 9-yr-old children in Helsinki and Kuopio was 2.0 ppm and 2.9 ppm, respectively, and for 6-yr-old children was 2.5 ppm and 2.7 ppm, respectively. The enamel lead concentrations found in 9-yr-olds in Helsinki and Kuopio were 4.2 and 4.5 ppm, and in 6-yr-olds were 9.1 and 4.4 ppm, respectively. The results reveal low or moderate lead concentrations. Nevertheless, a twofold and statistically significant (P less than .01) increase was found in the enamel of Helsinki children born in 1974 compared with those born in 1971.