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Uranium mining can cause environmental impacts on non-human biota around mine sites. Because of this, the reduction in non-human biota exposure becomes an important issue. Environmental radioprotection results from the evolution of human radioprotection; it is based on dose rate to non-human biota and uses, as a biological target, and has harmful effects on populations. In the present study, a flooded impoundment created following dam construction in a uranium mine plant undergoing decommissioning was investigated. Internal dose rates due to activity concentration of natural uranium (Unat) and 232Th in omnivorous, phytophagous, and carnivorous fish species were estimated. Radionuclide activity concentrations were obtained by spectrophotometry with arsenazo III in the visible range. The dose rate contribution of 232Th was lower than that of Unat. There were no differences between the internal dose rates to studied fish species due to 232Th, but there were differences for Unat. A dose rate of 2.30·10–2 µGy∙d−1 was found due to the two studied radionuclides. Although this value falls below the benchmark for harmful effects, it is important to acknowledge that the assessment did not account for other critical radionuclides from uranium mining, which also contribute to the internal dose. Moreover, the study did not assess external doses. As a result, the possibility cannot be excluded that dose rates at the study area overcome the established benchmarks for harmful effects. [ABSTRACT FROM AUTHOR]

Estimation of Specific Absorption Rate levels in a typical bunch of Sapodilla fruits is presented. Detailed discussion on their variations, due to the existing disparity among the electromagnetic standards is presented in a quantitative manner. The work includes dielectric properties characterization of the fruit specimen and the modelling of a typical fruit bunch according to their dielectric properties for the simulation-based investigations in order to gauge the Specific Absorption Rate levels based on the exposure standards. A typical geometric shape of the fruit bunch, modelled only under the most practical considerations – is also taken, in order to replicate the exact natural scenario, where the fruits or the other plant tissues are irradiated with electromagnetic exposures from the mobile towers and other Radio Frequency energy sources. The variations in the estimated Specific Absorption Rate levels calculated under different electromagnetic standards prescribed globally are seen to be substantial and the records are presented in detail in this article. Rigorous simulation works are carried out, to ensure accurate comparison between the estimated Specific Absorption Rate levels. Two global and two national electromagnetic standards are taken for the comparisons; both occupational and public exposure standards are considered. Five different frequencies of mobile operations are also considered as possible RF exposure sources in this work, for the investigations. The variation existing between the estimated Specific Absorption Rate levels based on the different standards in each of the frequencies - suggests a critical evaluation of the status quo and calls for the need of maintaining a global homogeneity among the existing Radio Frequency exposure regulations. [ABSTRACT FROM AUTHOR]

In international guidelines for human protection from radio-frequency (RF) electromagnetic fields, the specific absorption rate (SAR) averaged over 6 min and 10 g of tissue is used as a physical quantity to prevent excess local temperature rise. The resultant SAR restriction has been set to avoid potential adverse health effects due to the temperature elevation resulting from RF energy absorption. In the public consultation version of the upcoming ICNIRP RF guidelines (July 10, 2018), a specific absorption (SA) limit was set to avoid heating from brief exposures (shorter than 6 min). However, to the best of our knowledge, no prior research has evaluated the temperature rise for single/multiple pulses with energy equivalent to the 6-min exposure SAR restriction for continuous waves. This paper computed the temperature rise for brief pulse exposures based on bioheat computations. We first confirmed that the peak temperature rise for a pulse with SA corresponding to occupational exposure exceeds the steady-state temperature rise for temporally uniform continuous wave exposure. We then proposed the SA limit from a regression curve that is dependent on the duration of brief exposure to RF pulse(s). The temperature rise in a multilayer cube and an anatomical human model were also computed for exposures to multiple pulses. The temperature rise from multiple pulses satisfying the formula was found to be below the relevant threshold level. The SA based on this regression curve can be used as a metric to prevent excess temperature rise for different brief exposure scenarios below 6 min.

