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PubMed1993

Small intestinal biopsy in children with coeliac disease: measurement of radiation dose and analysis of risk.

To verify the diagnosis of coeliac disease in childhood, three consecutive small intestinal biopsies are performed under fluoroscopic control. To assess the amount of radiation dose absorbed during biopsy, dose measurements were performed both in patients and in a phantom model. These measurements were used for a theoretical assessment of cancer risk and shortening of life due to radiation exposure. The cancer excess lifetime mortality risk (CELMR) was 0.001, i.e. 1 case per 1000 children with a diagnosis of coeliac disease. The loss of life expectancy after three small intestinal biopsies in childhood was approximately 15% of the risk due to lifetime exposure to natural background radiation. These results should be compared with the reported increased risk of malignancy for undiagnosed coeliac disease in adult age. Although the excess risk of the biopsies was small, all efforts should be made to use a technique and equipment giving the least radiation dose.

Biopsy↗
PubMed2001

Optimization technique for a Prompt Gamma-ray SPECT collimator system.

Because background radiation in an irradiation room creates a problem with the PG-SPECT (Prompt Gamma-ray Single Photon Emission Computed Tomography) system, which evaluates the absorbed dose for the Boron Neutron Capture Therapy treatment, optimization of a collimator system was performed while taking the shielding of background gamma-rays into consideration. Assuming that a parallel-beam collimator is used, three parameters--the diameter of a hole, the length of the collimator, and the number of detectors (the number of holes of the collimator)--were selected for optimization. Because the combinations of these parameters are limitless, it is difficult to determine them simultaneously. Therefore, a statistically derived Optimization Criterion has been proposed to optimize these parameters. When the spatial resolution was 1 cm-FWHM (full width at half maximum), the optimal diameter of the collimator was 5.4 mm, the optimal length was 321 mm, and the optimal number of detectors was 31 x 31.

Boron Neutron Capture Therapy↗
PubMed1981

Garland Lecture. On the question of cancer induction by small X-ray doses.

There is no proven body of fact that establishes an increase in human cancer after low doses of x or gamma radiation such as those received environmentally, occupationally, or from medical diagnostic procedures; that is, radiation levels below about 10 rad (0.1 Gy). This paper reviews the principal low dose epidemiologic studies that have investigated possible cancer increases. The results of these studies are negative, equivocal, or, when positive, invalidated by methodologic defects or by inconsistency with the feasible carcinogenic effect of background radiation. Despite the lack of direct evidence however, it will never be possible to exclude a very small cancer risk from even the lowest radiation levels, primarily because of statistical limitations in the design of epidemiologic studies. Estimates of cancer risk from low levels of x or gamma ray exposure are therefore based on assumptions regarding the relation between cancer increases and radiation dose. The statistical uncertainties of the meager human data at low doses do not permit unique relations to be established. Nevertheless recent radiobiologic investigations of dose/effect relations for neoplasms in animal populations, for chromosomal damage in human cells, and for malignant transformation in cultured mammalian cell lines suggest that a linear-quadratic relation, when fitted to the human data, provides a reasonable and conservative basis for risk estimation.

Adult↗
PubMed1996

[Hereditary chromosome instability in the common vole (Microtus arvalis) from the region of the Kyshtym nuclear accident--fact or hypothesis?].

In bone marrow cells of common voles living within the Eastern Urals radioactive track (EURT) and adjacent area, the frequency of chromosomal aberrations was higher than in cells of control animals. In several animals, the proportion of aberrant cells was significantly higher; cells with multiple chromosomal lesions prevailed among the aberrant cells. Frequency of chromosomal aberrations did not depend on the absorbed dose of beta-radiation. Taking into account the radiation background in trapping sites, the level of cytogenetic damage in the animals studies should be considered unexpectedly high. Outside the EURT, two voles with mutant karyotypes were caught. It was hypothesized that carriers of hereditary chromosome instability appeared in the population studies as a result of exposure to ionizing radiation.

Animals↗
PubMedDate not supplied

[Effect of vitamin D3 on metabolic processes in rat erythrocytes under extreme factors].

The effects of vitamin D3 (as an ingredient of the preparation "Videchol") on the activity of some glycolysis enzymes (lactic dehydrogenase, LDH; pyruvate kinase PK; hexokinase HK) and of pentose phosphate shunt (glucose-6-phosphate dehydrogenase), and also on the changes of metabolites concentration levels: ATP, NAD+, pyruvate and lactate following the administration of the vitamin to the control group rats and animals irradiated by low rate ionizing radiation were established. "Videchol" administration leads to the of LDH activity decrease within 10 days, of HK activity within 20 days and to the decrease of PK activity within 5 and 20 days after the experiment beginning. In the low dose radiation conditions a reconnection of carbohydrates' metabolism from glycolisys into pentose phosphate pathway in the erythrocytes was observed. The administration of vitamin D3 as a component of the preparation "Videchol" following the low rate radiation background facilitates the normalization of LDG, PK and HK activities in comparison with the same parameters of only irradiated rats. The studies on LDH--reaction kinetics showed the redistribution of the LDH isozymes pattern with different K(m) means for pyruvate in the rats subjected to the joint action of low dose chronical radiation and "Videchol" occurred.

