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PubMed2006

A transferability study of the EPR-tooth-dosimetry technique.

The transferability of a measurement protocol from one laboratory to another is an important feature of any mature, standardised protocol. The electron paramagnetic resonance (EPR)-tooth dosimetry technique that was developed in Scientific Center for Radiation Medicine, AMS, Ukraine (SCRM) for routine dosimetry of Chernobyl liquidators has demonstrated consistent results in several inter-laboratory measurement comparisons. Transferability to the EPR dosimetry laboratory at the National Institute of Standards and Technology (NIST) was examined. Several approaches were used to test the technique, including dose reconstruction of SCRM-NIST inter-comparison samples. The study has demonstrated full transferability of the technique and the possibility to reproduce results in a different laboratory environment.

Electron Spin Resonance Spectroscopy↗

PubMed2006

Scanning an individual monitoring database for multiple occurrences using bi-gram analysis.

Maintaining the integrity of the databases is one of the important aspects of quality assurance at individual monitoring services and national dose registers. This paper presents a method for finding and preventing the occurrence of duplicate entries in the databases that can occur, e.g. because of a variable spelling or misspelling of the name. The method is based on bi-gram text analysis techniques. The methods can also be used for retrieving dose data in historical databases in the framework of dose reconstruction efforts of persons of whom the spelling of the name as originally entered, possibly decades ago, is uncertain.

Algorithms↗

PubMed2007

Radiation exposure to the population of Europe following the Chernobyl accident.

On the occasion of the 20th anniversary of the Chernobyl accident an attempt has been made to evaluate the impact of the Chernobyl accident on the global burden of human cancer in Europe. This required the estimation of radiation doses in each of the 40 European countries. Dose estimation was based on the analysis and compilation of data either published in the scientific literature or provided by local experts. Considerable variability has been observed in exposure levels among the European populations. The average individual doses to the thyroid from the intake of (131)I for children aged 1 y were found to vary from approximately 0.01 mGy in Portugal up to 750 mGy in Gomel Oblast (Belarus). Thyroid doses to adults were consistently lower than the doses received by young children. The average individual effective doses from external exposure and ingestion of long-lived radiocaesium accrued in the period 1986-2005 varied from approximately 0 in Portugal to approximately 10 mSv in Gomel Oblast (Belarus) and Bryansk Oblast (Russia). The uncertainties in the dose estimates were subjectively estimated on the basis of the availability and reliability of the radiation data that were used for dose reconstruction in each country.

Adult↗

PubMed1997

Monitoring distant fallout: the role of the Atomic Energy Commission Health and Safety Laboratory during the Pacific tests, with special attention to the events following BRAVO.

The fallout from test BRAVO in March 1954 has had scientific, political, and social implications that have continued for more than 40 years. The test resulted in serious injury to the people of the Marshall Islands and 23 men on a nearby Japanese fishing boat. Prior to BRAVO there was insufficient appreciation of the dangers of fallout to people living downwind from surface or near-surface explosions of megaton weapons. In the absence of sufficient preplanning for fallout monitoring beyond the test-sites of earlier smaller yield tests, and as a result of the concern of the photographic film manufacturers, the Atomic Energy Commission Health and Safety Laboratory, now the Department of Energy Environmental Measurements Laboratory, was requested to develop a program of fallout surveillance. Beginning with Operation IVY in 1952, these surveys included aerial monitoring of the islands of the mid and western Pacific, as well as establishment of fallout monitoring stations in the United States and abroad. The first evidence of the post-BRAVO fallout was detected by a Atomic Energy Commission Health and Safety Laboratory instrument installed on the atoll of Rongerik, where 28 military personnel were stationed. The results of radiation surveys conducted immediately after BRAVO, as well as the reports of medical investigations, radioecological studies, and dose reconstruction that have been conducted by many laboratories over the years have been available from the beginning in unclassified form. However, from the time of the fallout, and continuing to the present, there have been many unanswered questions about what happened during the hours immediately after the fallout was reported. No formal investigation of the circumstances of the fallout was ever conducted, and there were serious misrepresentations of the facts in the official statements made at the time.

Humans↗

PubMed2000

The U.S.-Russian radiation health effects research program in the Southern Urals.

