Total Amount Of Radiation Research Articles

Modelling and Optimization of a Concentrating PV-Mirror System

The paper presents results on a novel low concentration system for photovoltaic/ hybrid module, its geometric modelling and the optimal working parameters. The low concentration system is build up of a PV module and two mirrors, one on the left side and symmetrically on the right side along the length of the PV module. Our objective is to maximize the received direct radiation of the PV or hybrid module, maintaining an overall geometric size of the system as small as possible with a minimum number of the tracking steps. Two cases were considered: the first case when the reflected solar radiation from each mirror sweeps the whole surface of the PV module increasing by almost 2x the amount of radiation that sweeps the PV-surface; the second case when the reflected light from each mirror partially sweeps the PV-module surface, building together one cover of light on the plane and increasing the amount of radiation that falls on the module surface around 1x. Although the total amount of radiation that falls on the photovoltaic/hybrid module surface in the second case is far less than in the first situation, the overall size of the system is strongly reduced.

Gold-Enhanced Brachytherapy by a Nanoparticle-Releasing Hydrogel and 3D-Printed Subcutaneous Radioactive Implant Approach.

Brachytherapy (BT) is a widely used clinical procedure for localized cervical cancer treatment. In addition, gold nanoparticles (AuNPs) have been demonstrated as powerful radiosensitizers in BT procedures. Prior to irradiation by a BT device, their delivery to tumors can enhance the radiation effect by generating low-energy photons and electrons, leading to reactive oxygen species (ROS) production, lethal to cells. No efficient delivery system has been proposed until now for AuNP topical delivery to localized cervical cancer in the context of BT. This article reports an original approach developed to accelerate the preclinical studies of AuNP-enhanced BT procedures. First, an AuNP-containing hydrogel (Pluronic F127, alginate) is developed and tested in mice for degradation, AuNP release, and biocompatibility. Then, custom-made 3D-printed radioactive BT inserts covered with a AuNP-containing hydrogel cushion are designed and administered by surgery in mice (HeLa xenografts), which allows for measuring AuNP penetration in tumors (≈100µm), co-registered with the presence of ROS produced through the interactions of radiation and AuNPs. Biocompatible AuNPs-releasing hydrogels could be usedin the treatment of cervical cancer prior to BT, with impact on the total amount of radiation needed per BT treatment, which will result in benefits to the preservation of healthy tissues surrounding cancer.

ВЛИЯНИЕ КЛИМАТИЧЕСКОГО ФАКТОРА НА ОСВОЕНИЕ ГОРНЫХ ГЕОСИСТЕМ И ВОЗНИКАЮЩИЕ ЭКОЛОГИЧЕСКИЕ ПРОБЛЕМЫ

Being one of the main components of the ecosystem, the climate plays an important role in the development of various economic areas of the territory, including the resettlement of the population. Climatic factors, such as temperature, precipitation, wind, etc., have a special impact on the development of agriculture - agrocenoses, as well as tourism. The article studies the influence of climatic features of the Nakhichevan Autonomous Republic on the development of agricultural areas of the territory. At the same time, special attention was paid to temperatures above 50 and 100C, the humidity coefficient, the continuity of sunny days, and the total amount of radiation. It should be noted that each of the climatic factors was analyzed separately, the degree of suitability and development of the study area for the development of agrocenoses was studied, and the environmental problems that arose and may arise during this period were studied.

