南京“5.7” 192Ir源放射事故患者的生物剂量估算

目的 用3种方法估算南京"5.7" ¹⁹²Ir源放射事故患者的生物剂量,为核与辐射事故受照者的临床救治提供剂量资料。方法 受照后第5天采集患者外周血,分别进行外周血淋巴细胞染色体"双着丝粒+环"("dic+r")畸变分析、胞质分裂阻滞微核(CBMN)分析、核质桥(NPB +FHC)分析,并估算生物剂量。用双着丝粒畸变在细胞间的泊松分布情况检验照射的均匀性。结果3种方法估算的该患者受到的一次全身等效剂量分别为"dic+r"畸变分析1.51 Gy (95% CI 1.40~1.61),CBMN 分析1.47 Gy (95% CI 1.36~1.60),NPB+FHC分析1.30 Gy(95% CI 1.00~1.60)。泊松分布检验结果显示,该患者"dic+r"畸变偏离泊松分布,受到了不均匀照射。结论 外周血淋巴细胞染色体"dic+r"畸变分析、CBMN分析、NPB+FHC分析均是有效的生物剂量估算手段,对本例急性局部不均匀照射患者估算的一次全身等效剂量与临床诊断结果相符。     

河南“4．26”^60Co源辐射事故受照者的生物剂量（染色体畸变）估算

目的：用染色体畸变分析方法对河南“4．26”^60Co辐射事故7例受照者，进行了早期生物剂量估算，方法：照后4－5d取血培养，分析第一次有丝分裂细胞“双＋环”畸变率，并由此估算生物剂量，用“双＋环”畸变在细胞间的泊松分布情况，检验照射的均匀性，结果：7例受照者依据“双＋环”畸变率估算的个体辐射剂量分别为5．09Gy(梅），2.61Gy（天），2.49Gy(旺），0.89Gy/(勇），0.70Cy(民），0.58Gy（义）和0.08Gy(宇），与用物理方法测定的剂量化比较接近，亦与放射损伤的临床诊断完全吻合，泊松分布检验证实，“梅”和“旺”双＋环畸变离泊松分布，基余5例符合泊松分布，结论：染色体畸变分析是非常可靠的生物剂量估算方法。“梅”和“旺”受到不均照射，基他5例受到比较均匀的照射。     

染色体畸变率估算32P的辐射剂量

目的 应用G显带的染色体双着丝粒畸变率评估32p的辐射剂量.方法 应用4 MV的X射线对离体人血液进行0.5 Gy、1 Gy、2 Gy和4 Gy的照射,建立染色体双着丝粒畸变率和X射线的辐射剂量的剂量-效应曲线.将74 kBq的32p胶体加入淋巴细胞的培养液后72 h,进行G显带染色体分析,通过X射线的辐射剂量和染色体双着丝粒畸变率的剂量-效应曲线来评估32p的辐射剂量.结果 4 MV的X射线的辐射剂量和染色体的双着丝粒畸变率呈线性正相关,剂量-效应曲线为y=24.05x- 13.34 (R2=0.975).74 kBq的32P胶体产生的染色体双着丝粒畸变率为18％,即74 kBq的32p胶体在5 ml淋巴细胞培养液中72 h约产生1.3 Gy的辐射剂量.结论 应用染色体畸变率可以有效地评估放射性核素的内照射剂量.     

60Coγ射线超大剂量照射离体人外周血染色体畸变的剂量-效应研究

目的 探讨超大剂量γ射线离体照射后人外周血淋巴细胞染色体畸变的量效关系,建立双+环(dic+r)大剂量-效应曲线。方法 外周静脉血样采自3名健康男性,经 ⁶⁰Co γ线(0~50 Gy,剂量率2.35Gy/min)照射。采用即刻加秋水仙素的微量全血法,分别培养52、72及96h。计数有丝分裂指数(MI)、双着丝粒体(dic)和环(r)畸变数,拟合dic+r剂量-效应曲线,对2例受大剂量照射的事故患者进行剂量估算。结果 MI随照射剂量的增加而逐渐减少。每细胞dic+r频率随照射剂量增加而增加直到23Gy(5Gy之后增加幅度较前变小),＞23Gy后趋于饱和。对所获数据进行回归分析,拟合dic+r大剂量-效应曲线(5~23Gy):每细胞dic+r频率y=-1.608(±0.300)+0.830 (±0.051)D-0.013(±0.002) D² (R²=0.998)。用拟合曲线对2例受照患者剂量的估算结果与用物理方法和电子自旋共振(ESR)法估算的剂量及临床表现基本一致。结论 本研究建立的dic+r大剂量-效应曲线, 可估计的上限剂量达23Gy,有可能提高常规染色体畸变分析用作生物剂量计的实用价值。     