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and the IEEE C95.1 standard are currently under revision. In the guidelines/standard, the dominant effect for electromagnetic field exposures at frequencies above 100 kHz is the thermal effect. The whole-body-and 10g-averaged specific absorption rates (SARs), which are surrogates for core and local temperature elevations, respectively, are set as metrics for exposure evaluation. The external field strengths or incident power density, corresponding to the limit for SARs, are also used as metrics for practical compliance purposes. Although the limits for the SARs are identical amongst the guidelines/standard, the limits for the external field strengths differ by a factor of 7.4–12.9 in an intermediate frequency range (100 kHz–100 MHz). Due to the fact that the standard/guidelines were published before the computation with anatomical human models was available, it is worth revisiting the relationship between the SARs and external field strengths by computations using the human models. Intercomparison using different numerical codes was also performed to verify the results. For the main finding, as expected, the 10g-averaged SAR was a less restrictive factor for whole-body exposure over the frequencies considered in this paper. It was also found that the relationship between SARs and external field strength was satisfied, but was more conservative in the ICNIRP guidelines, whereas there were slight discrepancies below 30 MHz in the IEEE standard. The computational results would be useful for revising the permissible external field strength based on scientific results.

An understanding of radiation dose and the anticipated risk to the patient is an important aspect of ordering radiological imaging studies responsibly. It is especially true for the pediatric practitioner because children are more vulnerable to the biological effects of radiation, such as radiosensitivity, longer lifetime years, and higher cellular mitotic activity. The use of fluoroscopy and computed tomography is commonplace in the practice of craniofacial surgery, but often dose reports from varied investigations are not directly comparable, and the risk of patient harm from the investigation is unclear. This article presents the fundamentals of radiation, dose, and risk as it applies to radiological imaging and also introduces our low dose craniofacial computed tomography protocol. [ABSTRACT FROM AUTHOR]

A versatile and straightforward human body model, comprising simple geometric structures, is consistently developed in this study for the precise electromagnetic field exposure assessment owing to mediated lightning strikes. The proposed model incorporates a realistic set of frequency‐dependent media, approximated by a 4‐Cole‐Cole scheme, while every body part is considered to be occupied by the most dominant medium. For the reliable evaluation of all related electromagnetic quantities, the featured implementation is systematically discretised by means of an efficient finite‐difference time‐domain algorithm and all results are compared to those of a circuit‐based approach, simulated via an electronic circuit software. Moreover, to minimise comparison errors, the most critical human body dimensions are carefully optimised. Finally, the model, so constructed, is employed for the study of a side flash impact and the investigation of a lethal electric discharge possibility through the disruptive effect technique. The benefits of the proposed realisation in the successful prediction of mediated lightning effects are thoroughly validated in terms of various real‐world scenarios, which, among others, reveal that the impact on humans is inversely proportional to its distance from the stroked object. [ABSTRACT FROM AUTHOR]

Purpose: The use of sophisticated dose calculation procedure in modern radiation therapy treatment planning is inevitable in order to account for complex treatment fields created by multileaf collimators (MLCs). As a consequence, independent volumetric dose verification is time consuming, which affects the efficiency of clinical workflow. In this study, the authors present an efficient adaptive beamlet-based finite-size pencil beam (AB-FSPB) dose calculation algorithm that minimizes the computational procedure while preserving the accuracy. Methods: The computational time of finite-size pencil beam (FSPB) algorithm is proportional to the number of infinitesimal and identical beamlets that constitute an arbitrary field shape. In AB-FSPB, dose distribution from each beamlet is mathematically modeled such that the sizes of beamlets to represent an arbitrary field shape no longer need to be infinitesimal nor identical. As a result, it is possible to represent an arbitrary field shape with combinations of different sized and minimal number of beamlets. In addition, the authors included the model parameters to consider MLC for its rounded edge and transmission. Results: Root mean square error (RMSE) between treatment planning system and conventional FSPB on a 10 × 10 cm² square field using 10 × 10, 2.5 × 2.5, and 0.5 × 0.5 cm² beamlet sizes were 4.90%, 3.19%, and 2.87%, respectively, compared with RMSE of 1.10%, 1.11%, and 1.14% for AB-FSPB. This finding holds true for a larger square field size of 25 × 25 cm², where RMSE for 25 × 25, 2.5 × 2.5, and 0.5 × 0.5 cm² beamlet sizes were 5.41%, 4.76%, and 3.54% in FSPB, respectively, compared with RMSE of 0.86%, 0.83%, and 0.88% for AB-FSPB. It was found that AB-FSPB could successfully account for the MLC transmissions without major discrepancy. The algorithm was also graphical processing unit (GPU) compatible to maximize its computational speed. For an intensity modulated radiation therapy (~12 segments) and a volumetric modulated arc therapy fields (~90 control points) with a 3D grid size of 2.0 × 2.0 × 2.0 mm³, dose was computed within 3-5 and 10-15 s timeframe, respectively. Conclusions: The authors have developed an efficient adaptive beamlet-based pencil beam dose calculation algorithm. The fast computation nature along with GPU compatibility has shown better performance than conventional FSPB. This enables the implementation of AB-FSPB in the clinical environment for independent volumetric dose verification. [ABSTRACT FROM AUTHOR]