Оценка методов расчета значений суммарной солнечной радиации для различных интервалов времени

The article presents the results of evaluation of a number of methods for calculating total, scattered and direct radiation. The methods were tested on actinometric data of eight stations of the former USSR, located in different climatic and latitudinal zones, in order to clarify the spatial boundaries of their application and the time interval for which it is possible to carry out calculations with an error of not more than 10 %. It is established that the accuracy of calculations is influenced by the location of the station in relation to the seas and lakes. In addition, a number of methods do not take into account the tier and shape of the cloud, so at the same amount of cloud observed different amounts of total radiation, which in turn leads to errors in the calculation of the amounts of radiation. For stations with high atmospheric transparency and low air humidity, the calculation methods provide understated data compared to full-scale ones. For stations with high dust content of the surface layer of the atmosphere, the calculated data are overstated. For marine and lake stations, overestimation of the calculated data is caused by increased humidity throughout the year and as a result, even with a small cloud cover, incoming solar radiation is significantly weakened by water vapor. The considered calculation methods can be used to calculate monthly amounts of total radiation with an accuracy of 10-12 %. Calculation for shorter time intervals leads to an increase in calculation errors. Using the method of calculating the total radiation components gives an error in the calculation of monthly amounts from 10 to 30 %, depending on the latitude. Performing calculations using this method for time intervals less than a month leads to a sharp increase in the size of errors.

A New Pathway for Incorporating the Impact of Solar Flares and Other Space Activity into Climate Modelling

A recent development in climate research is the recognition that space activity such as solar flares, gamma ray bursts, supernovas etc. can have a significant impact on the Earth. The existing methods of modelling space activity do not model these phenomena explicitly. Instead, their effect on ionization rates is formulated and then built into existing climate models. In this paper, based on the authors’ earlier work, several analytical approaches for modelling a solar flare hitting the Earth are presented. These methods can also be used for modelling gamma-ray bursts or cosmic rays striking our planet. In addition, a method of calculating the total amount of radiation received during a solar flare is proposed. The future use of the proposed modelling approaches within comprehensive global climate models allows for explicit modelling of space activity and provides a new pathway for studying the possible effects of this activity on the Earth.

Studying the impact of biomass burning aerosol radiative and climate effects on the Amazon rainforest productivity with an Earth system model

Abstract. Diffuse light conditions can increase the efficiency of photosynthesis and carbon uptake by vegetation canopies. The diffuse fraction of photosynthetically active radiation (PAR) can be affected by either a change in the atmospheric aerosol burden and/or a change in cloudiness. During the dry season, a hotspot of biomass burning on the edges of the Amazon rainforest emits a complex mixture of aerosols and their precursors and climate-active trace gases (e.g. CO2, CH4, NOx). This creates potential for significant interactions between chemistry, aerosol, cloud, radiation and the biosphere across the Amazon region. The combined effects of biomass burning on the terrestrial carbon cycle for the present day are potentially large, yet poorly quantified. Here, we quantify such effects using the Met Office Hadley Centre Earth system model HadGEM2-ES, which provides a fully coupled framework with interactive aerosol, radiative transfer, dynamic vegetation, atmospheric chemistry and biogenic volatile organic compound emission components. Results show that for present day, defined as year 2000 climate, the overall net impact of biomass burning aerosols is to increase net primary productivity (NPP) by +80 to +105 TgC yr−1, or 1.9 % to 2.7 %, over the central Amazon Basin on annual mean. For the first time we show that this enhancement is the net result of multiple competing effects: an increase in diffuse light which stimulates photosynthetic activity in the shaded part of the canopy (+65 to +110 TgC yr−1), a reduction in the total amount of radiation (−52 to −105 TgC yr−1) which reduces photosynthesis and feedback from climate adjustments in response to the aerosol forcing which increases the efficiency of biochemical processes (+67 to +100 TgC yr−1). These results illustrate that despite a modest direct aerosol effect (the sum of the first two counteracting mechanisms), the overall net impact of biomass burning aerosols on vegetation is sizeable when indirect climate feedbacks are considered. We demonstrate that capturing the net impact of aerosols on vegetation should be assessed considering the system-wide behaviour.