The Joint Coordinating Committee for Radiation Effects Research (JCCRER) was established through a bilateral U.S.-Russian agreement to support research and exchange information on radiation health effects. The U.S. member agencies include the Department of Energy (DOE), Nuclear Regulatory Commission (NRC), Department of Health and Human Services (DHHS), Department of Defense (DoD), National Aeronautics and Space Administration (NASA), and Environmental Protection Agency (EPA). The Russians are represented by the Ministries of Emergencies (EMERCOM), Atomic Energy (MINATOM) and Health (MINZDRAV), and the Russian Academy of Sciences (IBRAE). The focus of this research is on the workers from the Mayak Production Association (MAYAK) in the Southern Urals and on the neighboring populations along the Techa River exposed to contamination from the plant. The goal of the program is to better define the relationship between the health effects and the chronic low dose and dose-rate exposure, these data being essential to validate current radiation protection standards and practices. The current primary areas of JCCRER research include dose reconstruction, epidemiologic health studies, molecular epidemiology/biodosimetry, and the creation of tissue banks. The organization of the ongoing research conducted under the aegis of the JCCRER and the rationale for this work are described.

Environment↗

PubMed2002

A re-evaluation of the 131I atmospheric releases from the Hanford site.

The atmospheric release of 131I from the Hanford site for the 1950's and 1960's, focused on the period of releases after the year 1950, has been re-evaluated using processing plant stack monitoring data to address a series of questions and concerns that have arisen related to the source term. Historical stack monitoring data have been used to re-assess the releases by creating either a release factor to use with the calculated plant throughput or using the stack monitoring results as the basic estimate, and the results have been verified using historical atmospheric monitoring data from a location several kilometers distant. Uncertainties in all of the historical data have been addressed in the re-assessment. Compared to the original estimate between 1950 and 1971 of 2.46 +/- 0.71 PBq, the stack monitoring results show a release of 131I to the atmosphere of 1.55 +/- 0.23 PBq. The concurrent atmospheric monitoring results imply a release of 1.75 +/- 0.11 PBq over the same period, but this result is inflated by inclusion of global fallout The total effective dose estimated to a full-time, nearby adult resident from 131I using the Heeb source term from 1950 through 1972 is 0.73 mSv; using the source term based on stack monitoring data in the Hanford Environmental Dose Reconstruction project models, it is 0.51 mSv.

Air Pollutants, Radioactive↗

PubMed2004

The application of retrospective luminescence dosimetry in areas affected by fallout from the semipalatinsk nuclear test site: an evaluation of potential.

Luminescence retrospective dosimetry techniques have been applied with ceramic bricks to determine the cumulative external gamma dose due to fallout, primarily from the 1949 test, in populated regions lying NE of the Semipalatinsk Nuclear Test Site in Altai, Russia, and the Semipalatinsk region, Kazakhstan. As part of a pilot study, nine settlements were examined, three within the regions of highest predicted dose (Dolon in Kazakshstan; Laptev Log and Leshoz Topolinskiy in Russia) and the remainder of lower predicted dose (Akkol, Bolshaya Vladimrovka, Kanonerka, and Izvestka in Kazakshstan; Rubtsovsk and Kuria in Russia) within the lateral regions of the fallout trace due to the 1949 test. The settlement of Kainar, mainly affected by the 24 September 1951 nuclear test, was also examined. The bricks from this region were found to be generally suitable for use with the luminescence method. Estimates of cumulative absorbed dose in air due to fallout for Dolon and Kanonerka in Kazakshstan and Leshoz Topolinskiy were 475 +/- 110 mGy, 240 +/- 60 mGy, and 230 +/- 70 mGy, respectively. The result obtained in Dolon village is in agreement with published calculated estimates of dose normalized to Cs concentration in soil. At all the other locations (except Kainar) the experimental values of cumulative absorbed dose obtained indicated no significant dose due to fallout that could be detected within a margin of about 25 mGy. The results demonstrate the potential suitability of the luminescence method to map variations in cumulative dose within the relatively narrow corridor of fallout distribution from the 1949 test. Such work is needed to provide the basis for accurate dose reconstruction in settlements since the predominance of short-lived radionuclides in the fallout and a high degree of heterogeneity in the distribution of fallout are problematic for the application of conventional dosimetry techniques.

Luminescent Measurements↗

PubMed2006

Revisions to the ORNL series of adult and pediatric computational phantoms for use with the MIRD schema.