Animals↗
PubMed1997

[Estimation of radiation exposure and radiation risk for employees of a heart catheterization laboratory].

The staff at interventional radiological procedures is exposed to high levels of ionizing radiation. This applies especially to measures at cardiac catheterization laboratories. In this study the annual radiation exposure to the staff was estimated by measuring the dose rate under characteristic conditions. It could be shown that the resulting radiation exposure was strongly dependent on the radiation protection measures and is also dependent on the operation conditions of the x-ray-tube. The effective dose for the physician wearing a lead apron and thyroid shield was determined to about 1.7 mSv/a. Without a thyroid shield an effective dose of about 3.5 mSv/a resulted. This corresponds to approximately the natural background radiation of about 2.4 mSv/a in the Federal Republic of Germany. From the number of procedures performed we could derive an effective dose of approximately 1-2 microSv per application for the physician, averaged over all types of procedures. Further, it could be shown that the readings of the film badges, usually worn by the staff, underestimate the effective dose by approximately a factor of two. This is because the film badges do not include the contribution of the unshielded parts of the body to effective dose. From the estimated annual effective dose, a lifetime dose of 68 mSv was estimated for a 40-year working career. The corresponding lifetime risk for induced fatal cancer due to radiation exposure was determined to 0.3% applying the ICRP risk factor of 4 x 10(-2) Sv-1. Considering the NCRP recommendations for a safe occupation, working in a cardiac catheterization laboratory can be considered as safe when applying all radiation protection measures. However, changing the protection measures and modifying the parameters of the x-ray-tube can lead to strong changes of the radiation exposure and the resulting risk estimation.

Cardiac Catheterization↗
PubMed1991

Protection of human health from mixtures of radionuclides and chemical in drinking water.

This study was undertaken to develop a common scale for evaluating health risks from contaminated drinking water. For different agents, many unrealistic models of risk have been used. By intent, regulatory toxicology depends on "data-sparse, model-intensive" analogies from exotic animal genetics and novel exposures (NCRP 1989). The question is, does a risk evaluation so derived have any predictive validity? Absence of data prevents answer because regulatory toxicology rationalizes in step-by-step logic, which we call absolute (i.e., predicts cases of disease in a population). Absolute models ensure safety, but do so at the cost of realism. In contrast, we make relative comparisons in the manner of horsepower or RBE from radiation biology. All pollutants are assumed to contribute to toxic injury. Next, relative potencies are linked to the most credible standards. Thus, experience is transferred from well-studied chemicals to the new chemical by "data-intensive, model-sparse" methods. This logos provides much relative precision. Then, pollutants are compared with: (1) common foodstuffs, (2) ambient radiation background, or (3) utility-pure drinking water. Finally, an assessment is made for a waste disposal area.

Carcinogens↗
PubMed2006

Quality assurance of environmental gamma radiation monitoring in Slovenia.

Environmental gamma radiation monitoring established in Slovenia consists of a network of multifunctional gamma monitors (MFMs) based on pairs of Geiger-Müller counters and a network of measuring sites with high-sensitive thermoluminiscence dosemeters. The measuring points are evenly spread across Slovenia, located at the meteorological stations and more densely on additional locations around the Krsko NPP. The MFM network has a 2-fold function with one sensor used for the purpose of early warning system in near surroundings of the NPP and the other, more sensitive, for natural radiation monitoring. The paper summarises activities to establish quality assurance of the environmental gamma radiation measurements in Slovenia, with a critical view of the results in comparison with the international standards and recommendations. While the results of linearity and energy dependence tests were satisfying, on-field intercomparison showed that the inherent signal of one of the monitors (MFM) has to be taken into account in the range of environmental background radiation.

Air Pollution, Radioactive↗
PubMed1987

Cancer and leukemia risks after low level radiation--controversy, facts and future.