Image Optimization and reduction of radiation dose in CT of the paranasal sinuses

Introduction: Since demand for computed tomography (CT) examinations is growing, patients are exposed more frequently to ionizing radiation. To reduce the dose delivered to patients in each scan, CT technologists can change the image acquisition parameters. However, this reduces image quality. Present study aimed to optimize and reduce radiation dose in a CT of the paranasal sinuses while minimizing deterioration of image quality Materials and Methods: We divided the patients into two study groups: Group A was scanned axially and coronally using default parameters, while Group B was scanned axially and coronally using new parameters. The patients’ organ doses were estimated using the ImpactDose calculator. The tube voltage, tube current, pitch, rotation time, and other parameters were then reduced and optimized. After reconstruction and analysis, all of the images were of good diagnostic quality in both groups Results: Using the new parameters, good agreement was found between the direct and reconstructed images. The CT parameters were reduced by the following proportions: kVp— 16.6%, mA—75%, rotation time—20%, and mAs—80%. However, these reductions did not obscure any anatomical landmarks. These parameters reduced the CTDIw, CTDIvol and DLP by 88.2%, 91.3%, and 91.3% respectively. Conclusion: In conclusion, the results suggest that the use of a Bone algorithm reduces the total amount of radiation used during CT of the sinuses. We recommend using these parameters in children, in the evaluation of facial trauma, and in emergency CT of the paranasal sinuses

A safety radiation marker in the cardiac catheterization lab

Objective Nowadays, in order to deal with cardiovascular disease, coronary angiography (CRA) is the best tool and gold standard for diagnosis and assessment. CRA inevitably exposes both patient and operator to radiation. The purpose of this study was to calculate the radiation exposure in association with the radiation absorbed by interventional cardiologists, in order to estimate a safety radiation marker in the catheterization laboratory.Methods and results In 794 successive patients undergoing CRA and in three interventional cardiologists the following parameters were examined: radioscopy duration, radiation exposure during fluoroscopy, total radiation exposure and the number of stents per procedure. Every interventional cardiologist was exposed to 562,936 μGym2 of total radiation during CRA procedures, to 833,371 μGym2 during elective CRA + percutaneous coronary intervention (PCI) procedures and to 328,250 μGym2 during primary CRA + PCI. Hence, the total amount of radiation that every angiographer was exposed to amounted to 1,724,557.5 μGym2 (median values). During the same period, the average radiation that every angiographer absorbed was 15,253 while the average dose of radiation absorbed during one procedure was 0.06 mSv for each operator. Therefore, the ratio between radiation exposure and the radiation finally absorbed by every operator was 113:1 μGym2/mSv.Conclusions The present study, indicating the ratio above, offers a safety marker in order to realistically estimate the dose absorbed by interventional cardiologists, suggesting a specified number of permitted procedures and an effective level of radiation use protection tools.

CT Radiation Exposure: An Overview

Radiation used in CT examinations needs to be selected on image quality criteria, and also take into account the patient’s exposure. X-ray beam quality is controlled by the X-ray tube voltage (kV), and affects the X-ray beam penetration through a given patient as well as the contrast in the resultant image. CT radiation output can be characterized by the volume CTDI (CTDIvol), is controlled by tube output and CT pitch, and determines the random image noise (mottle). The total amount of radiation used to perform an examination is the dose length product (DLP), which is obtained by multiplying CTDIvol with the corresponding scan length, and is related to the corresponding patient radiation exposure. Optimal choices for CT X-ray beam characteristics (i.e., kV, CTDIvol, and DLP) need to take into account patient physical characteristics as well as the diagnostic imaging task at hand. Because CTDI metrics only describe the radiation incident on the patient, patient organ doses need to be obtained using conversion factors that account for patient size and examination scan length. Organ doses can be converted into organ risks, which can be summed to estimate the patient carcinogenic radiation risks. A 20-year-old adult weighing 75 kg, undergoing an abdominal pelvic CT examination [CTDIvol(L) 15 mGy & DLP 700 mGy-cm], has an estimated cancer induction risk of about 0.1 %. Practitioners need to understand radiation risks to be able to identify indicated examinations, where there is expected to be a net patient benefit, and to comply with the ALARA principle where unnecessary radiation is eliminated.

