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Radiochromic films change color upon exposures to radiation doses as a result of solid-state polymerization (SSP). Commercially available radiochromic films are primarily designed for, and have become widely used in, clinical X-ray dosimetry. However, many intriguing properties of radiochromic films are not yet fully understood. The present work aimed at developing a theoretical model at both atomic and macroscopic scales to provide a platform for future works to understand these intriguing properties. Despite the fact that radiochromic films were primarily designed for clinical X-ray dosimetry, dose-response curves for the Gafchromic EBT3 film obtained for ultraviolet (UV) radiation were employed to develop our model in order to avoid complications of ionization, non-uniform energy deposition, as well as dispersed doses caused by secondary electrons set in motion by the indirectly ionizing X-ray photons, which might introduce added uncertainties to the model and overshadow the basic SSP processes. The active layer in the EBT3 film consisted of diacetylene (DA) pentacosa-10,12-diynoate monomers, which were modelled using molecular dynamics (MD). The degrees of SSP in the atomic scale upon different UV exposures were obtained to determine the absorption coefficients of the active layer, which were then input into the finite element method (FEM). The classical steady-state Helmholtz equation was engaged to model the reflection from the active layer using the FEM technique. The multifrontal massively parallel sparse direct solver (MUMPS) was employed to solve the present numerical problem. Very good agreement between experimentally and theoretically obtained coloration in terms of net reflective optical density was achieved for different UV exposures. In particular, for UV exposures larger than ***40 J/cm², the reflected light intensity decreased at a lower rate when compared to other UV exposure values, which was explained by the densely cross-linked structure under near-complete polymerization, and thus the lower efficiency for further bond formation between DA monomer strands. [ABSTRACT FROM AUTHOR]

Ra, Th and K activity concentrations have been determined by gamma-ray spectrometry in different types of marble, granite and ceramic tiles that are commonly used for interior and exterior purposes in buildings in Riyadh, Saudi Arabia. Marble showed the lowest concentrations of the three measured radionuclides, while the highest Ra and K activities were found in granite and the highest Th concentration was found in ceramic samples. Activity measurements were used to calculate the elemental concentrations of uranium and thorium and to assess the associated radiation hazards by evaluating various radiological hazard indices, such as radium equivalent activity, external and internal hazard indices and gamma and alpha radiation indices. Moreover, the absorbed gamma dose rate in indoor air, annual effective dose equivalent and annual gonadal dose equivalent were also presented. In most cases, the calculated parameters showed levels below the permissible limits indicating the safe use of these materials for building constructions. The relative contribution of the natural radionuclides to the radiation dose in the studied materials as well as the hazard portion due to exhaled radon was also estimated. The lifetime risk assessment from exposure to gamma sources in the investigated samples showed values in the range of 10-10. [ABSTRACT FROM AUTHOR]

Monte Carlo method was used to study the characteristics of neutron interactions with cells underneath a water medium layer with varying thickness. The following results were obtained. (1) The fractions of neutron interaction with 1H, 12C, 14N and 16O nuclei in the cell layer were studied. The fraction with 1H increased with increasing medium thickness, while decreased for 12C, 14N and 16O nuclei. The bulges in the interaction fractions with 12C, 14N and 16O nuclei were explained by the resonance spikes in the interaction cross-section data. The interaction fraction decreased in the order: 1H > 16O > 12C > 14N. (2) In general, as the medium thickness increased, the number of “interacting neutrons” which exited the medium and then further interacted with the cell layer increased. (3) The area under the angular distributions for “interacting neutrons” decreased with increasing incident neutron energy. Such results would be useful for deciphering the reasons behind discrepancies among existing results in the literature. [ABSTRACT FROM AUTHOR]

