[en] The International Atomic Energy Agency (IAEA) published the Standard Syllabus for Post Graduate Educational Courses in Radiation Protection and the Safety of Radiation Sources in 2002. Along more than two decades, Argentina has obtained valuable experience on building professional knowledge at postgraduate level in Radiation Protection and Nuclear Safety. Such experience made advisable to review the IAEA Standard Syllabus and to modify it accordingly. The whole content of the Standard Syllabus is included in the syllabus developed for the Argentinean Regional Post Graduate Course in Radiation Protection and Safety of Radiation Sources. But a few additional topics were incorporated and changes were introduced in the sequence of subjects. The paper describes those modifications and explains the pedagogic motivations that induce them. (Author) 3 refs

[en] Several endpoints have been used for monitoring human populations for environmental or occupational exposure to genotoxic agents, particularly ionizing radiation. The cytokinesis-block micronucleus (MN) assay in peripheral lymphocytes is a reliable method for assessing radiation induced chromosomal damage (DNA breaks and mitotic spindle disturbances) and thus, a suitable dosimeter for estimating in vivo whole body exposures. To further define the use of this assay in biological dosimetry, a study to determine the influence of age, sex and life style factors (smoking habit) on the spontaneous and radiation induced MN frequencies was performed. The estimation of MN frequencies was analyzed in lymphocytes cultures from 50 healthy donors aged between 4 and 62 years. On the basis of their smoking habit they were divided into 2 groups. A fraction of the sample was irradiated in vitro with Y rays in the range of 0.35 Gy to 4 Gy. A statistically significant influence on the spontaneous MN frequency was observed (R² = 0.59) when the variables age and smoking habit were analyzed and also a statistically significant influence on the radiation induced MN frequency was obtained (R² = 0.96) when dose, age and smoking habit were studied. Sex did not influence MN variability significantly but there was a greater dispersion in the results for females when compared to males, possibly due to the loss of X chromosomes. The comparison of the data from smoking to non smoking donors supports the convenience to take into account the smoking habit for estimating in vivo whole body exposures to γ-rays for doses below 2 Gy. (author)

[en] Several endpoints have been used for monitoring human populations for environmental or occupational exposure to genotoxic agents, particularly ionizing radiation. The cytokinesis-block micronucleus (MN) assay in peripheral lymphocytes is a reliable method for assessing radiation induced chromosomal damage (DNA breaks and mitotic spindle disturbances) and thus, a suitable dosimeter for estimating in vivo whole body exposures. To further define the use of this assay in Biological Dosimetry, a study to determine the influence of age, sex and life style factors (smoking habit) on the spontaneous and radiation induced MN frequencies was performed. The estimation of MN frequencies was analyzed in lymphocytes cultures from 50 healthy donors aged between 4 and 62 years. On the basis of their smoking habit they were divided into 2 groups. A fraction of the sample was irradiated in vitro with γ rays in the range of 0.35 Gy to 4 Gy. A statistically significant influence on the spontaneous MN frequency was observed (R² = 0.59) when the variables age and smoking habit were analyzed and also a statistically significant influence on the radiation induced MN frequency was obtained (R² = 0.86) when dose, age and smoking habit were studied. Sex did not influence MN variability significantly but there was a greater dispersion in the results for females when compared to males, possibly due to the loss of X chromosomes. The comparison of the data from smoking donors to non smoking donors supports the convenience of taking into account the smoking habit for estimating in vivo whole body exposure to γ rays for doses below 2 Gy. (author). 8 refs., 3 figs., 1 tab

[en] The micronucleus assay has a great disadvantage to reduced sensibility for the detection induced damage for the drops dose radiation low lineal transference gives energy, due to its spontaneous high frequency that shows timbers a wide variability interindividual. It is suggested that diverse denominated factors give confusion, such as the I inhabit gives to smoke, the age and the sex contribute to the observed variability. Data give our laboratory they indicate a significantly positive correlation the spontaneous radioinduced frequency micronucleus with the age and the one inhabits to smoke, being the I inhabit to smoke the factor confusion bigger influence. These summations seemed to justify the study the relationships dose answer separately for smoking donors and smoking no, using gamma radiation gives cobalt 60

[en] Several endpoints have been used for monitoring human population that have been exposed at work or in the environment to genotoxic agents, particularly to ionizing radiation. The cytokinesis-block micronucleus (MN) assay in peripheral lymphocytes is a reliable method for evaluating radiation induced chromosomal damage (DNA breaks and mitotic spindle disturbances) and thus, a suitable dosimeter for estimating in vivo whole body exposures. A research to determine the influence of age, sex and life style factors (smoking habits) on the MN spontaneous and radiation induced frequencies was carried out in order to define the use of this assay in Biological Dosimetry. The estimation of MN frequencies was analyzed in lymphocytes cultures from 50 health donors aged between 4 and 60 years. Based on the smoking habits, they were divided into 2 groups. A fraction of the sample was irradiated in vitro with γ-rays in the range of 0.35 Gy to 4 Gy. A statistically significant influence on the spontaneous MN frequency was observed (R² = 0.59) when the variables age and smoking habit were analyzed, and a statistically significant influence on the radiation induced MN frequency was also obtained (R² = 0.86) when dose, age and smoking habit were studied. Sex did not influence significantly MN variability, but there was a greater dispersion in the results obtained from female donors, when compared to males, possibly due to the loss of X chromosomes. The comparison of the data from smoking donors to the data from non smoking donors supports the convenience of taking into account the smoking habit for estimating in vivo whole body exposure to γ-rays for doses below 2 Gy. (authors). 8 refs., 3 figs., 2 tabs