320 Evaluation of a novel fascial dilator modified with scale marker in PCNL for reduction of x-ray exposure: A randomized clinical study

0,8 mm); mean fluoroscopy time during URS was 116 seconds (s) (group 1), 172 s (group 2), 78 s (group 3), 83 s (group 4), observing less time of radiation exposure (p 0,05) for distal (pelvic and prevesical) than proximal (pielo-ureteral and lumbar) stones. This result was confirmed after correction for stone size. In addition, the absorbed dose was significantly lower (p 0,05) in groups 3 and 4 [mean for groups 1-4 expressed in milliGray (mGy): 1) 8,915; 2) 9,451; 3) 4,878; 4) 4,744]. 56 patients (88%) were evaluated 2 months after treatment with KUB and abdominal US, 8 patients (12%) required a CT scan to achieve the diagnosis. Mean measured exposure radiation was: 19mSv (group 1), 21msV (group 2), 15mSv (group 3), 15 mSv (group 4). CONCLUSIONS: The total radiation received by the studied population was lower than 50 mSv, the recommended dose limit in a year for workers according to International Commission on Radiological Protection. This is the first report concerning the measurement of total amount of radiation a patient submitted to URS for ureteral stone receives in his clinical fate. The use of fluoroscopy during endourological procedures increases patient’s radiation exposure and adds to all radiological diagnostic examinations. It’s critical that endourologist is sensitised to this problem in order to minimize the employ of ionising radiation during endourological treatment.

Effect of Elevated Carbon Dioxide Concentration on Carbon Assimilation under Fluctuating Light

Natural fluctuations in light intensity may significantly affect the amount of CO assimilated by plants and ecosystems. Little is known, however, about the interactive effect of dynamic light conditions and atmospheric CO concentrations. The hypothesis that elevated CO concentration (EC; 700 μmol CO mol) increases photosynthetic efficiency in dynamic light environments as compared to ambient CO concentration (AC; 385 μmol CO mol) was tested. Sun leaves of European beech ( L.) and current-year shoots of Norway spruce [ (L). Karst.] were exposed to five dynamic light regimes (LRs) occurring within forest canopies due to variable cloud cover or self-shading of leaves and to a steady-state LR. The LRs differed in the time course of incident irradiance, whereas the overall duration (600 s) and total amount of radiation (35.88 mmol photons m) were the same in all LRs. The EC treatment enhanced the amount of CO assimilated under all LRs tested. While the stimulation was only 37 to 50% in beech, it was 52 to 85% in spruce. The hypothesis that photosynthetic efficiency is stimulated by EC was confirmed in LRs when the leaves were pre-exposed to low light intensity and photosynthetic induction was required. By contrast, only a minor effect of EC treatment was found on the rate of induction loss and postillumination CO fixation in both species studied.

Instantaneous and potential radiation effect on underplanted European beech below Norway spruce canopy

In even-aged, 120-year-old Norway spruce stands with underplanted beech (in 1995) four permanent research plots were established, each 100 × 100 m in size. Twelve subplots were selected on each plot along a light gradient from complete canopy closure to open light conditions. On each plot, photon flux density (PFD) was measured continuously, and during same time interval (August 2008, 2009), color digital hemispherical photographs were taken. Cumulative PFD values for measuring points were compared with potential PFD radiation obtained from hemispherical photograph analysis for different angle of hemisphere and different parameters from hemispherical image analysis (gap fraction, total openness and direct, indirect and total amount of radiation). Cumulative and average daily values for the plots were compared; 120° hemispherical photograph angle, gap fraction and total openness were the variables that explained the largest proportion of variance in light transmittance. Determination coefficients between direct and total light component were highest for the total potential radiation and lowest for the diffuse light component. Comparison between potential and instantaneous light measurements for radial, height increment and SLA of young beech showed that instantaneous radiation measurements explained height increment best; 120° of hemisphere proved to be the best explaining angle.