Inhalation of radon (Rn) and its decay products are a major source of natural radiation exposure. It is known from recent surveys in many countries that radon and its progeny contribute significantly to total inhalation dose and it is fairly established that radon when inhaled in large quantity causes lung disorder. In recent times, numerical modelling has become the cost effective replacement of experimental methods for the prediction and visualization of indoor pollutant distribution. The aim of this study is to implement the Finite Volume Method (FVM) for studying the radon distribution indoor. The findings show that the radon concentration which is distributed in a non-homogeneous way in the room is due to the difference in the radon concentration of different sources (wall, floor and ceiling). Moreover, the radon concentration is much larger near walls, and decreases in the middle of the room because of the effect of air velocity. We notice that the simulation results of radon concentration are in agreement with the results of other experimental studies. The annual effective dose of radon in the model room has been also investigated. [ABSTRACT FROM AUTHOR]

Radiotherapy is a common cancer treatment module, where a certain amount of dose will be delivered to the targeted organ. This is achieved usually by photons generated by linear accelerator units. However, radiation scattering within the patient’s body and the surrounding environment will lead to dose dispersion to healthy tissues which are not targets of the primary radiation. Determination of the dispersed dose would be important for assessing the risk and biological consequences in different organs or tissues. In the present work, the concept of conversion coefficient (F) of the dispersed dose was developed, in which F = (Dd/Dt), where Dd was the dispersed dose in a non-targeted tissue and Dt is the absorbed dose in the targeted tissue. To quantify Dd and Dt, a comprehensive model was developed using the Monte Carlo N-Particle (MCNP) package to simulate the linear accelerator head, the human phantom, the treatment couch and the radiotherapy treatment room. The present work also demonstrated the feasibility and power of parallel computing through the use of the Message Passing Interface (MPI) version of MCNP5. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Physiology & Pharmacology is the property of Canadian Science Publishing 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.)

Naturally-occurring radioactive materials wastes in the oil and gas industry create a radioactive environment for the workers in the field. MCNP simulation conducted in this work provides a useful tool in terms of radiation safety design of the oil field, as well as validation and an important addition to in situ measurements. Furthermore, phantoms are employed to observe the dose distribution throughout the human body, demonstrating radiation effects on each individual organ. [ABSTRACT FROM AUTHOR]

The vertical downward migration of U in soils collected from south-western Punjab was studied from the depth distributions using the diffusion-convection model. The time-dependent convective rates ( ν) of U were found to be in the order of 10-10 cm year, whereas under the assumption of steady state (time-independent), values were in the order of 10-10 cm year. However, the diffusion rates ( D) were in the order of 10-10 cm year and under the steady state, values obtained to be relatively higher as 0.002-0.70 cm year. These values were within the range of reported literature values. [ABSTRACT FROM AUTHOR]

A study was conducted to dose analysis of human body organs of ORNL mathematical phantom as a personnel in radiation field of the 2.5 kJ plasma focus device. The dose calculations were performed for 10 fusion neutrons per shot (with energy of 2.45 MeV) from deuterium and deuterium fusion (D-D) using Monte Carlo MCNP code. Based on the results, assuming 2600 shots/year (10 shots/day), equivalent and effective dose obtained by operator in different distances from plasma focus device is less than the determined yearly working dose which is assumed 20 mSv/year. The calculations showed that for working in close distances to PF (distance about 50 cm) or in the PF radiation field with more than 10 shots/day, Polyethylene (with 5 % B) with 10 cm in thickness is sufficient to reduce effective dose less than 20 mSv/year. [ABSTRACT FROM AUTHOR]

Purpose: The area of southeastern Serbia, the Pčinja and South Morava River Basins, is under the influence of very strong erosion, and the aim of this study was to investigate the vertical and spatial distribution of the Cs in the eroded soils of this area. Materials and methods: Vertical soil profiles were collected with 5-cm increments from the uppermost layer down to 20, 25, 30, 40, and 50 cm of depth, depending on the thickness of the soil layers, i.e., down to the underlying parent rocks. Measurements of Cs activity concentration were performed by using the HPGe gamma-ray spectrometer ORTEC-AMETEK (34 % relative efficiency and high resolution 1.65 keV at 1.33 MeV for Co), from its gamma-ray line at 661.2 keV. Results and discussion: The mean Cs activity concentration across all 18 soil profiles (for all soil layers) was found to be 20 Bq kg. In the greatest number of soil profiles, the Cs activity concentration was generally highest in the first soil layer (0-5 cm) and decreased with soil depth, while in a few soil profiles, the peak of either the Cs activity concentration occurred in the second soil layer (5-10 cm) or the Cs activity concentration was almost equal throughout the entire soil profile. The mean Cs activity concentration in the first soil layer (0-5 cm) was found to be 61 Bq kg, and the high coefficient of variation of 92 % pointed out high spatial variability and large range of the Cs activity concentrations in the study area. Conclusions: The obtained results indicate that in the greatest number of soil profiles, Cs is present in the upper layers, with concentration decreasing with depth, as is typical in uncultivated soil. Its spatial distribution was very uneven among the surface soil layers of the investigated sites. One of the main reasons for such pattern of Cs in the study area may be soil erosion. Additional investigations which would support this hypothesis are required. [ABSTRACT FROM AUTHOR]