Purpose: Benign computed tomography (CT) changes due to radiation induced lung injury (RILI) are common following stereotactic ablative radiotherapy (SABR) and can be difficult to differentiate from tumor recurrence. The authors measured the ability of CT image texture analysis, compared to more traditional measures of response, to predict eventual cancer recurrence based on CT images acquired within 5 months of treatment. Methods: A total of 24 lesions from 22 patients treated with SABR were selected for this study: 13 with moderate to severe benign RILI, and 11 with recurrence. Three-dimensional (3D) consolidative and ground-glass opacity (GGO) changes were manually delineated on all follow-up CT scans. Two size measures of the consolidation regions (longest axial diameter and 3D volume) and nine appearance features of the GGO were calculated: 2 first-order features [mean density and standard deviation of density (first-order texture)], and 7 second-order texture features [energy, entropy, correlation, inverse difference moment (IDM), inertia, cluster shade, and cluster prominence]. For comparison, the corresponding response evaluation criteria in solid tumors measures were also taken for the consolidation regions. Prediction accuracy was determined using the area under the receiver operating characteristic curve (AUC) and two-fold cross validation (CV). Results: For this analysis, 46 diagnostic CT scans scheduled for approximately 3 and 6 months posttreatment were binned based on their recorded scan dates into 2-5 month and 5-8 month follow-up time ranges. At 2-5 months post-treatment, first-order texture, energy, and entropy provided AUCs of 0.79-0.81 using a linear classifier. On two-fold CV, first-order texture yielded 73% accuracy versus 76%-77% with the second-order features. The size measures of the consolidative region, longest axial diameter and 3D volume, gave two-fold CV accuracies of 60% and 57%, and AUCs of 0.72 and 0.65, respectively. Conclusions: Texture measures of the GGO appearance following SABR demonstrated the ability to predict recurrence in individual patients within 5 months of SABR treatment. Appearance changes were also shown to be more accurately predictive of recurrence, as compared to size measures within the same time period. With further validation, these results could form the substrate for a clinically useful computer-aided diagnosis tool which could provide earlier salvage of patients with recurrence. [ABSTRACT FROM AUTHOR]

Radiation shielding is of primary importance in the planning of new interplanetary manned missions, and the ISS represents the largest laboratory for radiation shielding in space ever built. The ISS radiation environment has been thoroughly characterised by the Monte Carlo-based high-energy physics toolkit Geant4. It has been found that the ISS structure is quite effective at shielding from most forms of radiation, largely due to its internal arrangement. The internal environment found is consistent with literature values and astronaut dosimetry, and results indicate that the internal arrangement of a spacecraft may be the key to the radiation environment within it. Simulation results are also presented for the interplanetary case, including detailed comparisons with other codes. Guidelines for interplanetary manned mission design are presented using these findings. [ABSTRACT FROM AUTHOR]

