2007年全国染色体畸变分析估算辐射生物剂量比对

目的 了解全国辐射生物剂量工作的现状,拟定提高全国生物剂量估算技术水平的措施。方法 在同一实验室进行照射的染色体标本制备后发放至13个自愿参加比对的单位,采用盲法对2个不同标本各分析200个和400个中期分裂相中的双着丝粒+着丝粒环(dic+r)畸变,其中7个单位进行生物剂量估算。结果 每个单位分析200或400中期分裂相的dic+r畸变率变化不大,不同单位之间有较大差异(P<0.05);同一单位的不同人员的分析结果是有所差别的(P<0.05)。大部分单位的dic+r畸变率在总dic+r畸变率平均值95%可信区间内。各估算剂量单位所估算的剂量与总体估算剂量范围95%可信区间比较,均是上限值高或高于可信区间上限。结论 为了提高全国辐射生物剂量估算水平,充分利用全国现有资源应对核突发事件,有必要采取相应的有效措施。     

2015年重庆市生物剂量盲样考核结果分析

目的 为进一步提高放射卫生技术机构染色体非稳定性畸变的分析能力和水平,保障对受照者生物剂量的评估质量。方法 中国疾病预防控制中心辐射安全所按照能力考核方案对其实验及其结果进行分析。结果 两个样品的估算剂量的相对偏差均小于20%,考核结果均为合格。结论 本单位生物剂量实验室的整体技术水平符合国家有关标准要求。     

Calyculin A诱导早熟染色体与低剂量电离辐射剂量-效应关系

目的 探讨CalyculinA诱导早熟染色体凝集技术作为低剂量电离辐射生物剂量计的可行性。方法 取健康成年人的抗凝外周静脉血,用X射线分别以0、0.1、0.25、0.5、0.75和1.0Gy照射。照射后将血样接种于RPMI1640培养基中,于37℃、5% CO₂恒温培养箱内培养48h,当培养24h时加入秋水仙素,终止培养前2h加入CalyculinA诱导早熟凝集染色体,收获制片并用Giemsa染液染色,观察G1、G2/M-PCC细胞中总畸变率、断片率、双着丝粒体加着丝粒环率与辐射剂量的效应关系。结果 用CalyculinA可成功诱导人外周血淋巴细胞产生PCC,且总畸变率、断片率、双着丝粒体加着丝粒环率随照射剂量的增加而增加,最佳拟合曲线为二次多项式模式。结论 CalyculinA诱导PCC技术可以作为一种方法来估算低剂量受照者的辐射剂量,但是需要更多的资料来完善。     

医用X射线对人体染色体畸变的影响分析

目的 了解长期低剂量电离辐射对放射工作人员染色体畸变的影响,探讨低剂量电离辐射对人体染色体畸变的敏感效应指标。方法 染色体培养采用微量全血染色体培养法。结果 染色体畸变类型放射组双着丝粒体、片断、染色体型畸变、染色体型断裂、染色体型畸变细胞率分别是对照组的6.3、2.1、3.0、3.4、2.6倍,其差别有显著及非常显著的意义。结论 长期低剂量电离辐射对放射工作人员染色体畸变有一定影响;双着丝粒体是低水平辐射损伤的良好效应指标。     

2017年度参加全国生物剂量估算能力考核结果分析

目的 通过对2017年参加全国生物剂量估算能力考核总结分析,提高该项工作的专业技术能力。方法 根据《2017年度生物剂量估算能力考核方案》,进行受照后的培养、制片、分析染色体的非稳定性畸变,统计染色体非稳定性畸变数量（dic+r）,应用国家标准上的曲线Y=7.3512×10^-3+3.4037×10^-2D+8.0398×10^-2 D²估算剂量。结果 样本05-1平均值是3.62Gy,95%的可信区间是（3.32~3.90）Gy,相对偏差为0.56%;样本05-2平均值是2.37 Gy,95%的可信区间是（2.19~2.54）Gy,相对偏差为7.73%,两样品相对偏差均<20%,综合判定本实验室生物剂量能力估算结果为合格。结论 本实验室能满足生物剂量工作需要,但仍然需要加强质量控制,规范操作,不断总结分析,建立本实验室生物剂量曲线,减少系统误差,使结果更加准确可靠,为核与辐射事故的临床救治及监督管理提供科学依据。     