一起介入治疗意外照射导致背部大面积放射性皮肤损伤患者的生物剂量估算

目的 对疑似因介入治疗致背部大面积皮肤损伤的患者进行生物剂量估算与重建。方法 术后约7个月（2020年7月22日）,采集患者外周血进行染色体畸变分析并用不同方法构建的剂量曲线估算剂量,用剂量估算的修正系数、Dolphin''s模型和Qdr方法重建患者术后短期内的受照剂量。结果 基于dic半自动与dic+r人工分析及4条剂量曲线估算患者的全身平均吸收剂量为0.68~0.95 Gy,泊松分布检验结果显示u值均>1.96,患者受到局部不均匀照射,且半自动分析可明显提高剂量估算的效率。3种重建剂量方法修正后估算患者术后短期内的全身平均吸收剂量为1.80~2.86 Gy。估算的生物剂量与该患者存在放射损伤和临床诊断为局部放射性皮肤损伤Ⅳ度的结果基本一致。结论 通过染色体畸变分析和生物剂量估算,确诊了1例因介入治疗致背部大面积放射性皮肤损伤的患者,非稳定性染色体畸变分析对局部不均匀照射受照者回顾性生物剂量的估算与重建有可行性。     

河南“4.26”~(60)Co源辐射事故受照者的生物剂量(染色体畸变)估算

目的　用染色体畸变分析方法对河南“4 2 6”6 0 Co辐射事故 7例受照者 ,进行了早期生物剂量估算。方法　照后 4～ 5d取血培养 ,分析第一次有丝分裂细胞“双 环”畸变率 ,并由此估算生物剂量。用“双 环”畸变在细胞间的泊松分布情况 ,检验照射的均匀性。结果　 7例受照者依据“双 环”畸变率估算的个体辐射剂量分别为 5 0 9Gy(梅 )、2 6 1Gy(天 )、2 49Gy(旺 )、0 89Gy(勇 )、0 70Gy(民 )、0 5 8Gy(义 )和 0 0 8Gy(宇 ) ,与用物理方法测定的剂量比较接近 ,亦与放射损伤的临床诊断完全吻合。泊松分布检验证实 ,“梅”和“旺”双 环畸变偏离泊松分布 ,其余 5例符合泊松分布。结论　染色体畸变分析是非常可靠的生物剂量估算方法。“梅”和“旺”受到不均照射 ,其他 5例受到比较均匀的照射。     

部分照射离体血对淋巴细胞染色体畸变形成的影响

目的 分析⁶⁰Coγ射线部分照射离体血对人外周血淋巴细胞染色体畸变形成的影响。方法 用2Gy⁶⁰Coγ射线37℃照射人外周血后以不同比例混合后进行培养、制片和分析染色体畸变。结果 染色体畸变随照射血比例的增加而增加,与单纯照射组相比,混合照射血的染色体畸变率高。1:1比例混合估算出的剂量为1.27Gy,大于1Gy;0.5:1比例混合估算出的剂量为0.93Gy,大于0.5Gy;而在1:0组,照射剂量与估算剂量基本一致。结论 染色体畸变可以作为估算非均匀照射的生物学指标之一。     

低剂量辐射诱导细胞遗传学适应性反应的某些规律

10mGyX射线可诱导人外周血淋巴细胞和家兔外周血淋巴细胞产生对相继较大剂量(1.5Gy)X射线诱发染色体畸变的抗性, 称之为适应性反应。在离体和整体条件下, 该反应广泛存在于体细胞和生殖细胞中, 其反应程度与低剂量辐射的剂量呈负相关, 即辑先照射的剂量愈低, 诱导的适应性反应愈明显。同时还发现该反应也受许多因素的影响, 如: 低剂量辐射的剂量、剂量率, 照射时间以及生物个体差异等因素。     