The age-dependent series of stylized computational phantoms developed at the Oak Ridge National Laboratory in the late 1970's to early 1980's has found wide applicability in dosimetry studies ranging from dose coefficient compilations for external and internal photon emitters, simulations of patient radiological exams, and dose reconstruction activities. In the present study, we report on a series of revisions to the Oak Ridge National Laboratory series for their intended use within the MIRD schema of medical internal dosimetry. These revisions were made to (1) incorporate recent developments in stylized models of the head, brain, kidneys, rectosigmoid colon, and extra-pulmonary airways; (2) incorporate new models of the salivary glands and the mucosa layer of the urinary bladder, alimentary tract organs, and respiratory airways; (3) adopt reference values of elemental tissue compositions and mass densities from ICRP Publication 89 and ICRU Report 46; (4) provide for explicit treatment of left and right organs within organ pairs; (5) provide for a systematic tabulation of electron absorbed fractions as a function of energy and subject age for all internal organs; and (6) provide for methods of deriving patient-specific values of the specific absorbed fraction for both electrons and photons through interpolation/extrapolation of their phantom-derived values. While tomographic computational phantoms provide improved anatomic realism given the CT or MR image sets used in their construction, there does not yet exist a comprehensive series of reference pediatric tomographic phantoms, nor the ability to simulate very fine anatomic structures as can be modeled via mathematical approximation. Consequently, stylized pediatric phantoms will continue to fill this data need in medical dosimetry.

Adult↗

PubMed2006

Environmental surveillance at Los Alamos: an independent reassessment of historical data.

Since 1971, a series of annual Environmental Surveillance ... reports have served as the official public record of Los Alamos National Laboratory's (LANL) environmental performance. In northern New Mexico, where past LANL emissions are a public health concern, there is public skepticism over the accuracy of information contained in these reports. To test the hypothesis that LANL Environmental Surveillance ... reports systematically understate past emissions, we compared the data on releases in LANL's own internal Occurrence Reports Collection (ORC) to the data reported to the public in the Environmental Surveillance ... reports. A data set of 89 environmental occurrences recorded in the ORC in the time period from 1971 through 1980 was assembled. We did not find a systematic pattern of quantitative underreporting of source terms. However, 17 of the 89 (19%) environmental occurrences recorded in the ORC were not reported to the public in the Environmental Surveillance ... reports. The observed discrepancies are discussed in terms of their relevance to public health concerns. Methodological caveats dictate restraint in applying these findings beyond the scope of the relative comparison performed here. Possible social origins for the rejected hypothesis are discussed. Areas for further consideration by the Centers for Disease Control's dose reconstruction study of LANL are identified.

Environmental Monitoring↗

PubMed1997

Acute radiation dermatitis following radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia.

Radiation exposure during fluoroscopic imaging poses potential risks to patients and physicians, especially during protracted cardiovascular or radiological interventional procedures. We describe a woman with refractory paroxysmal supraventricular tachycardia who underwent radiofrequency catheter ablation of the slow pathway involved in atrioventricular nodal reentrant tachycardia. The patient subsequently returned 4 weeks later with acute radiation dermatitis that was retrospectively attributed to a malfunction in the fluoroscopy unit that lacked a maximum current output cut-off switch. Using dose reconstruction studies and her estimated biological response, we determined that she received between 15 and 20 Gy (1 Gy = 100 rads) to the skin on her back during the procedure. The exposure will result in an increase in her lifelong risk of skin and lung cancer. This article underscores the potential for radiation-induced injury during lengthy therapeutic procedures using x-ray equipment.

Acute Disease↗

PubMed2005

Experimental verification of a portal dose prediction model.

Electronic portal imaging devices (EPIDs) can be used to measure a two-dimensional (2D) dose distribution behind a patient, thus allowing dosimetric treatment verification. For this purpose we experimentally assessed the accuracy of a 2D portal dose prediction model based on pencil beam scatter kernels. A straightforward derivation of these pencil beam scatter kernels for portal dose prediction models is presented based on phantom measurements. The model is able to predict the 2D portal dose image (PDI) behind a patient, based on a PDI without the patient in the beam in combination with the radiological thickness of the patient, which requires in addition a PDI with the patient in the beam. To assess the accuracy of portal dose and radiological thickness values obtained with our model, various types of homogeneous as well as inhomogeneous phantoms were irradiated with a 6 MV photon beam. With our model we are able to predict a PDI with an accuracy better than 2% (mean difference) if the radiological thickness of the object in the beam is symmetrically situated around the isocenter. For other situations deviations up to 3% are observed for a homogeneous phantom with a radiological thickness of 17 cm and a 9 cm shift of the midplane-to-detector distance. The model can extract the radiological thickness within 7 mm (maximum difference) of the actual radiological thickness if the object is symmetrically distributed around the isocenter plane. This difference in radiological thickness is related to a primary portal dose difference of 3%. It can be concluded that our model can be used as an easy and accurate tool for the 2D verification of patient treatments by comparing predicted and measured PDIs. The model is also able to extract the primary portal dose with a high accuracy, which can be used as the input for a 3D dose reconstruction method based on back-projection.