一起急性外照射事件的调查与处理

目的 为确定放射事故的程度和处理方案,指导类似事故的控制和处理。方法 通过对某公司密封源脱落事故的调查,并按GBZ113-2002、GBZ151-2002二原则进行分析,估算受照剂量。结果 该脱源事故造成急性外照射的物理估算剂量为0.01 Gy,生物估算剂量在0.1 Gy以下。结论 综合物理估算剂量、生物估算剂量及临床症状及实验室检查结果,该事件为放射事件。     

核型自动扫描系统在淋巴细胞染色体畸变检测中的价值

目的 探讨核型自动扫描成像系统在淋巴细胞染色体畸变检测中的优点。方法 以192名医疗单位的放射工作人员为研究对象,分别用核型自动扫描系统检测法和人工双盲检测法对其外周血淋巴细胞染色体畸变细胞率和染色体畸变率进行检测分析。结果 对同一批标本阅片,扫描组平均用时（15.3 ±0.69） min小于人工组（42.0 ±0.56） min,差异有统计学意义（P < 0.05）。对同一批标本,扫描组的染色体畸变细胞率（0.193%）和染色体畸变率（0.227%）均高于人工组（0.065%,0.102%,）,差异均有统计学意义（P < 0.05）。结论 核型自动扫描系统可以提高淋巴细胞染色体畸变的检出率,提高阅片的速度,缩短发报告的周期,减轻实验室人员的工作量,适合标本量较多的单位使用。     

ISO 13528稳健分析法对生物剂量估算能力考核结果的评估

目的 采用ISO 13528稳健分析法对全国43家放射卫生技术机构生物剂量估算能力考核结果进行分析,评估和判断放射卫生技术机构生物剂量估算能力和水平。方法 按照4个不同照射剂量分组,每个参加机构随机抽取2个盲样,进行制片、分析及估算照射剂量,在规定时间内提交结果。根据z比分数公式对43家机构生物剂量估算结果进行分析,|z| ≤ 2即为合格。结果 4个剂量组的|z| ≤ 2的比例分别为1.7 Gy （95.7%）、2.1 Gy （91.3%）、2.8 Gy （81.8%）和3.7 Gy（90%）,在43家机构中两个考核样本均为|z| ≤ 2的有36家（83.7%）。结论 ISO 13528稳健统计可用于生物剂量估算能力考核结果分析。大多数机构的生物剂量估算能力合格,说明全国生物剂量估算能力整体水平较好,少部分机构的能力有待提高。     

儿童CT扫描有效剂量估算

目的 了解儿童CT检查有效剂量水平,为儿童CT扫描辐射危险评价提供依据。方法 通过测量CT剂量指数,计算得到剂量长度乘积(DLP),利用DLP与有效剂量E之间的相关性、线性关系及儿童相对于成人的归一化系数,估算儿童CT检查不同扫描部位的有效剂量。结果 儿童CT扫描有效剂量已达到年自然本底辐射水平。结论 对于儿童辐射危险度的评价,有效剂量存在一定的局限性。     

两种不同包装的粉末剂量计实验测量结果

目的 明确本实验室用不同包装的LiF(Mg,Cu,P)粉末对测量结果的影响。方法 用实验室试验及放射工作人员现场佩戴检测这两种不同的实验方法来验证。结果 两种包装实验结果没有明显差异。结论 本实验室开发的自动粉末包装机的袋状包装替代传统的手工管状包装可满足测量要求。     

Validation of QuickScan dicentric chromosome analysis for high throughput radiation biological dosimetry

Currently, the dicentric chromosome assay (DCA) is used to estimate radiation doses to individuals following accidental radiological and nuclear overexposures when traditional dosimetry methods are not available. While being an exceptionally sensitive method for estimating doses by radiation, conventional DCA is time-intensive and requires highly trained expertise for analysis. For this reason, in a mass casualty situation, triage-quality conventional DCA struggles to provide dose estimations in a timely manner for triage purposes. In Canada, a new scoring technique, termed DCA QuickScan, has been devised to increase the throughput of this assay. DCA QuickScan uses traditional DCA sample preparation methods while adapting a rapid scoring approach. In this study, both conventional and QuickScan methods of scoring the DCA assay were compared for accuracy and sensitivity. Dose response curves were completed on four different donors based on the analysis of 1,000 metaphases or 200 events at eight to nine dose points by eight different scorers across two laboratories. Statistical analysis was performed on the data to compare the two methods within and across the laboratories and to test their respective sensitivities for dose estimation. This study demonstrated that QuickScan is statistically similar to conventional DCA analysis and is capable of producing dose estimates as low as 0.1 Gy but up to six times faster. Therefore, DCA QuickScan analysis can be used as a sensitive and accurate method for scoring samples for radiological biodosimetry in mass casualty situations or where faster dose assessment is required.     