In recent years, people have been exposed to many kinds of electromagnetic fields (EMFs) generated by domestic electrical appliances and mobile telecommunication devices. There is increasing public concern regarding the health risks of radio-frequency (RF) radiation, particularly that produced by mobile phones. Concern regarding the potential risks of exposure to EMFs has led to many epidemiological investigations, but the effects of EMF exposure on human and other mammalian cells are still unclear. Cellular studies of the effects of RF EMFs have been conducted more often than epidemiological and animal studies. This review provides a summary of the potential cellular effects of RF fields, including those generated by cell phones and their base stations. In vitro studies of the effects of RF fields can mainly be classified into those examining genotoxic and nongenotoxic effects. Genotoxic effects include DNA strand breaks, micronucleus formation, mutation, and chromosomal aberration, i.e., changes involving damage to DNA. Nongenotoxic effects refer to changes in cellular functions, including cell proliferation, signal transduction, and gene expression (mRNA and protein). The results of most recent studies show no marked effects of RF exposure at the cellular and genetic levels. However, some studies have suggested RF effects, and these results require further investigation. As the wireless power transfer technologies are gaining more popularity, it is important that the engineering community participate in the health assessment study with medical and biological research groups. Since the electromagnetic environment due to future wireless power technologies continues to increase, biologists also have to promote the research assessment utilizing advanced technologies in the life sciences. This review paper attempts to provide an insight on the cellular and molecular responses to the RF electromagnetic fields and the understanding of such biological impacts are important for wireless power technology applications. [ABSTRACT FROM PUBLISHER]

Recent interest and current optimism regarding battery-charging wireless power-transfer technology are driven by the ubiquity of cell phones and other mobile communication devices. In some ways, this is to make a dream come true: a truly wireless mobile or portable communication device, completely free from being tethered in any way. The concept of wireless power transfer is not new, even for charging batteries. Cellular service users and customers may be annoyed by or do not want to be bothered with having to plug the mobile device into an electrical outlet. If this is true - as appears to be the case - then time may well provide a fix to the grief. Aside from not having to plug in the mobile phone or laptop, a more probable cause for the sudden interest in battery charging through wireless power transfer may come from the potential for mobile communication devices to get their electrical power the same way they get their data. Unlike wireless communication uses, the level of transmitted electromagnetic power required for large-scale or commercial implementation of wireless power transfer could be substantial. A key feature of the system design and research effort should be consideration of biological effects and human safety. [ABSTRACT FROM AUTHOR]

An ion microbeam is a very narrow beam of charged particles, typically protons, alpha particles, or heavier, of micrometer/submicrometer size, corresponding to cellular/subcellular dimensions. Together with integrated techniques for locating live cellular or subcellular targets, they allow rapid sequential irradiation of these targets. This review covers both the technology involved in modern single-cell microbeams, as well as some current applications. The recent explosion of interest in microbeams was initially driven by interest in the domestic radon problem, in which target cells are exposed either to zero or one alpha particle. Microbeams allow cells to be individually irradiated with exact numbers of particles. As microbeams were built, refined, and used, the biological questions that were addressed with them have considerably broadened, to encompass many aspects of damage signal transduction. Two areas in particular have attracted much interest: One is the use of microbeams to address the sensitivity Of subcellular targets, such as the cytoplasm or mitochondria. The other reflects the ability of the microbeam to irradiate some cells, but not others, allowing a direct investigation of the so-called bystander effect, where signals from irradiated cells can apparently cause biological responses in neighboring unirradiated cells. [ABSTRACT FROM AUTHOR]

This paper studies on tumor incidence in mice exposed to GSM cell-phone radiation. The first study of lymphomas in female Emu_Pim1 transgenic mice using frequencies and modulations specific to cellular mobile phones was conducted in Australia in which the incidence was shown to be significantly higher (odds ratio, OR = 2.4) in the exposed mice (43%) than in the sham controls (22%) [M.H. Repacholi et al., 1997] following 18 months of two 30-min periods per day exposure to 900-MHz plane-wave radiation repeated at 217 Hz [signals that mimic global system for mobile communication (GSM) digital mobile phones]. [ABSTRACT FROM PUBLISHER]