Copyright of Physics Essays is the property of Physics Essays Publication 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.)

Activity concentrations of K, Ra and Th were measured in five different environmental matrices and food crops collected from some elevated radiation areas of Sikiti south-west Nigeria to estimate the radiation dose incur by the population. In situ gamma dose rates were also measured at every collection point for comparison. The activity concentrations of the various radionuclides obtained for rock samples collected from mining sites were generally higher than those of other matrices except Ra that is relatively low in rocks of the study area. Radiological hazard indices were estimated to assess the harmful effects of gamma radiation to the population dwelling in the area. The activity concentrations and the estimated radiological parameters were comparable to values obtained in elevated radiation areas around the world. The mean in situ measured absorbed dose rate is 232.8 ± 49.8 nGy h, which is far greater than the worldwide mean outdoor value of 60 nGy h. The total annual effective ingestion dose obtained in this study is 339.4 µSv year, which is higher than the 290 µSv year reported as the world average value. Also, the total annual effective dose due to external and internal gamma radiation exposures in the study area is 1.83 mSv year, which is greater than the 1 mSv year recommended by ICRP for members of the public. It can therefore be concluded that the radiological risks to the general population from gamma radiation due to natural radionuclides in the area are significant. [ABSTRACT FROM AUTHOR]

Radioactivity concentrations and heavy metal content were measured in soil samples collected from the area of Kragujevac, one of the largest cities in Serbia. The specific activities of Ra, Th, K and Cs in 30 samples were measured by gamma spectrometry using an HPGe semiconductor detector. The average values ± standard deviations were 33.5 ± 8.2, 50.3 ± 10.6, 425.8 ± 75.7 and 40.2 ± 26.3 Bq kg, respectively. The activity concentrations of Ra, Th and Cs have shown normal distribution. The annual effective doses, radium equivalent activities, external hazard indexes and excess lifetime cancer risk were also estimated. A RAD7 device was used for measuring radon exhalation rates from several samples with highest content of Ra. The concentrations of As, Co, Cr, Cu, Mn, Ni, Pb and Zn were measured, as well as their EDTA extractable concentrations. Wide ranges of values were obtained, especially for Cr, Mn, Ni, Pb and Zn. The absence of normal distribution indicates anthropogenic origin of Cr, Ni, Pb and Zn. Correlations between radionuclide activities, heavy metal contents and physicochemical properties of analysed soil were determined by Spearman correlation coefficient. Strong positive correlation between Ra and Th was found. [ABSTRACT FROM AUTHOR]

Measurements of radon activity concentrations have been conducted in public kindergartens, primary, and secondary schools in Kragujevac City. This study represents the first step towards radon mapping of Central Serbia. Passive discriminative radon/thoron detectors (so called UFO) were used for monitoring. The radon calibration coefficient of 0.026 (track/cm2)/(Bq m−3 day) was calculated by exposing the UFO detectors in a Rn chamber monitored by a RAD7 device. The Rn concentration was in the range of 27-145 Bq m−3 in kindergartens and 25-86 Bq m−3 in schools. The value of the arithmetic mean was 59.6 Bq m−3 and the standard deviation was 25.6 Bq m−3. The distribution of the results was well fitted by log-normal function. No significant correlation between measured activity concentrations and periods of building constructions was found. [ABSTRACT FROM AUTHOR]

