Time filter

Source Type

Buenos Aires, Argentina

Di Giorgio M.,Autoridad Regulatoria Nuclear ARN | Barquinero J.F.,Autonomous University of Barcelona | Vallerga M.B.,Autoridad Regulatoria Nuclear ARN | Radl A.,Autoridad Regulatoria Nuclear ARN | And 17 more authors.
Radiation Research | Year: 2011

Well-defined protocols and quality management standards are indispensable for biological dosimetry laboratories. Participation in periodic proficiency testing by interlaboratory comparisons is also required. This harmonization is essential if a cooperative network is used to respond to a mass casualty event. Here we present an international intercomparison based on dicentric chromosome analysis for dose assessment performed in the framework of the IAEA Regional Latin American RLA/9/054 Project. The exercise involved 14 laboratories, 8 from Latin America and 6 from Europe. The performance of each laboratory and the reproducibility of the exercise were evaluated using robust methods described in ISO standards. The study was based on the analysis of slides from samples irradiated with 0.75 (DI) and 2.5 Gy (DII). Laboratories were required to score the frequency of dicentrics and convert them to estimated doses, using their own doseâ€"effect curves, after the analysis of 50 or 100 cells (triage mode) and after conventional scoring of 500 cells or 100 dicentrics. In the conntional scoring, at both doses, all reported frequencies were considered as satisfactory, and two reported doses were considered as questionable. The analysis of the data dispersion among the dicentric frequencies and among doses indicated a better reproducibility for estimated doses (15.6% for DI and 8.8% for DII) than for frequencies (24.4% for DI and 11.4% for DII), expressed by the coefficient of variation. In the two triage modes, although robust analysis classified some reported frequencies or doses as unsatisfactory or questionable, all estimated doses were in agreement with the accepted error of ±±0.5 Gy. However, at the DI dose and for 50 scored cells, 5 out of the 14 reported confidence intervals that included zero dose and could be interpreted as false negatives. This improved with 100 cells, where only one confidence interval included zero dose. At the DII dose, all estimations fell within ±±0.5 Gy of the reference dose interval. The results obtained in this triage exercise indicated that it is better to report doses than frequencies. Overall, in both triage and conventional scoring modes, the laboratory performances were satisfactory for mutual cooperation purposes. These data reinforce the view that collaborative networking in the case of a mass casualty event can be successful. © 2011 by Radiation Research Society.

Sugarman S.L.,Oak Ridge Assoc Universities | Livingston G.K.,Oak Ridge Assoc Universities | Stricklin D.L.,Applied Research Assoc | Abbott M.G.,Oak Ridge Assoc Universities | And 12 more authors.
Health Physics | Year: 2014

Response to a large-scale radiological incident could require timely medical interventions to minimize radiation casualties. Proper medical care requires knowing the victim's radiation dose. When physical dosimetry is absent, radiation-specific chromosome aberration analysis can serve to estimate the absorbed dose in order to assist physicians in the medical management of radiation injuries. A mock exercise scenario was presented to six participating biodosimetry laboratories as one individual acutely exposed to Co under conditions suggesting whole-body exposure. The individual was not wearing a dosimeter and within 2-3 h of the incident began vomiting. The individual also had other medical symptoms indicating likelihood of a significant dose. Physicians managing the patient requested a dose estimate in order to develop a treatment plan. Participating laboratories in North and South America, Europe, and Asia were asked to evaluate more than 800 electronic images of metaphase cells from the patient to determine the dicentric yield and calculate a dose estimate with 95% confidence limits. All participants were blind to the physical dose until after submitting their estimates based on the dicentric chromosome assay (DCA). The exercise was successful since the mean biological dose estimate was 1.89 Gy whereas the actual physical dose was 2 Gy. This is well within the requirements for guidance of medical management. The exercise demonstrated that the most labor-intensive step in the entire process (visual evaluation of images) can be accelerated by taking advantage of world-wide expertise available on the Internet. © 2014 Health Physics Society.

Molina P.,CONICET | Ortega F.,CONICET | Marcazzo J.,CONICET | Santiago M.,CONICET | And 3 more authors.
Radiation Measurements | Year: 2015

The kinetic parameters of dosimetric peaks of CaF2:Tm (TLD-300) were found by employing a kinetics model derived from differential equations describing the carriers traffic but without resorting to the quasi-equilibrium approximation. Since both shape and position of glow peaks were observed not to change with dose, retrapping rates have been assumed negligible compared to rates of thermal release of electrons. The reported results show that the quasi-equilibrium approximation does not hold, an approximation used for derivation of first order kinetics, which is the kinetics employed so far for analyzing glow curves of the TLD-300. © 2015 Published by Elsevier Ltd.

Santiago M.,National University of Central Buenos Aires | Santiago M.,CONICET | Marcazzo J.,National University of Central Buenos Aires | Marcazzo J.,CONICET | And 4 more authors.
Radiation Measurements | Year: 2011

Borates have shown to be efficient materials to be employed for ionizing radiation detection given their tissue-equivalent characteristics. Usually, the efficiency of these compounds is largely dependent on the preparation methods and conditions. In this work nominally pure and Dy-doped strontium borates have been prepared by sol-gel method. The thermoluminescence and radioluminescence of the resulting borates have been investigated and correlated to their structural characteristics. © 2011 Elsevier Ltd. All rights reserved.

Molina P.,National University of Central Buenos Aires | Molina P.,CONICET | Santiago M.,National University of Central Buenos Aires | Santiago M.,CONICET | And 5 more authors.
Radiation Measurements | Year: 2011

The radioluminescence (RL) properties of K 2YF 5 crystals doped with Ce 3+, Tb 3+ and Dy 3+ under ionizing irradiation excitation have been studied for the first time. The main objective of this work has been to assess the feasibility of using these crystals as detectors for fiberoptic radioluminescent dosimetry. In particular, it has been found that the RL intensity from both K 2YF 5:Tb (10%) and K 2TbF 5 is comparable to that from a commercial Al 2O 3:C crystal. Longer wavelength emission from these fluorides makes simple optical filtering technique possible to use in order to avoid the stem effect. Afterglow decay times for these fluorides have been found to be similar to that for Al 2O 3:C and, in particular, K 2TbF 5 does not show longer afterglow decay time compared to Al 2O 3:C. © 2011 Elsevier Ltd. All rights reserved.

Discover hidden collaborations