A characterization of the Galactic Cosmic Ray (GCR) induced radiation environment on-board Columbus and the International Space Station (ISS) has been carried out using the Geant4 Monte Carlo particle transport toolkit and detailed geometry models of Columbus and ISS. Dose and dose equivalent rates, as well as penetrating particle spectra are presented. Simulation results indicate that the major part of the dose rates due to GCR protons are associated with secondary particles produced in the hull of ISS. Neutrons contribute about 15% of the GCR proton dose equivalent rate and mesons about 10%. More than 40% of the simulated GCR proton dose and dose equivalent rates are due to protons in the energy range above 10 GeV. Protons in the energy range above 50 GeV contribute only 5% to the dose rates. The total simulated dose and dose equivalent rates at solar maximum are 63 μGy/d and 123 μSv/d, respectively. The dose equivalent rate underestimates measurements made during the 2001 solar maximum. The discrepancy can be attributed to deficiencies in hadronic ion-nuclei interaction models for heavy ions and to the lack of such models above 10 GeV/N in Geant4. [ABSTRACT FROM AUTHOR]

Abstract: The influence of geometry model approximations on Geant4 Monte Carlo simulation results of the radiation environment on-board the Columbus module of the International Space Station (ISS) has been investigated. Three geometry models of Columbus with different levels of detail and a geometry model of ISS have been developed. These geometries have been used for Geant4 simulations of the radiation environment inside Columbus induced by trapped protons and Galactic Cosmic Ray protons. Simulated dose rates and particle spectra on-board Columbus for each of the three Columbus models, with or without the ISS geometry model included, are presented and compared. From comparisons of simulated dose rates and particle spectra for the three different geometry models it was found that the most detailed geometry model (750 volumes) produced results similar to a much less detailed model (23 volumes). The most detailed geometry model was concluded to be a sufficiently detailed approximation of the physical Columbus for the purpose of proton induced space radiation studies. The simulated dose rates are compatible with measurements on-board the ISS. The simulation results also show that an increase in shielding thickness decreases the simulated dose rate induced by trapped protons. For Galactic Cosmic Ray protons the dose rate remains unchanged or is slightly increased. [Copyright &y& Elsevier]

A detailed characterization of the trapped-proton-induced radiation environment on board Columbus and the Inter- national Space Station (ISS) has been carried out using the Geant4 Monte Carlo particle transport toolkit. Dose and dose equivalent rates, as well as penetrating particle spectra are presented. These results are based on detailed Geant4 geometry models of Columbus and ISS, comprising a total of about 1000 geometry volumes. Simulated trapped-proton dose rates are found to be strongly dependent on ISS altitude. Dose rates for different locations inside the Columbus cabin are presented, as well as for different models of the incident trapped-proton flux. Dose rates resulting from incident anisotropic trapped protons are found to be lower than, or equal to, those of omnidirectional models. The anisotropy induced by the asymmetric shielding distribution of Columbus/ISS is also studied. The simulated trapped-proton dose (equivalent) rates, averaged over different locations inside Columbus, are 120 µGy/d (154 µSv/d) and 79 µGy/d (102 µSv/d) for solar minimum and maximum conditions according to AP8 incident proton spectra and an ISS orbit of 380 km. The solar maximum dose rates are found to be of the same order as measurements in other modules in the present ISS. [ABSTRACT FROM AUTHOR]