The goal of this study was focused on determination of the specific activity of 137Cs in the samples of cultivated and uncultivated soil, as well as comparison with specific countries. The samples were taken from 14 locations in the surrounding of the city of Skopje. The spectral analysis of the radionuclides of these samples was conducted by applying a γ-ray spectrometer with high purity germanium (HPGe) detector with 30% relative efficiency. The data show that the specific activities of this radionuclide vary within a range of 6,04 Bq/kg (measured in Dracevo at a depth of 15 cm) to a maximal value of 21,87 Bq/kg (measured in Radisani at a depth of 5 cm) for cultivated land. The specific activities of this radionuclide vary within a range of 5,01 Bq/kg (measured in Radisani at a depth of 10-15 cm) to a maximal value of 19,05 Bq/kg (measured in Bardovci at a depth of 0-5 cm) for non-cultivated land. On the basis of the obtained results, an expressed variability is perceived regarding the specific activities of 137Cs in the examined soil samples according to location and depth. The very research indicates that in both types of soil, the highest level of 137Cs exists at a depth of 5 cm which is in accordance with the literature data. In the examined locations there is no need of special procedures for soil decontamination, however the familiarization with the methods related to the decrease of the radiological activity can be beneficial considering the fact that the soil is a part of the link soil-food-human. [ABSTRACT FROM AUTHOR]

We demonstrate a high-throughput charged particle analysis platform, which is based on lensfree on-chip microscopy for rapid ion track analysis using allyl diglycol carbonate, i.e., CR-39 plastic polymer as the sensing medium. By adopting a wide-area opto-electronic image sensor together with a source-shifting based pixel super-resolution technique, a large CR-39 sample volume (i.e., 4 cm x 4 cm x 0.1 cm) can be imaged in less than 1 min using a compact lensfree on-chip microscope, which detects partially coherent in-line holograms of the ion tracks recorded within the CR-39 detector. After the image capture, using highly parallelized reconstruction and ion track analysis algorithms running on graphics processing units, we reconstruct and analyze the entire volume of a CR-39 detector within ~1.5 min. This significant reduction in the entire imaging and ion track analysis time not only increases our throughput but also allows us to perform time-resolved analysis of the etching process to monitor and optimize the growth of ion tracks during etching. This computational lensfree imaging platform can provide a much higher throughput and more cost-effective alternative to traditional lens-based scanning optical microscopes for ion track analysis using CR-39 and other passive high energy particle detectors. [ABSTRACT FROM AUTHOR]

The rates of radon exhalation from building materials available on the Serbian market were measured using RAD7 device. Fitting the growth curves of radon activity concentration provided the information on radon exhalation rates from the samples. The results were quite low and they ranged from 1.4 to 855 mBq m h for surface exhalation rate and from 1.3 to 11.4 mBq kg h for mass exhalation rate. The effect of moisture on radon exhalation was confirmed. For powdered samples with dimensions smaller than radon diffusion length, the mass exhalation rate is independent of sample mass and its exhalation area. [ABSTRACT FROM AUTHOR]

The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray fluences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-Kα and Kβ x-rays. The CR-39 detectors were then exposed to 1-5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those not exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula. [ABSTRACT FROM AUTHOR]

Measuring of radon and thoron progeny concentrations in air, based on air filtration, was analysed in order to assess the reliability of the method. Changes of radon and thoron progeny activities on the filter during and after air sampling were investigated. Simulation experiments were performed involving realistic measuring parameters. The sensitivity of results (radon and thoron concentrations in air) to the variations of alpha counting in three and five intervals was studied. The concentration of 218Po showed up to be the most sensitive to these changes, as was expected because of its short half-life. The well-known method for measuring of progeny concentrations based on air filtration is rather unreliable and obtaining unrealistic or incorrect results appears to be quite possible. A simple method for quick estimation of radon potential alpha energy concentration (PAEC), based on measurements of alpha activity in a saturation regime, was proposed. Thoron PAEC can be determined from the saturation activity on the filter, through beta or alpha measurements. [ABSTRACT FROM AUTHOR]