不同结构类型双着丝粒体建立的剂量-效应曲线估算剂量可行性研究

目的 探讨基于不同结构类型双着丝粒体（dicentrics,dic）建立的剂量-效应曲线估算生物剂量的可行性。方法 采集两名健康人外周血样品,用0、0.5、1、2、3、4、5和6 Gy ⁶⁰Co γ射线（剂量率为0.27 Gy/min）离体照射人外周血,常规培养、收获和制备染色体标本,镜下分析并记录不同结构类型dic;应用CABAS软件建立dic剂量-效应曲线;并对两验证样本进行剂量估算。结果 不同结构类型dic率均随受照剂量的增加而升高（R²=0.886~0.943,P<0.01）,各剂量点经典型和单端型dic构成比之和约占所有类型dic的92%以上,而近距型dic和双端型dic分别在各照射剂量点的构成比均<4%。不同结构类型dic剂量-效应曲线的R²值均达到0.998;应用4条曲线估算的受照射剂量差异无统计学意义（P>0.05）。经典型dic剂量-效应曲线估算较高剂量时（3.9 Gy）,相对偏差均≤13.08%。结论 基于不同结构类型dic建立的剂量-效应曲线具有估算生物剂量的可行性。     

染色体畸变分析用于非均匀与局部照射剂量估计的研究进展

针对ＩＡＥＡＴＲＳ－２６０报告推荐的不纯泊松分布方法与Ｑｄｒ方法的适用性，用染色体畸变分析方法进行了离体模拟实验研究，但在活体情况下的适用性尚需进一步验证。     

Comparative study of micronucleus assays and dicentric plus ring chromosomes for dose assessment in particular cases of partial-body exposure

Abstract

Purpose: The goal was to compare the micronucleus (MN) and dicentric plus ring chromosomes (D?+?R) assays for dose assessment in cases of partial body irradiations (PBI).

Materials and methods: We constructed calibration curves for each assay at doses ranging from 0 to 5?Gy of X-rays at dose rate of 0.275?Gy/min. To simulate partial-body exposures, blood samples from two donors were irradiated with 0.5, 1, 2 and 4?Gy and the ratios of irradiated to unirradiated blood were 25, 50, and 100%. Different tests were used to confirm if all samples were overdispersed or zero-inflated and for partial-body dose assessment we used the Qdr, Dolphin and Bayesian model.

Results: In our samples for D?+?R calibration curve, practically all doses agreed with Poisson assumption, but MN exhibited overdispersed and zero-inflated cellular distributions. The exact Poisson tests and zero-inflated tests demonstrate that virtually all samples of D?+?R from PBI simulation fit the Poisson distribution and were not zero-inflated, but the MN samples were also overdispersed and zero-inflated. In the partial-body estimation, when Qdr and Dolphin methods were used the D?+?R results were better than MN, but the doses estimation defined by the Bayesian methodology were more accurate than the classical methods.

Conclusions: Dicentric chromosomes continue to prove to be the best biological marker for dose assessment. However exposure scenarios of partial-body estimation, overdispersion and zero-inflation may not occur, it being a critical point not only for dose assessment, but also to confirm partial-body exposure. MN could be used as alternative assay for partial-body dose estimation, but in case of an accident without any information, the MN assay could not define whether the accident was a whole-body irradiation (WBI) or a PBI.     

Cytogenetic assessment of heterogeneous radiation doses in cancer patients treated with fractionated radiotherapy