The in vivo Pig‐a gene mutation assay is useful for evaluating the genotoxicity of ionizing radiation in mice

The in vivo Pig-a mutation assay has been adapted for measuring mutation in rats, mice, monkeys, and humans. To date, the assay has been used mainly to assess the mutagenicity of chemicals that are known to be powerful point mutagens. The assay has not been used to measure the biological effects associated with ionizing radiation. In this study, we modified the Pig-a gene mutation assay (Kimoto et al. [2011b]: Mutat Res 723:36-42) and used 3-color staining with fluorescently labeled anti-CD24, anti-TER-119, and anti-CD71 to detect the Pig-a mutant frequencies in total red blood cells (RBCs) and in reticulocytes (RETs) from X-irradiated mice. Single exposures to X-irradiation resulted in dose- and time-dependent increases in Pig-a mutant frequencies, and these subsequently declined over time returning to background frequencies. The same total amount of radiation, delivered either as a single dose or as four repeat doses at weekly intervals, increased Pig-a mutant frequencies to comparable levels, reaching maxima 2-3 weeks after the single dose or 2-3 weeks after the last of the repeat doses. These increased frequencies subsequently returned to background levels. Our results indicated that the 3-color Pig-a assay was useful for evaluating the in vivo genotoxicity of radiation.

Intraoperative Radiation Therapy

Radiation therapy has been used to treat cancers for over one hundred years. Over the last century our understanding of the biology of radiation exposure as well as our ability to safely deliver extraordinarily high doses of radiation to specific targets has led to its routine use in both curative and palliative settings for most solid tumors. External radiation beam techniques invariably involve irradiating normal tissues that are located between the radiation source and the intended target. High-energy linear accelerators have greatly reduced skin and subcutaneous radiation-induced injury; however, radiation tolerances of organs adjacent to the target do frequently limit the total amount of radiation that can be used. Intraoperative radiation therapy (IORT) can be delivered in a number of ways, with the ultimate intent of minimizing normal tissue exposure to potentially harmful doses of radiation. Multiple IORT delivery modalities are now available, all of which present potential advantages and disadvantages over other methods of treatment. The specific techniques, radiobiologic considerations, and clinical uses of IORT will be described.

OXIDATION OF ASCORBIC ACID AS AN INDICATOR OF PHOTOOXIDATIVE STRESS IN THE EYE

When whole retinal pigmented epithelium (RPE) cells isolated from bovine eyes are incubated with 14C-labeled ascorbic acid and exposed to a visible laser, the ascorbic acid is oxidized to dehydro-L-ascorbic acid (DHA). The amount of ascorbic acid which is oxidized is proportional to the radiant exposure of the sample (i.e. the total amount of radiation per unit area delivered over the exposure time). Blue light is more effective than red light in driving the reaction. The amount of label appearing in the DHA fraction is increased if unlabeled DHA is present in the reaction mixture, indicating that some redox cycling of ascorbate is occurring in the RPE cells. The ascorbic acid oxidizing activity does not depend on intact cells, is not inactivated by heating the cells to 80 degrees C, and appears to reside mainly in the subcellular fraction which contains melanin pigment granules. The ascorbic acid oxidation may be caused by free radicals formed when melanin is illuminated with light. This reaction appears to be a useful method for quantifying the production of free radicals during photooxidative stress.

Survey of radiographic requirements and techniques

A survey of dental schools revealed little standardization of student requirements for dental radiography in the United States. Preclinical laboratories for intraoral radiography were given by 46 schools (87 percent), but such laboratories for panoramic radiography were given by only 11 (21 percent). The majority of schools had requirements for clinical intraoral radiography based upon either clock hours or numbers of full mouth radiographic surveys. However, only 40 percent had clinical requirements for extra-oral techniques (including panoramic dental radiographs). For intraoral radiography, most emphasis was placed on the paralleling technique. There was a high degree of variability as to what constituted a full radiographic survey, and this has implications concerning the total amount of radiation to which a patient may be exposed.