Natural radioactivity is responsible for most of the total radiation dose received by human population. Geological materials used in building industry usually become contaminated with naturally occurring radioactive materials. They are used as mixtures in building industry (kaolin, zircon, frit, feldspar) or mechanically processed and used for covering floors and walls of the rooms (granite). In this paper, activity concentrations of Ra, Th and K in 6 kaolin, 11 zircon, 18 granite, 3 marble, 6 sand, 4 perlite, 4 feldspar, 5 korund and 1 frit samples imported in Serbia were determined by gamma-ray spectrometry. Activity concentration index, dose rate and annual effective dose were calculated for each of the investigated samples. Measurement of an external gamma dose rate by using a commonly available radiation survey meter can give some indication of the need for further investigations. The absorbed dose rate and annual effective doses for workers in the ceramic industry 'Keramika Kanjiza Plus' in Serbia working with granite are determined. [ABSTRACT FROM AUTHOR]

Measurements of activity concentrations of natural radionuclides in and around Obajana cement factory, North Central Nigeria have been carried out in this study to determine the activity levels of natural radionuclides in different environmental matrices in order to assess the radiological health hazards associated with the use of these matrices by the local population. A low-background Pb-shielded gamma spectroscopic counting assembly utilizing NaI (Tl) detector was employed for the measurements. The results show that sediment samples have the highest activity concentrations of all the radionuclides relative to soil, farmland soil, and rock samples. The radium equivalent activity and indoor gamma dose rates together with the corresponding annual effective indoor doses evaluated were found to be lower than their permissible limits. It suffices to say, that contrary to age-long fear of radiation risks to the population in the vicinity of the cement factory, no excessive radiological health hazards either indoors and/or outdoors is envisaged. Therefore, the environmental matrices around the factory could be used without any restrictions. [ABSTRACT FROM AUTHOR]

Purpose: The vertical distribution of Cs-an artificial fallout radionuclide-is controlled by soil characteristics and processes that may differ among soil groups. The application of a single modelling approach to large number of soil profiles provides an original contribution to the literature and allows for comparison between these different soil groups. Materials and methods: In order to quantify Cs migration in soils, we compiled and modelled depth-distributed data documented in the literature published before 2013. The resulting database comprised ninety-nine Cs profiles sampled in 14 soil groups of the World Reference Base (WRB) classification (FAO ) under different land uses or covers and collected at various geographical locations in the Northern hemisphere between 1992 and 2007. Results and discussion: The Cs profiles were classified in seven different categories according to the shape and location of radiocaesium peak. Depth of the latter ranged between 0 and 12 cm (median of 2 cm) and maximal penetration of cesium reached from 12 to 60 cm. The Cs depth distributions in these soils were fitted using a diffusion-convection equation to allow comparison between different soil groups. Diffusion coefficients ranged from 0.02 to 4.44 cm years in soils (median of 0.64 cm year), and convection velocities varied from 0 to 0.74 cm year (median of 0.1 cm year). The model underestimated Cs concentrations by a median value of 1.9 % of the total inventory in soil samples collected below a 13-cm depth. Conclusions: Global Cs penetration velocities ranged from 0.05 to 0.76 cm year (median of 0.28 cm year) over a 25-year period. Our results showed that modelling Cs depth profile with a diffusion-convection equation allowed estimating the bioturbation and clay translocation velocity in a certain number of soil groups. This quantification is crucial as these processes partially control the development of soil surface characteristics and several soil services. [ABSTRACT FROM AUTHOR]

The track etch detector, CR-39, in common usage, is highly sensitive to recording charged particles. CR-39 polymer samples were irradiated with alpha particles at different energies (2.17 MeV and 3.95 MeV) followed by chemical etching with different times (1.50, 3.00 and 6.00 h). Tire tracks formed in CR-39 due to irradiations were visualized by using etching technique. The optical properties of the CR-39 polymer before and after the etching processes were studied with ultraviolet-visible (UV-vis) spectroscopy. The optical band gap energy was calculated for the CR-39 polymer samples. The average value of the track diameter of irradiation at 2.17 MeV and etching time 1.5 h is fairly large compared with its value at 3.95 MeV. This is due to the production of defect levels in the band gap of polymer at the 2.17 MeV. The results revealed that the CR-39 samples at 3.00 h are insensitive to the optical variations in the fundamental absorption edge. [ABSTRACT FROM AUTHOR]