Due to the increasing interest in millimeter-wave (MMW) applications for wireless communication systems, the investigation of their potential biological effects is of utmost importance. In this paper, we report experimental results of the study of interactions between low-power radiation at 60 GHz and artificial models of biological membranes. In the first part of this study, we demonstrate an increase of superficial pressure of phospholipid monolayers during MMW exposure. Two of the most prominent in quantity lipid constituents of biological membranes, dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine, are considered. The role of different radiation parameters, namely, power density, polarization, amplitude modulation, permanent, and discontinuous exposure, is discussed. The results have proved to be reproducible in independent experiments. In the second part of this study, through atomic force microscopy analysis, we investigate the influence of MMW radiation on the microdomain distribution in mixed phospholipid monolayers with phase separation. No significant modifications are observed in microdomain distribution after 5 h of exposure. The main outcomes of this study lead to the conclusion that short-term low-power MMW exposures result in an increase of lateral pressure of the phospholipid monolayer, but their influence is not sufficiently strong to disturb phospholipid microdomain organization in biomembranes [ABSTRACT FROM PUBLISHER]

This column discusses the new IEEE standard in radio frequency exposure. This column examines some of the more salient aspects applicable to mobile communication. The author plans to cover the other differences at a future date. [ABSTRACT FROM PUBLISHER]

Geant4 Radiation Analysis for Space (GRAS) is a modular, extendable tool for space environment effects simulation. Analyses include cumulative ionizing and NIEL doses, effects to humans, charging, Huence and transient effects in three-dimensional geometry models. [ABSTRACT FROM AUTHOR]

The Dose Estimation by Simulation of the ISS Radiation Environment (DESIRE) project aims to accurately calculate radiation fluxes and doses to astronauts inside the European Columbus module of the International Space Station using Geant4. Since Geant4 has not been previously used for this type of application it needs to be validated. This will be followed by a detailed evaluation of the incident radiation fields on ISS and culminate with the geometry modeling and full-scale flux and dose simulations for Columbus. Geant4 validation studies and comparisons to other tools are presented. These concern the angle and energy distributions of particles leaving irradiated targets and of energy depositions in the targets. Comparisons are made between simulations using different Geant4 physics models, experimental data, and other particle transport programs. Geant4 using the "Binary Cascade" model for inelastic nucleon reactions performs very well in these comparisons, but some issues with other models remain to be resolved if they are to be used for space radiation shielding applications. Results of Geant4 simulations of the transport of some relevant radiation field components through the hull of a simplified model of Columbus are also presented. [ABSTRACT FROM AUTHOR]

Most of our knowledge concerning the biological effects of radio frequency (RF) radiation from wireless communication devices has come out of investigations conducted using experimental animals, such as rats, mice, etc. When it comes to the impact of RF radiation on human health and safety, epidemiology can play a pivotal role because it is a study of the distribution of disease and its determinants in human populations. To examine if exposure to wireless communication radiation is involved in cancer induction and promotion, it is necessary to collect data from people with similar backgrounds, other than RF exposure [ABSTRACT FROM PUBLISHER]

New phantom models that can simulate the effect of electromagnetic waves on human tissues have been developed. These phantom models can be designed to fit a wide range of complex permittivities by using two types of carbon fiber within a silicone rubber base. Tissues with low water content, such as fat and bone, and tissues with high water content, such as skin and muscle, can both be modeled using the phantom models discussed in this paper. When using conventional phantom model materials, care must be taken to prevent decomposition and dehydration during storage. The materials used for these new phantom models do not dry out and can be used repeatedly with reliable results. [ABSTRACT FROM AUTHOR]

A broadband calibration procedure for E-field probes that minimizes the overall uncertainties inherent in E-field measurements in lossy dielectric liquids has been developed. The analysis of the calibration requirements shows that probes that are symmetrical with respect to their axis greatly facilitate accurate calibration, since the calibration procedure can be divided into several discrete steps. Such a procedure is presented and analyzed with respect to its uncertainties. Absolute calibration is performed at three frequency bands utilized in Europe for mobile communications (450 MHz, 900 MHz, and 1.8 GHz) and in different tissue-simulating liquids. The parameters obtained are verified by numerical simulations of the probe in the surrounding media. Such simulations allow the assessment of some of the calibration parameters with sufficient accuracy in cases where the experimental determination would be too tedious and time consuming. [ABSTRACT FROM AUTHOR]