Quantification of delayed low dose radiation (LDR) effects is still controversial. The current concept of the shape of the dose-response curve, particularly at the very low levels, is derived primarily by extrapolation from high doses and is affected by economic, social and political implications of cancer yield. Evidence based on epidemiological studies of populations exposed to fallout, occupational, intrauterine or background LDR is limited, due to methodological drawbacks and the need for extremely large sample sizes. Nevertheless, recent data indicate that LDR-induced childhood leukemia and thyroid cancer may exceed the rates predicted on the basis of the linear quadratic curve. The high yield in utero and in early childhood could be associated with low cumulative load of background radiation, and a consequently more effective radiation increment. A long term follow up of children exposed to 90 mSv after scalp X-irradiation revealed a relative risk of 3.8 and an excess risk of about 1.08 per 1000 man-sievert per year for thyroid cancer. Application of these findings to the post-Chernobyl state of events suggests that an increment of up to 20% in thyroid cancer might occur in a population exposed to 5 mSv as an aftermath of a similar accident. Prediction of future risk estimates should therefore be made with alertness and an open mind.

Humans↗
PubMed2000

Practical applicability of field gamma-ray scintillation spectrometry in geophysical surveys

We discuss the problems and calibration procedures for a portable gamma-ray scintillation spectrometer for determinations of potassium, uranium and thorium concentration in rocks. Particular emphasis was given to the evaluation of the background radiation. The apparatus was tested in the field at two selected areas in NW Italy. We found appropriate sites which could be used as reference targets to frequently check the gamma-ray equipment. An area formed by serpentinitic rocks showed such a low measured radioactivity that it could be used as a reference for the local background effect. An anomalously high uranium amount against negligible potassium and thorium concentrations were found in outcrops of dolomitic rocks, which can be used to detect possible changes in the instrument calibration constants.

Journal Article↗
PubMed2006

Chemistry and cosmology.

The simplest elements, hydrogen and helium, offer a remarkably rich chemistry, which has controlled crucial features of the early evolution of the universe. Theoretical models of the origin of structure (stars, galaxies, clusters of galaxies, etc.) now incorporate this chemistry in some detail. In addition to the origin of structure, cosmologists are concerned with observational tests of competing world models. Primordial chemistry may give rise to some of the earliest departures from thermodynamic equilibrium in the universe. These effects may be observable as broad-band spectroscopic distortions of the cosmic background radiation, which otherwise exhibits a nearly perfect blackbody spectrum. The chemical history of the expanding universe is followed through a detailed calculation of the evolution of the abundances of H, H+, H-, H2, H2+, H3+, and other minor species. It is shown that continuous absorption by the small concentration of H- can produce a distortion in the cosmic background spectrum with a maximum at a frequency near nu/c = 9 cm-1 (wavelength 1.1 mm). The predicted effect lies only a factor of 5 below current limits. Its detection would provide an important test of our understanding of the recombination epoch of the universe.

Journal Article↗
PubMed1979

[The determination of the left ventrical volume curve without background correction and its validation by direct intercomparison with the ejection fractions as determined by biplane laevocardiography (author's transl)].

Background corrections applied on the left ventricular volume curve determined by the "gated blood pool"--method are based on an estimated rather than on a directly measured background. This imposes an uncertainty on the values determined from the volume curve, especially on the ejection fraction. A method which does not require background correction may be applied if all available measurement and evaluation facilities are utilized fully. High temporal and spatial resolution is of fundamental importance, permitting the exact determination of the time-dependent scintigraphic contour variations of the left ventricle during the mechanical action of the heart. A good criterion of the validity of the volume curves with respect to interfering background radiation is the ejection fraction calculated from these curves. The direct intercomparison of 10 ejection fractions obtained by an expanded "gated blood pool"-method, employing cardiac catheterization, immediately before a biplane laevocardiography demonstrated very good agreement. A small systematic underestimation of the ejection fraction by the nuclear method was observed. This understimulation shows that the influence of the true background is small if other interfering count rate contributions or methodical uncertainties are excluded systematically.

Angiography↗
PubMed2002

Health transitions, fast and nasty: the case of Marshallese exposure to nuclear radiation.

The concept of health transitions assumes that health status improves with the introduction of western medicine. In this paper I demonstrate that the health of the people of Rongelap, Marshall Islands, has undergone serious damage as a result of nuclear testing, and that women in particular have suffered unduly. Exposure to nuclear radiation over a period of almost fifty years has been recognised by US authorities as a major contributory cause to the high rates of cancers and birth defects suffered by the Rongelap people. Women's reproduction has been severely affected, as evidenced by the many stillbirths and small stature of children born alive. Two generations have been exposed to both background radiation and to radiation ingested with the local foods on which they rely in the absence of other food sources. Clean up has commenced only after this and other communities sought compensation from the United States. The Rongelap people will live with the effects of radiation for generations to come. This transition to ongoing health problems is thus a negative outcome of modern health transition.

Abnormalities, Radiation-Induced↗
PubMed2000

Application of EPR retrospective dosimetry for large-scale accidental situation.