The purpose of this study was to evaluate the in vivo dose–response relation of chromosome aberration formation and distribution in a context of localised and fractionated radiotherapy. Cytogenetic analysis was applied to eight patients, all treated for the same tumour localisation; the same localisation was used to prevent the variability usually observed between patients treated with radiotherapy and to allow the corresponding roles of the size of irradiation field and of the dose rate to be studied. The yield of dicentrics, centric rings and fragments was measured in blood samples taken before treatment, during the course of radiotherapy and up to 6 months after. After the first fraction of radiotherapy, we observed that the whole-body dose estimated from the yield of dicentrics and rings was higher (0.35±0.2 Gy) than the calculated equivalent whole-body dose (0.07±0.04 Gy). By contrast, the partial-body dose derived from the Qdr (quotient of dicentrics and rings) model was estimated to be 2.2±0.3 Gy, which agreed quite well with the dose delivered to the tumour (2.1±0.1 Gy). We also found a correlation between the yield of induced chromosome aberrations and the target field size (p = 0.014). U-value analysis showed that the distribution of dicentrics and rings was overdispersed, despite the fractionation of the exposure, and a positive correlation between the U-value and the dose rate was observed (p = 0.017). Overall, these results suggest that the proportion of undamaged lymphocytes could increase with the dose rate.Quantification of chromosome aberrations in circulating lymphocytes is conventionally used to estimate the dose received by individuals accidentally exposed to ionising radiation. The observed frequency of dicentrics and centric rings is referred to a dose–response curve established in vitro, which provides the whole-body dose [1, 2]. When irradiation is heterogeneous over different parts of the body, only some lymphocytes are exposed. Because irradiated and unirradiated lymphocytes are mixed in the blood circulation, the dose received by the irradiated lymphocytes and consequently the dose delivered locally should be underestimated. Two mathematical models, Qdr and Dolphin''s deviation from the Poisson distribution, have been developed to assess the dose according to the fraction of exposed lymphocytes [3, 4]. Both models have been validated in vitro by mixing irradiated and unirradiated blood in different proportions [5]. These approaches have also been tested in vivo in accidental situations, with promising results [6, 7]. Furthermore, recent in vivo studies of cancer patients who had received 8 Gy of radiotherapy in a single fraction have shown that the derived partial-body dose obtained with both Qdr and Dolphin methods are in agreement with the doses estimated from the radiotherapy regimens [8].Cytogenetic assessment of cancer patients undergoing fractionated therapeutic irradiation would also be useful to evaluate the impact of the treatment on the yield of chromosome aberrations and on their distribution within the lymphocyte population. This could allow the evaluation of damage induced by such treatment in the patient''s circulating lymphocytes. Several studies have examined chromosome aberrations in blood samples from patients undergoing fractionated radiotherapy. These studies, which have used conventional cytogenetics, fluorescence in situ hybridisation (FISH) or both, showed a dose-dependent increase in the yields of aberrations, but with substantial interpatient variability [9–11]. The same variability in the rate of damage induced in lymphocytes during radiotherapy has been observed in other studies that used different measurements, such as premature chromosome condensation (PCC), micronuclei or γ-H2AX foci [12–14]. Explanations for these interpatient differences have suggested that damage yields after fractionated partial-body exposure do not depend only on the dose delivered locally, but may be also influenced by many other parameters, including individual variability in the response to ionising radiation, target field size or tumour localisation [9, 10, 12]. In fact, fractionated radiotherapy is a typical example of non-uniform exposure. During a session of radiotherapy, lymphocytes from the vascular pool may receive relatively small doses whereas those from the resident pool in the field may receive higher doses; both are ultimately mixed by the circulation in the following hours [15]. Furthermore, distribution of the lymphocyte pool may vary greatly within the human body; this implies that the geometry of irradiation may have a high impact on the proportion of vascular vs resident lymphocytes that may be irradiated. To measure the impact of radiotherapy treatment parameters on the aberration yields induced in peripheral lymphocytes, it is useful to study patients who have tumours in the same anatomical region. Therefore, to analyse the roles of the target field size and the dose rate relating to interpatient variability, we applied conventional cytogenetic methods to eight patients receiving fractionated radiotherapy for head and neck cancer. This anatomical region contains a high number of blood vessels and also a high number of lymph nodes. We evaluated the relation between the yield of dicentrics and centric rings measured in lymphocytes and the radiotherapy field size. We compared the dose estimate using cytogenetic methods with the physical doses obtained using calculations. Finally, we verified whether the test for deviation from Poisson distribution was able to detect the heterogeneity of the exposure after several fractions of radiotherapy.     