A sensitive radioactive aerosols sensor has been designed and developed. Its design guidance is based on the need for a low operational cost and reliable measurements to provide daily aerosol monitoring. The exposure of diethylene-glycol bis (allylcarbonate) to radiation causes modification of its physico-chemical properties like surface roughness and reflectance. In the present study, optical sensor based on the reflectance measurement has been developed with an aim to monitor real time presence of alpha radioactive aerosols emitted from thorium nitrate hydrate. The results shows that the fabricated sensor can detect 0.0157 kBq to 0.1572 kBq of radio activity by radioactive aerosols generated from (Th(NO3)4⋅5H2O) at 0.1 ml/min flow rate. The proposed instrument will be helpful to monitor radioactive aerosols in/around a nuclear facility, building construction sites, mines, and granite polishing factories. [ABSTRACT FROM AUTHOR]

Simple Summary: An increasing number of cancer patients are treated with proton therapy. Nevertheless, there are still open questions that require preclinical studies, for example, those regarding long-term side effects or new treatment approaches. In this review, we discuss the main research topics of proton radiobiology and describe the typical challenges related to preclinical experiments in this field. We provide a summary of the different available preclinical models, and how they were applied to conduct proton-specific research in the past. This includes cell culture models of increasing complexity, animal studies, and computer simulations. In addition, we give an overview of possible endpoints and suggest models from other disciplines for adaptation to biomedical proton research. In doing so, we contribute to designing meaningful research studies in the future, which will ultimately help to improve patient treatment. The number of proton therapy centers worldwide are increasing steadily, with more than two million cancer patients treated so far. Despite this development, pending questions on proton radiobiology still call for basic and translational preclinical research. Open issues are the on-going discussion on an energy-dependent varying proton RBE (relative biological effectiveness), a better characterization of normal tissue side effects and combination treatments with drugs originally developed for photon therapy. At the same time, novel possibilities arise, such as radioimmunotherapy, and new proton therapy schemata, such as FLASH irradiation and proton mini-beams. The study of those aspects demands for radiobiological models at different stages along the translational chain, allowing the investigation of mechanisms from the molecular level to whole organisms. Focusing on the challenges and specifics of proton research, this review summarizes the different available models, ranging from in vitro systems to animal studies of increasing complexity as well as complementing in silico approaches. [ABSTRACT FROM AUTHOR]

Radiocaesium is a pollutant with a high risk for the environment, agricultural production, and human health. It is mobile in ecosystems and can be taken up by plants via potassium transporters. In this study, we focused on the role of potassium transporter AtKUP7 of the KT/HAK/KUP family in Cs+ and K+ uptake by plants and in plant tolerance to caesium toxicity. We detected that Arabidopsiskup7 mutant accumulates significantly lower amounts of 134Cs in the root (86%) and in the shoot (69%) compared to the wild-type. On the other hand ability of the mutant to grow on media with toxic (100 and 200 µM) concentrations of Cs+ was not changed; moreover its growth was not impaired on low K+. We further investigated another mutant line in AtKUP7 and found that the growth phenotype of the kup7 mutants in K+ deficient conditions is much milder than previously published. Also, their accumulation of K+ in shoots is hindered only by severe potassium shortage. [ABSTRACT FROM AUTHOR]