Nonbilayer structures, as lysophospholipid micelles, can be produced in membranes by gamma irradiation. Interesting information on the gamma-ray effect on the lysophospholipid organization can be obtained by spin-label techniques. Variations of the TEMPO partition are appreciable, particularly in the range of the lipid thermotropic transition, even from relatively low doses. With increasing dose this transition becomes more and more complex and wider, according to the previous thermodinamic analysis. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasing clinical use of low-energy photon and electron sources (below few tens of keV) has raised concerns on the adequacy of the existing approximation of an energy-independent radiobiological effectiveness. In this work, the variation of the quality factor (Q) and relative biological effectiveness (RBE) of electrons over the low-medium energy range (0.1 keV–1 MeV) is examined using several microdosimetry-based Monte Carlo methodologies with input data obtained from Geant4-DNA track-structure simulations. The sensitivity of the results to the different methodologies, Geant4-DNA physics models, and target sizes is examined. Calculations of Q and RBE are based on the ICRU Report 40 recommendations, the Kellerer-Hahn approximation, the site version of the theory of dual radiation action (TDRA), the microdosimetric kinetic model (MKM) of cell survival, and the calculated yield of DNA double strand breaks (DSB). The stochastic energy deposition spectra needed as input in the above approaches have been calculated for nanometer spherical volumes using the different electron physics models of Geant4-DNA. Results are normalized at 100 keV electrons which is here considered the reference radiation. It is shown that in the energy range ~50 keV-1 MeV, the calculated Q and RBE are approximately unity (to within 1–2%) irrespective of the methodology, Geant4-DNA physics model, and target size. At lower energies, Q and RBE become energy-dependent reaching a maximum value of ~1.5–2.5 between ~200 and 700 eV. The detailed variation of Q and RBE at low energies depends mostly upon the adopted methodology and target size, and less so upon the Geant4-DNA physics model. Overall, the DSB yield predicts the highest RBE values (with RBE m a x ≈ 2.5) whereas the MKM the lowest RBE values (with RBE m a x ≈ 1.5). The ICRU Report 40, Kellerer-Hahn, and TDRA methods are in excellent agreement (to within 1–2%) over the whole energy range predicting a Q m a x ≈ 2. In conclusion, the approximation Q = RBE = 1 was found to be valid only above ~50 keV whereas at lower energies both Q and RBE become strongly energy-dependent. It is envisioned that the present work will contribute towards establishing robust methodologies to determine theoretically the energy-dependence of radiation quality of individual electrons which may then be used in subsequent calculations involving practical electron and photon radiation sources. • The radiation quality (Q, RBE) of low-medium energy electrons is studied by microdosimetry-based methods. • Calculations are based on Geant4-DNA track-structure simulations at the nanometer scale. • The approximation of constant radiation quality was found valid only between 50 keV and 1 MeV. • At sub-keV energies the Q and RBE exhibit a strong energy-dependence reaching a maximum value between 1.5 and 2.5. [ABSTRACT FROM AUTHOR]

A recent report issued by EMF-NET offers a lengthy list of European projects on the biological effects of power line and wireless communication electromagnetic fields. The list also includes projects on potential risks related to exposure in the working environment. The EMF-NET project is an initiative of the EC and is titled "Effects of the exposure to electromagnetic fields: from science to public health and safer workplace." This four-year project, which is to conclude in 2008, is one of the most ambitious and all-encompassing programs funded by the EC to date. It targets exposures from a wide range of nonionizing electromagnetic-energy-emitting devices, sources, and systems - including power lines, cellular mobile phones, base stations, broadcasting antennas, and household electrical appliances such as mixers and induction ovens (IH hobs) - as well as various electromagnetic equipment found in industry environments and health care facilities [ABSTRACT FROM PUBLISHER]

This paper is aimed at understanding, and visualizing, the fate of the high-energy positrons in the body as they lose energy and thermalize through collisions before annihilating. It provides information on the spatial extent of their transport from the site of emission and the potential damage that can be caused along these tracks. It has ramifications for positron emission tomography and for charged particle dosimetry in general. [ABSTRACT FROM AUTHOR]