Cytogenetic biodosimetry for Fukushima travelers after the nuclear power plant accident: no evidence of enhanced yield of dicentrics

Individuals who traveled to contaminated areas after the Fukushima nuclear accident have concerns about the health effects. However, medical follow-up for any adverse health effects will be difficult without personal dose measurements. Cytogenetic biodosimetry is a reasonable method of assessing absorbed doses retrospectively. We analyzed dicentric chromosomes for 265 Fukushima travelers, mostly journalists and rescue workers, who had been dispatched to northeastern Japan during the nuclear emergency. As a control group, 37 healthy volunteers who had not visited Japan since the accident were enrolled. Yields of dicentrics and absorbed doses calculated from a dose-response calibration curve for travelers and the control group were compared. The cut-off level for dicentric chromosomes in the controls was 3.5 per 1000 cells. Of the 265 travelers, 31 had elevated numbers of dicentrics (High-Dics group) while 234 were below the cut-off (Normal-Dics group). All but one of the individuals in the High-Dics group also reported a significantly higher number of medical exposures to radiation within the past three years compared with the Normal-Dics or control groups. The 225 travelers with no history of medical exposure showed no difference of dicentrics yield compared to the control group. Our data indicate that Fukushima travel alone did not enhance the yield of dicentrics.     

Retrospective biodosimetry using translocation frequency in a stable cell of occupationally exposed to ionizing radiation

Two cases of hematological malignancies were reported in an industrial radiography company over a year, which were reasonably suspected of being consequences of prolonged exposure to ionizing radiation because of the higher incidence than expected in the general population. We analyzed chromosomal aberrations in the peripheral blood lymphocytes from the other workers who had been working under similar circumstances as the patients in the company. Among the subjects tested, 10 workers who belonged to the highest band were followed up periodically for 1.5 years since the first analysis. The aim of this study was to clarify pertinence of translocation analysis to an industrial set-up where chronic exposure was commonly expected. To be a useful tool for a retrospective biodosimetry, the aberrations need to be persistent for a decade or longer. Therefore we calculated the decline rates and half-lives of frequency for both a reciprocal translocation and a dicentric chromosome and compared them. In this study, while the frequency of reciprocal translocations was maintained at the initial level, dicentric chromosomes were decreased to 46.9% (31.0–76.5) of the initial frequency over the follow-up period. Our results support the long-term stability of reciprocal translocation through the cell cycle and validate the usefulness of translocation analysis as a retrospective biodosimetry for cases of occupational exposure.     

Early-response biological dosimetry--recommended countermeasure enhancements for mass-casualty radiological incidents and terrorism

The effective medical management of a suspected acute radiation overexposure incident necessitates recording dynamic medical data, measuring appropriate radiation bioassays, and estimating dose from dosimeters and radioactivity assessments in order to provide diagnostic information to the treating physician and a dose assessment for personnel radiation protection records. The accepted generic multiparameter and early-response approach includes measuring radioactivity and monitoring the exposed individual; observing and recording prodromal signs/symptoms and erythema; obtaining complete blood counts with white blood cell differential; sampling blood for the chromosome-aberration cytogenetic bioassay using the "gold standard" dicentric assay (translocation assay for long times after exposure) for dose assessment; bioassay sampling, if appropriate, to determine radioactivity contamination; and using other available dosimetry approaches. In the event of a radiological mass-casualty incident, current national resources need to be enhanced to provide suitable dose assessment and medical triage and diagnoses. This capability should be broadly based and include stockpiling reagents and devices; establishing deployable (i.e., hematology and biodosimetry) laboratories and reference (i.e., cytogenetic biodosimetry, radiation bioassay) laboratories; networking qualified reference radioactivity-counting bioassay laboratories, cytogenetic biodosimetry, and deployable hematology laboratories with the medical responder community and national radiation protection program; and researching efforts to identify novel radiation biomarkers and develop applied biological dosimetry assays monitored with clinical, deployable, and hand-held analytical systems. These research and applied science efforts should ultimately contribute towards approved, regulated biodosimetry devices or diagnostic tests integrated into a national radioprotection program.     