This article presents a new perspective on the development of inorganic scintillator-based fiber dosimeters (IOSFDs) for medical radiotherapy dosimetry (RTD) focusing on real-time in vivo dosimetry. The scintillator-based optical fiber dosimeters (SFD) are compact, free of electromagnetic interference, radiation-resistant, and robust. They have shown great potential for real-time in vivo RTD. Compared with organic scintillators (OSs), inorganic scintillators (IOSs) have larger X-ray absorption and higher light output. Variable IOSs with maximum emission peaks in the red part of the spectrum offer convenient stem effect removal. This article outlines the main advantages and disadvantages of utilizing IOSs for SFD fabrication. IOSFDs with different configurations are presented, and their use for dosimetry in X-ray RT, brachytherapy (BT), proton therapy (PT), and boron neutron capture therapy (BNCT) is reviewed. Challenges including the percentage depth dose (PDD) deviation from the standard ion chamber (IC) measurement, the angular dependence, and the Cherenkov effect are discussed in detail; methods to overcome these problems are also presented. [ABSTRACT FROM AUTHOR]

Despite extensive efforts in studying radioactive aerosols, including the transmission of radionuclides in different chemical matrices throughout the body, the internal organ-specific radiation dose due to inhaled radioactive aerosols has largely relied on experimental deposition data and simplified human phantoms. Computational fluid-particle dynamics (CFPD) has proven to be a reliable tool in characterizing aerosol transport in the upper airways, while Monte Carlo based radiation codes allow accurate simulation of radiation transport. The objective of this study is to numerically assess the radiation dosimetry due to particles decaying in the respiratory tract from environmental radioactive exposures by coupling CFPD with Monte Carlo N-Particle code, version 6 (MCNP6). A physiologically realistic mouth-lung model extending to the bifurcation generation G9 was used to simulate airflow and particle transport within the respiratory tract. Polydisperse aerosols with different distributions were considered, and deposition distribution of the inhaled aerosols on the internal airway walls was quantified. The deposition mapping of radioactive aerosols was then registered to the respiratory tract of an image-based whole-body adult male model (VIP-Man) to simulate radiation transport and energy deposition. Computer codes were developed for geometry visualization, spatial normalization, and source card definition in MCNP6. Spatial distributions of internal radiation dosimetry were compared for different radionuclides (131I, 134,137Cs, 90Sr-90Y, 103Ru and 239,240Pu) in terms of the radiation fluence, energy deposition density, and dose per decay. [ABSTRACT FROM AUTHOR]

Highlights of the articles in this issue are given in the PDF file. [ABSTRACT FROM AUTHOR]

A calibration method was proposed in the present work to determine the medium-thickness-dependent proton doses absorbed in cellular components (i.e., cellular cytoplasm and nucleus) in radiobiological experiments. Consideration of the dependency on medium thickness was crucial as the linear energy transfer (LET) of protons could rise to a sharp peak (known as the Bragg peak) towards the end of their ranges. Relationships between the calibration coefficient R vs medium-layer thickness were obtained for incident proton energies of 10, 15, 20, 25, 30 and 35 MeV, and for various medium thicknesses up to 5000 μm, where R was defined as the ratio DA/DE, DA was the absorbed proton dose in cellular components, and DE was the absorbed proton dose in a separate radiation detector. In the present work, DA and DE were determined using the MCNPX (Monte Carlo N-Particle eXtended) code version 2.4.0. For lower incident proton energies (i.e., 10, 15 and 20 MeV), formation of Bragg-peak-like features were noticed in their R-vs-medium-layer-thickness relationships, and large R values of >7 and >6 were obtained for cytoplasm and nucleus of cells, respectively, which highlighted the importance of careful consideration of the medium thickness in radiobiological experiments. [ABSTRACT FROM AUTHOR]

In this paper, we present a model of the gamma irradiation room at the National Institute of Nuclear Research (ININ is its acronym in Spanish) in Mexico to improve the use of physics in dosimetry for human protection. We deal with air-filled ionization chambers and scientific computing made in house and framed in both the GEANT4 scheme and our analytical approach to characterize the irradiation room. This room is the only secondary dosimetry facility in Mexico. Our aim is to optimize its experimental designs, facilities, and industrial applications of physical radiation. The computational results provided by our model are supported by all the known experimental data regarding the performance of the ININ gamma irradiation room and allow us to predict the values of the main variables related to this fully enclosed space to within an acceptable margin of error. [ABSTRACT FROM AUTHOR]