The Distribution of Solar Radiation within a Deciduous Forest

Solar radiation was measured within and above an east Tennessee deciduous forest over a 2—yr period. Diurnal patterns of within—forest radiation follow the temporal variation in incident radiation but become more irregular with depth in the forest because of the highly variable penetration of beam radiation in space and in time. Seasonally, radiation in the forest increases substantially from winter to its annual maximum in early spring as solar elevations increase. Although solar elevations continue to rise each day until the summer solstice, amounts of total radiation and its beam component drop sharply in the forest with the advent of leaf expansion. Diffuse radiation in the forest continues to increase slowly following the onset of leaf expansion but reverses as the forest approaches a fully leafed state. Following the summer solstice, forest structure remains essentially static until abscission while solar elevations decrease. In summer and early autumn, total radiation and both its beam and diffuse components decrease slowly in the forest to their annual minimum in autumn. With leaf abscission and subsequent fall, radiation increases slightly in the forest but soon declines again as solar elevations approach their annual minimum of the winter solstice.

Interacting matter and radiation in homogeneous isotropic world models

Transitions between two or more fluids may result in changes of the total amount of radiation in the universe without violating overall energy conservation. Special rate equations for such processes are discussed, for which the radius of the universe as a function of time can be found by numerical integration of a single differential equation, and the radiation density can then be easily obtained, although it must be verified as positive for all times. The integrations are carried out and reported here for the simplest rate equation for two fluids for various values of the initial mass of one fluid, the transition rate, and the cosmological constant.

A method for computing the transfer of solar radiation through clouds of hexagonal ice crystals

The angular patterns that result from the scattering of solar radiation by hexagonal ice prisms were computed under the assumption that the sizes of the prisms were many times the wavelengths of the incident radiation. Using the results of geometric ray optics, a sufficiently large number of equally spaced, parallel rays were mathematically traced through the prisms (including internal reflections) in order to determine the contribution to the scattering pattern that was due to refraction and reflection. The contribution due to forward diffraction was approximated by the Kirchhoff formula. Results for a distribution of prisms in random orientation show the expected large diffraction peak in the intensity in the forward direction as well as a prominent relative maximum at an angle corresponding to the well-known halo phenomenon occasionally seen around the sun or moon. In comparison, the scattering pattern for a sphere whose size was such as to scatter out of an incident beam the same total amount of radiation as scattered out by the prisms, is also shown. The major difference in the two patterns is the absence of the halo in the case of the sphere. It can be readily shown that the energy of the radiation scattered in the angular region of the halo is comparable in magnitude to that in the forward peak, thereby showing the importance of the halo.

Persistent effects of seedling treatment on growth of sugar beet in pots

SUMMARYFurther evidence is provided that the environment of sugar‐beet seedlings, or growth substances applied to seedlings, continues to influence growth when the plants are later in other environments.Sugar‐beet seeds were germinated at 20 °C in 8, 16 or 24 h photoperiods of constant light intensity, i.e. with different amounts of total radiation. When the seedlings had two leaves (15–18 days old) they were transferred to large pots in the glasshouse. Some seedlings were treated with (2‐chloroethyltrimethylammonium chloride) either sprayed on the leaves or applied to the soil, at different times.The treatments affected areas of individual leaves throughout the growing period; plants raised in 24 h photoperiod had the largest leaves, and those in 8 h photoperiod the smallest. Consequently, 24 h plants had most dry matter and 8 h plants least. Plants given most radiation produced leaves fastest and CCC applied early increased the rate, but as the leaves were smaller, except late in 1967, and died sooner, the leaf area duration was less and so yields were less. CCC applied later did not affect leaf production. There was no interaction between amount of radiation and CCC treatment.Twenty‐four hour plants had the greatest net assimilation rate (E) early. CCC decreased E early, but increased it later and more when sprayed on the leaves than when applied to the soil.Some factor, possibly pot size, eventually restricted growth and probably diminished the effect of the treatments applied to the seedlings.