Novel biodosimetry methods applied to victims of the Goiania accident

Two biodosimetric methods under development at the Lawrence Livermore National Laboratory were applied to five persons accidentally exposed to a 137Cs source in Goiania, Brazil. The methods used were somatic "null" mutations at the glycophorin A locus detected as missing proteins on the surface of blood erythrocytes and chromosome translocations in blood lymphocytes detected using fluorescence in-situ hybridization. Biodosimetric results obtained approximately 1 y after the accident using these new and largely unvalidated methods are in general agreement with results obtained immediately after the accident using dicentric chromosome aberrations. Additional follow-up of Goiania accident victims will 1) help provide the information needed to validate these new methods for use in biodosimetry and 2) provide independent estimates of dose.     

采用儿童仿真模体研究胸部DR不同千伏照射下的有效剂量

目的 采用1岁儿童仿真模体计算胸部数字化摄影（DR）不同千伏条件下儿童各组织、器官的吸收剂量，估算并比较不同千伏下有效剂量。方法 塑料管分装的热释光剂量计（TLD）布放入儿童模体预留的插孔，在60、 70、80和90 kV时，自动曝光控制（AEC）模式下各曝光20次，然后回收TLD，回实验室测量。计算出不同千伏下组织、器官的吸收剂量，并分别估算出受照儿童模体全身有效剂量。结果 在60、70、80和90 kV时照射野范围内各组织、器官随千伏的增高吸收剂量逐渐降低。4个实验组中有效剂量分别为0.43、0.34、0.29和0.23 μSv。结论 儿童模体胸部摄影使用较高千伏可减少组织、器官的吸收剂量和全身有效剂量。     

驻波加速器拓频自动频率控制系统设计

目的 设计一套驻波加速器拓频自动频率控制系统,以达到消除自动频率控制系统失效因素的目的。方法 通过对自动频率控制系统协调微波源与加速管工作状态分析,调整磁控管频率、增加一个剂量变量,启动一般微波锁相自动频率控制系统。结果 消除阳极电压变化的多值性,设计出驻波加速器拓频自动频率控制系统。结论 依照该理论分析,设计出的控制系统通过在试验设备上运行,均能在较大范围的温度和脉冲调制输出脉动时稳定和可靠的工作,取得很好的效果。     

PET/CT中CT自动管电流调制模式下受检者有效剂量的研究

目的 研究PET/CT中CT自动管电流模式下受检者有效剂量与管电流阈值及噪声指数的关系,为确定最优化采集条件提供理论基础。方法 选用GE Discovery ST-16型和Discovery Elite型PET/CT,使用RS-550型仿真人体模型获得PET/CT中CT所致受检者有效剂量。两机型采用相同采集条件,即管电压120 kV,螺距为1.375,转速0.8 s/转,噪声指数（NI）8-30,间隔为2,自动管电流低限均为30 mA,高限为200~350mA,间隔为50 mA。模拟临床PET/CT的头颈部和体部分段扫描方式对仿真人体模型进行扫描。记录各种采集条件下剂量长度乘积（DLP）,计算有效剂量（ED_CT）。结果 采用相同采集条件,CT扫描所致有效剂量随噪声指数增大而降低,且曲线随自动管电流高限的增加而陡峭;Discovery Elite型扫描CT所致受检者全身有效剂量低于Discovery ST-16型。结论 对确定的受检者,PET/CT中CT所致有效剂量随扫描条件不同有较大差异。可以根据不同临床需求,选择最优化采集方案,从而尽可能降低受检者的有效剂量。     

2016—2018年成都地区部分放射从业人员个人剂量监测异常结果分析

目的 对2016—2018年成都地区部分放射从业人员个人剂量监测异常结果进行分析,以采取相应措施避免同类异常情况。方法 采用热释光测量法监测个人剂量,采用SPSS19.0统计软件对监测结果进行分析。结果 2016—2018年异常剂量人次数基本持平,不同年份异常剂量人次差异无统计学意义（P > 0.05）;从事诊断放射学的人员个人剂量异常人次最多,占75.96%;个人剂量异常原因居首位的是“个人剂量计曾经被留置于放射工作场所内”,占32.61%。结论 应进一步加强剂量计规范佩戴管理。