[en] Radiation induced unstable chromosome aberration frequency (dicentrics and centric rings) in peripheral lymphocytes is a powerful tool for early biological dose assessment in cases of accidental overexposures. Occupational accidents or overexposures of people to ionizing radiation usually involve low LET sources (X-rays or γ-rays). A criticality accident, less frequent but more complex in its evaluation, involves a radiation emission of a mixed neutron and γ-ray field. From the observed frequency of unstable chromosome aberrations it is not possible to discriminate between those aberrations due to γ-rays and those due to neutrons. However, if the γ-ray/neutron ratio is known from physical dosimetry measurements it is possible to estimate both components of the total dose applying an iterative method and assuming that both radiation qualities are additive in inducing chromosome aberrations and the aberrations do not show overdispersion compared to Poisson distribution. In order to evaluate the efficiency of inducing unstable chromosome aberration of a neutron- γ ray field and the estimation of both components of the total dose using unstable chromosome aberration frequency as end point, we have performed three in vitro blood sample irradiations in a suitable RA1 research reactor facility, near to the core, using a specially designed device. Physical γ dose assessments were performed using thermoluminescent dosimeters (TLD 700). Neutron doses were calculated using the spectra obtained by WIMS and ANISN codes. Spectrometric calculi in the fast energy zone (the one with higher Kerma factor) were validated with fluency measurements by activation using In detectors (In¹¹⁵(n,n)In^115m). Doses corresponding to thermal, intermediate and fast energy zones were calculated using blood equivalent tissue Kerma factors from ICRU 44. The measurements indicates that fast neutrons contribute mainly to the total neutron dose. Biological dose estimation of the γ and neutron component was performed using the Co⁶⁰ γ-ray (our laboratory) and fission neutrons (Lloyd, 1986) in vitro dose response curves and applying the iterative process described in the IAEA Report (1986). Physical and biological dose estimations do not differ significantly, indicating that it is appropriate the use of a fission neutron dose response curve for the biological dose assessment in this overexposure scenario. (author)

[en] Ionizing radiation induces DNA double-strand breaks (DSBs) and their interaction and illegitimate recombination produces chromosomal aberrations. Stable chromosomal aberrations comprise inter-chromosomal events (translocations) and intra-chromosomal events (inversions). When DSBs induction and interaction is done at random, and the proximity effects are neglected, the expected relation between translocations and inversions is F=86, based on chromosome arm length. The number of translocations and inversions is analyzed by using G-banding in 16 lymphocytes cultures from blood samples acutely irradiated with γ-rays (dose range: 0,5 Gy - 3 Gy). The result obtained was: F=13,5, significantly smaller than F=86. Literature data show similar small F values, but strongly spread. The excess of inversions could be explained by a 'proximity effect', it means that more proximate DSBs have more interaction probability. Therefore, it is possible to postulate a special chromosome arrangement during irradiation and the subsequent interval. We propose a model where individual chromosomes show spherical confinement with some degree of overlapping and DSBs induction proportional to cross section. A DSBs interaction probability function with cut-off length= 1μ is assumed. According to our results, the confinement volume is ≅ 6.4% of the nuclear volume. Nevertheless, we presume that large spread in F data could be due to temporal variation in overlapping and spatial chromosomal confinement. (authors). 14 refs

[en] Ionizing radiation induces DNA double strand breaks (DSBs) and their interaction and illegitimate recombination produces chromosome aberrations. Stable chromosome aberrations comprise inter-chromosomal events (translocations) and intra-chromosomal events (inversions). Assuming DSBs induction and interaction is completely random and neglecting proximity effects, the expected ratio of translocations to inversions is F=86, based on chromosome arm lengths. We analyzed the number of translocations and inversions using G-banding, in 16 lymphocyte cultures from blood samples acutely irradiated with γ-rays (dose range: 0.5 Gy - 3 Gy). Our results give F=13.5, significantly smaller than F=86. Literature data show similar small F values but strongly spread. The excess of inversions could be explained by a 'proximity effect', it means that more proximate DSBs have an extra probability of interaction. Therefore, it is possible to postulate a special chromosome arrangement during irradiation and the subsequent interval. We propose a model where individual chromosomes show spherical confinement with some degree of overlapping and DSBs induction proportional to cross section. We assume a DSBs interaction probability function with cut-off length = 1 μm. According to our results the confinement volume is = 6.4% of the nuclear volume. Nevertheless, we propose that large spread in F data could be due to temporal variation in overlapping and spatial chromosome confinement. (author)

[en] Ionizing radiation induces DNA double strand breaks (DSBs) and their interaction and illegitimate recombination produces chromosome aberrations. Stable chromosome aberrations comprise inter-chromosomal events (translocations) and intra-chromosomal events (inversions). Assuming DSBs induction and interaction is completely random and neglecting proximity effects, the expected ratio of translocations to inversions is F=86, based on chromosome arm lengths. We analyzed the number of translocations and inversions using G-banding, in 16 lymphocyte cultures from blood samples acutely irradiated with γ-rays (dose range: 0.5Gy-3Gy). Our results give F=13.5, significantly smaller than F=86. Literature data show similar small F values but strongly spread. The excess of inversions could be explained by a 'proximity effect', it means that more proximate DSBs have an extra probability of interaction. Therefore, it is possible to postulate a special chromosome arrangement during irradiation and the subsequent interval. We propose a model where individual chromosomes show spherical confinement with some degree of overlapping and DSBs induction proportional to cross section. We assume a DSBs interaction probability function with cut-off length = 1 μ. We propose that large spread in F data could be due to temporal variation in overlapping and spatial chromosome confinement. (author). 14 refs

[en] Short communication