Algorithms↗

PubMedDate not supplied

The Agency for Toxic Substances and Disease Registry's role in development and application of biomarkers in public health practice.

An overview of the Agency for Toxic Substances and Disease Registry's (ATSDR) biomarker program is presented in the context of the paradigm for biomarkers developed by the National Research Council (NRC, 1987, 1991). The status and projected utility of four biomarker studies conducted by NRC and sponsored by ATSDR, the Environmental Protection Agency (EPA), and the National Institute of Environmental Health Sciences (NIEHS) are discussed. These studies include a review of relevant research on biomarkers for specific toxicologic end points, including reproductive toxicology, pulmonary toxicology, neurotoxicology, and immunotoxicology. Also, the scope of related research on exposure characterization being conducted by the ATSDR-sponsored research program at Rutgers University is reviewed. The potential impact of biomarkers on public health assessments and on the range of ATSDR programs is described. Specifically, the role of biomarkers in dose reconstruction, in ATSDR's health studies program, and in the emerging field of molecular epidemiology is reviewed. In addition, future directions and research needs are addressed.

Animals↗

PubMed1999

LH and FSH secretory responses to GnRH in normal individuals: a non-parametric deconvolution approach.

OBJECTIVE: To reconstruct the instantaneous secretion rate (ISR) of LH and FSH after GnRH administration in normal volunteers using non-parametric deconvolution, and to derive a direct integration formula to evaluate the amount of LH and FSH secreted during the first 60 min after the stimulus. DESIGN AND METHODS: First, the deconvolution method was validated in vivo by reconstructing doses ranging from 7.5 IU to 75 IU injected in three healthy adult volunteers whose endogenous LH had previously been downregulated by pretreating them, 3-4 weeks earlier, with 3.75 mg GnRH agonist i.m. Then, 40 healthy adult male volunteers were tested with a single 100 microg GnRH bolus, administered at 0 min. LH and FSH concentrations were determined at -30, 0, 15, 30, 45, 60, 90, and 120 min. RESULTS AND CONCLUSIONS: The validation study, conducted over a 10-fold range of doses, demonstrated that non-parametric deconvolution provided a reasonably accurate estimate of the amount of hormone entering the circulation. Applying deconvolution to the LH and FSH responses to GnRH, the ISRs of both hormones were shown to have a similar pattern, with a clearly delimited pulse after the GnRH bolus. In conjunction with earlier analyses of estimates of GHRH-stimulated GH secretion, we conclude that secretagogues evoke discrete LH, FSH, and GH secretory bursts of about 60 min total duration, despite markedly unequal (glyco-)protein hormone half-lives (18-500 min). With respect to the assessment of total hormone release during the first 60 min after the stimulus, the integration formula provided a reliable approximation of the result obtained by deconvolution, and had a negligible dependence on the samples at times 90 and 120 min.

Adult↗

PubMed2002

Mapping the distribution of (90)Sr in teeth with a photostimulable phosphor imaging detector.

The present communication describes the technical aspects of the first application of an imaging plate for visualization of (90)Sr deposited in human teeth. The teeth were obtained from Techa River area residents who were exposed as a result of releases of radioactivity into the Techa River by the first Soviet nuclear plant Mayak in the early 1950s. The investigations form the basis for an experimental procedure for accurate mapping of the distribution of (90)Sr in teeth with an imaging plate. This new method can be used as an individual indicator of radionuclide intake. Its advantages are its high sensitivity (0.02 Bq/g mm(-2) of (90)Sr), it ability to examine small detectable cross-sectional areas of dental tissue (dentin) contaminated with (90)Sr (from 0.01 mm(2)), the nondestructive method of analysis, and the simplicity of use. The combined application of this method with EPR tooth biodosimetry can provide more accurate dose reconstruction and may lead to more effective radiation risk assessment.

Calibration↗

PubMed2005

Stability of chromosome aberrations in the blood lymphocytes of astronauts measured after space flight by FISH chromosome painting.