CB微核法在忻州事故生物剂量估算中的应用

本文作者报道了在忻州放射事故中３４例受检者ＣＢ法微核的检测结果。同时，用本实验室建立的ＣＢ微核剂量效应曲线对上述受检者进行生物剂量估算，并与染色体畸变分析估算的剂量进行比较，结果两种方法估算的剂量基本一致。表明ＣＢ微核法是估算事故受照者所受剂量的一种较为理想的方法。     

山东济宁辐射事故受照人员生物剂量估算及彗星电泳检测分析

目的探索特大剂量照射后外周血和骨髓染色体培养方法，拟合6Gy以上大剂量照射染色体双着丝点＋环剂量-效应曲线，对山东济宁“10．21”事故受照者进行准确生物剂量估算和DNA损伤检测。方法采集2例受照者外周血和骨髓细胞，制备染色体标本，计数双（多）着丝点＋环数目；用正常离体人血拟合6～22Gy双＋环剂量效应曲线及数学方程；对2例事故受照者进行生物剂量估算。用碱性单细胞凝胶电泳方法检测受照者外周血DNA损伤。结果B的外周血染色体双＋环平均数为4．47个／细胞；A的外周血培养无分裂细胞，骨髓染色体双＋环平均数为9．15个／细胞。用6—22Gy剂量效应方程估算全身平均受照剂量，B为9．4Gy，A为19．5Gy。单细胞凝胶电泳可见2例受照者的多数彗星细胞呈小头大尾形状。结论用新建立的6～22Gy染色体畸变剂量效应曲线估算2例受照者的生物剂量，已分别达到极重度骨髓型放射病和肠型放射病水平。     

Chromosomal Aberration in Peripheral Lymphocytes and Doses to the Active Bone Marrow in Radiotherapy of Prostate Cancer

BACKGROUND AND PURPOSE: Radiotherapy plays an important role in the management of prostate cancer. Epidemiological data indicate a small but significant risk of radiation-induced leukemia after radiotherapy which might be related to the high mean bone marrow dose associated with radiotherapy of prostate cancer. The purpose of the study was to investigate the relation between the mean bone marrow dose and unstable chromosome aberrations in peripheral blood lymphocytes in patients undergoing conformal radiotherapy for prostate cancer as a possible indicator of risk. Endometrial cancer patients were also included for comparison. PATIENTS AND METHODS: Nine patients, six with prostate cancer (60-73 years old) and three with endometrial cancer (61-81 years old) treated with radiotherapy were included in the study. The non-bony spaces inside the pelvic bones were outlined on every CT slice using the treatment planning system and mean doses to the bone marrow calculated. Blood samples of the patients were obtained at different times before, during and at the end of treatment. Lymphocytes were cultured in the usual way and metaphases scored for dicentric aberrations. RESULTS: 46 samples from nine patients were obtained. The mean number of metaphases analyzed per sample was 180 with a range from 52 to 435. The mean bone marrow doses for prostate cancer patients ranged from 2.8 to 4.2 Gy and for endometrial cancer patients from 12.8 to 14.8 Gy. The aberration yield increased with the planning target volume and the mean bone marrow dose. CONCLUSION: The yield of dicentric aberrations for prostate cancer patients correlated closely with the mean bone marrow dose albeit the induction of dicentrics occurred in mature T lymphocytes most of which were probably in transit through the irradiated volumes. Therefore, the observed relationship between dicentrics and mean bone marrow doses are indirect.     

Chromosome aberrations in peripheral lymphocytes of patients irradiated with 15-MeV-photons for Morbus Hodgkin

Chromosome aberrations in peripheral lymphocytes of two Morbus Hodgkin patients were analyzed before and during the ongoing radiotherapy. Venous blood was taken 5 min after and before a successive irradiation in order to examine the dose dependence as well as the influence of mixed unirradiated and irradiated lymphocytes on the aberration rate. Both patients showed an overdispersed distribution of dicentric chromosomes and acentric fragment from the outset of therapy and independent of the time blood was taken. The dose-effect relationship established for both types of aberrations by the Maximum-Likelihood approach may best be described as being linear. The dose effect curves 5 min after a fraction did not differ from those calculated for a time thereafter. However, after the first two irradiations, the rate of dicentric chromosomes in the blood samples taken at a later time was about twice as high as that in the samples taken 5 min after irradiation. Dicentric chromosomes were twice more frequent during the entire radiotherapy than acentric fragments and about 30 times more frequent than centric ring chromosomes.     