Above 3000 tooth enamel samples, collected at population of radioactive contaminated territories after Chernobyl accident, the Chernobyl liquidators, the retired military of high radiation risk and the population of control radiation free territories were investigated by EPR spectroscopy method in order to obtain accumulated individual exposure doses. Results of EPR spectra measurements are stored in data bank; enamel samples are also stored in order to provide the possibility to repeat the measurements in future. Statistical analysis of results has allowed to detect the contribution into EPR signal in tooth enamel due to the action of the natural background radiation, and the radioactive contamination of territory. In general, the average doses of external exposure of the population obtained with EPR spectroscopy of teeth enamel are consistent with results based on other methods of direct and retrospective dosimetry. Essential exceeding of the individual doses above the average level within the population groups was observed for some persons. That gave the possibility to detect the individuals with overexposure, which were included into groups for medical monitoring.

Case-Control Studies↗
PubMed1994

Heavy ion and cosmic radiation effects in different targets of the Arabidopsis seed.

The seed embryo of Arabidopsis thaliana, the favorite plant of up-to-date molecular developmental biology, represents a valuable model system for space radiation research with heavy ions. For several years, densely ionizing particles have been available for basic studies in nuclear physics and radiation biology through special accelerators as well as through space flight missions. Because of the great variability of the available radiation spectra, the induced relative biological effect (RBE-value) has to be differentiated with respect to the effective charge (z) and the linear energy transfer (LET) deposited in a certain volume of matter, and to the biological targets which differ in size, structure and function. The results of comparative studies of 8 space flight experiments, here by example show increasing damage produced by single heavy ions and/or cosmic background radiation (protons, neutrons, X-rays). These results offer new prospects for molecular investigation of the RBE of heavy ions in space.

Arabidopsis↗
PubMed1984

A study of the performance of selected instrumentation for 133Xe personnel hazard measurements in nuclear medicine laboratories.

Past studies of others, as well as the authors' experiences in measuring 133Xe concentrations in nuclear medicine laboratories, have indicated that significant and somewhat unpredictable levels of personnel exposure to 133Xe may occur in such facilities. Previous studies by the authors indicate that most personnel dosimeters do not respond to 133Xe radiations adequately for use in personnel protection applications. This indicates the need for using some types of 133Xe measuring devices for determining that 133Xe personnel exposure limits (CFR82) are not exceeded for workers in nuclear medicine laboratories. Based on these needs, selected instruments for this application were evaluated. These include four continuous 133Xe air-concentration monitors and nine survey instruments. Responses of the instruments were measured in both normal background radiation conditions and in a 133Xe atmosphere containing known concentrations of 133Xe. Based on these measurements, minimum detectable activity values were calculated for various measurement conditions. It was concluded that three of the four continuous 133Xe air-concentration monitors were suited for general applications in indicating long-term integrated personnel exposure to 133Xe. Two of the nine survey instruments evaluated were, under certain conditions, capable of measuring 133Xe concentrations under 0.015 maximum permissible concentration (MPC).

Air Pollutants↗
PubMed1986

Embryogenesis and organogenesis of Carausius morosus under spaceflight conditions.

The influence of cosmic radiation and/or microgravity on insect development was studied during the 7 day German Spacelab Mission D1. Eggs of Carausius morosus of five stages differing in sensitivity to radiation and in capacity to regeneration were allowed to continue their development in the BIORACK 22 degrees C incubator, either at microgravity conditions or on the 1 g reference centrifuge. Using the Biostack concept--eggs in monolayers were sandwiched between visual track detectors--and the 1 g reference centrifuge, we were able to separate radiation effects from microgravity effects and also from combined effects of these two factors in space. After retrieval, hatching rates, growth kinetics and anomaly frequencies were determined in the different test samples. The early stages of development turned out to be highly sensitive to single hits of cosmic ray particles as well as to the temporary exposure to microgravity during their development. In some cases, the combined action of radiation and microgravity even amplified the effects exerted by the single parameters of space. Hits by single HZE particles caused early effects, such as body anomalies, as well as late effects, such as retarded growth after hatching. Microgravity exposure lead to a reduced hatching rate. A synergistic action of HZE particle hits and microgravity was established in the unexpectedly high frequency of anomal larvae. However, it cannot be excluded, that cosmic background radiation or low LET HZE particles are also causally involved in damage observed in the microgravity samples.

Abnormalities, Radiation-Induced↗
PubMed2001

Measurements of radiation near an atomic spectral line from the interaction of a 30 GeV electron beam and a long plasma.

Emissions produced or initiated by a 30-GeV electron beam propagating through a approximately 1-m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creation of plasma, and estimates of neutral and plasma density have been extracted. Increases in visible background radiation, consistent with increased plasma recombination emissions due to dissipation of wakefields, were simultaneously measured.

Journal Article↗