Follow-up measurements of chromosome aberrations in the blood lymphocytes of astronauts were performed by FISH chromosome painting at various intervals from 5 months to more than 5 years after space flight and compared to preflight baseline measurements. For five of the six astronauts studied, the analysis of individual time courses for translocations revealed a temporal decline of yields with half-lives ranging from 10 to 58 months. The yield of exchanges remained unchanged for the sixth astronaut during an observation period of 5 months after flight. These results may indicate complications with the use of stable aberrations for retrospective dose reconstruction, and the differences in the decay time may reflect individual variability in risk from space radiation exposure.

Astronauts↗

PubMed2006

Estimating historical radiation doses to a cohort of U.S. radiologic technologists.

Data have been collected and physical and statistical models have been constructed to estimate unknown occupational radiation doses among 90,000 members of the U.S. Radiologic Technologists cohort who responded to a baseline questionnaire during the mid-1980s. Since the availability of radiation dose data differed by calendar period, different models were developed and applied for years worked before 1960, 1960- 1976 and 1977-1984. The dose estimation used available film-badge measurements (approximately 350,000) for individual cohort members, information provided by the technologists on their work history and protection practices, and measurement and other data derived from the literature. The dosimetry model estimates annual and cumulative occupational badge doses (personal dose equivalent) for each technologist for each year worked from 1916 through 1984 as well as absorbed doses to organs and tissues including bone marrow, female breast, thyroid, ovary, testes, lung and skin. Assumptions have been made about critical variables including average energy of X rays, use of protective aprons, position of film badges, and minimum detectable doses. Uncertainty of badge and organ doses was characterized for each year of each technologist's working career. Monte Carlo methods were used to generate estimates of cumulative organ doses for preliminary cancer risk analyses. The models and predictions presented here, while continuing to be modified and improved, represent one of the most comprehensive dose reconstructions undertaken to date for a large cohort of medical radiation workers.

Adolescent↗

PubMed2002

Biological dosimetry using human interphase peripheral blood lymphocytes.

Conventional metaphase-spread chromosome-aberration-based biodosimetry techniques for radiation dose assessment, although robust, are laborious and time consuming. The molecular cytogenetic laboratory of the Armed Forces Radiobiology Research Institute is developing simple and rapid interphase-based cytological assays that will be applicable to a broad range of radiation exposure scenarios. These assays include analysis of chromosome aberrations (premature chromosome condensation-fluorescence in situ hybridization assay) and mitochondrial DNA mutations (mtDNA4977 deletion assay) using resting human peripheral blood lymphocytes. The dose-effect relationship for radiation-induced aberrations involving chromosome 1 after 24 hours of repair at 37 degrees C in resting human peripheral blood lymphocytes was studied using fluorescence in situ hybridization after chemical induction of premature chromosome condensation as previously explained. In the present study, we examined whether gamma irradiation in the range of 0 to 7.5 Gy induces a dose-dependent increase in aberrations manifested as "excess spots." The number of excess spots per cell, reflecting aberrations involving chromosome 1, increased from 0.035 at 0.5 Gy to 0.236 at 7.5 Gy. This observed dose-effect relationship was fit with a nonlinear power model. This technique may be extended to the study of radiation-induced translocations in interphase cells for retrospective dose reconstruction. With a recently developed in situ polymerase chain reaction method to detect and quantify mtDNA deletion in interphase cells after radiation exposure in cultured human peripheral blood lymphocytes, 90% to 95% of cells are analyzable. We discuss the potential use of the mtDNA deletion assay in biological dosimetry applications. Interphase-based cytological assays may eliminate some inherent problems associated with metaphase-spread-based assays. These problems involve (1) the limited number of analyzable cells containing chromosome aberrations, which is due to various factors including radiation-induced cell death and delay in cell cycle progression into mitosis, and (2) the requirements for radiation cytogenetics expertise and tedious labor to manually score chromosome aberrations.

Chromosome Aberrations↗

PubMed2002

Genetic instability in peripheral blood lymphocytes of Chernobyl clean-up workers.

The group of clean-up workers involved in the liquidation of the consequences of the major accident at the Chemobyl nuclear power plant (CNPP) was exposed to high doses of radiation. In this review, we summarize the results of a long-term study of the cytogenetic status of CNPP clean-up workers. The data revealed different trends of the parameters of the cytogenetic status in the course of the study. The results of biological dose reconstruction, based on the frequency of mutant T-helper cells, are discussed.

DNA Damage↗