Chromosome aberrations in patients irradiated for pelvic tumours

Peripheral blood lymphocytes of patients undergoing radiation therapy for pelvic tumours have been examined for the presence of dicentric and centric ring chromosomes. Blood samples were taken, by venipuncture, prior to the first radiotherapy session and 24 h after radiotherapy sessions to allow the mixing of the irradiated lymphocytes in the circulating blood. The yield of dicentrics and centric rings was best fitted by a straight line which, according the maximum likelihood method, corresponds to Y = 1.77 +/- 0.0003 10(-2) D. On this basis the dose inducing ten dicentrics or rings is 5.62 Gy at the target volume and, thus, is intermediate between the doses at the target volumes displaying the same effects in patients treated for mammary carcinoma (15 Gy) or for ankylosing spondylitis (2 Gy).     

Effects of local single and fractionated X-ray doses on rat bone marrow blood flow and red blood cell volume

Time and dose dependent changes in blood flow and red blood cell volume were studied in the locally irradiated bone marrow of the rat femur after single and fractionated doses of X-rays. With the single dose of 10 Gy the bone marrow blood flow although initially reduced returned to the control levels by seven months after irradiation. With doses greater than or equal to 15 Gy the blood flow was still significantly reduced at seven months. The total dose levels predicted by the nominal standard dose equation for treatments in three, six or nine fractions produced approximately the same degree of reduction in the bone marrow blood flow seven months after the irradiation. However, the fall in the red blood cell volume was from 23 to 37% greater in the three fractions groups compared with that in the nine fractions groups. Using the red blood cell volume as a parameter the nominal standard dose formula underestimated the severity of radiation damage in rat bone marrow at seven months for irradiation with small numbers of large dose fractions.     

Chromosome aberrations in patients treated with telecobalt therapy for glioblastoma

The yield of dicentric chromosomes has been recorded in peripheral blood lymphocytes of patients undergoing telecobalt therapy for glioblastoma. Blood samples were taken by venipuncture, prior to the first radiotherapy session and 24 h after 10, 20 and 30 Gy to the tumor volume. On the basis of the maximum likelihood method, the yield of chromosome aberrations was best fitted by a linear quadratic dose-response relationship. According to this relationship, the dose inducing ten dicentrics at the target volume is 58 Gy, a value considerably higher than those found after radiotherapy for mammary carcinoma (15 Gy) or for pelvic tumors (5.62 Gy). Our results indicate that, in the case of fractionated exposures, confined to a small volume of the body, it is not possible to estimate the total dose administered and that the method only provides an estimate of the proportion of the lymphocytes irradiated.     

Intercomparison of translocation and dicentric frequencies between laboratories in a follow-up of the radiological accident in Estonia

PURPOSE: To perform an interlaboratory comparison of FISH chromosome painting and to study the time-course of translocations and dicentrics in three accident victims exposed to radiation. Also, to use the data in the validation of the FISH technique as a retrospective dosimeter. MATERIALS AND METHODS: Twelve blood samples were collected during 4 years from three subjects exposed to radiation in an accident in Estonia in 1994 involving gamma-radiation from a 137Cs source. Two of the subjects were exposed during approximately 7 h, both receiving a protracted dose of about 1 Gy and also localized exposure. The third subject received a protracted whole-body dose of 2.7 Gy during 4 weeks as well as a short-term partial-body dose. Preparations from 48-h metaphase cultures were painted by the FISH technique using routine methods and probe cocktails in four laboratories. Samples from each subject were analysed in two different laboratories that used different combinations of whole chromosome probes. The PAINT nomenclature was applied when recording chromosome aberrations. RESULTS: The intercomparison of FISH analysis data showed reasonable similarities between laboratories, the largest discrepancy being 21% in the frequency of two-way translocations in subject 3. Half-time calculations, based on combined data sets from two laboratories, showed that dicentrics decreased rapidly with half-times of approximately 2 years. In all cases, the initial dicentric yields were lower than the initial translocation yields. During the 4-year follow-up, the frequencies of all translocations in cells containing only simple rearrangements fell on average to about 65% of their initial value. Two-way translocations were slightly more persistent than all translocations. The average half-time was about 8 years for two-way translocations and around 6 years for all translocations. Cells containing complex rearrangements were few in number and they disappeared with time. In general, the inclusion of complex cells caused a more rapid fall in aberration yield. CONCLUSIONS: In general, the results imply that relatively consistent scoring data were obtained with different chromosome painting protocols. They also support the idea that the reduction of translocations with time is associated with partial-body irradiation.