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Radiation Protection Dosimetry

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https://www.readbyqxmd.com/read/30544253/a-comparative-study-of-epr-and-tl-signals-in-gorilla%C3%A2-glass
#1
S W S McKeever, S Sholom, J R Chandler
Electron Paramagnetic Resonance (EPR) and Thermoluminescence (TL) signals have been studied in samples of Gorilla® Glass (GG) from different smartphones as well as some online stores and vendors. Background, radiation-induced and ultraviolet-induced signals were compared between the samples. Significant variability of both EPR and TL signals (in shape and intensity) was observed between samples from different screens as well as over the surface of the same screen, from the same phone. Both the EPR and TL background signals appear to be due to UV exposure during phone manufacture; some phones have higher EPR and TL signals around the edge of the screen, indicating more UV exposure at the edge than in the center...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544250/visualization-of-the-dna-repair-process-in-mammalian-cells-transfected-with-egfp-expressing-plasmid-dna-after-exposure-to-x-rays-in-vitro
#2
Hiroki Nakaue, Yui Obata, Kiichi Kaminaga, Nobuyoshi Akimitsu, Akinari Yokoya
To investigate the repair process of DNA damage induced by ionizing radiation in isolation from various types of cytoplasmic damage, we transfected X-irradiated enhanced green fluorescent protein (EGFP)-expressing plasmid DNA into non-irradiated mammalian cells using lipofectamine. The repair kinetics of the irradiated plasmids in the cells were visualized under microscopy as the EGFP fluorescence emitted by transfected cells. Using an agarose gel electrophoresis method, the yields of single- and double-strand breaks of the plasmids were also quantified...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544246/assessment-of-the-absorbed-doses-in-the-organs-in-case-of-radiation-emergency-with-the-sealed-gamma-sources
#3
V Golikov
The majority of the radiation accidents with early acute clinical effects were associated with the orphan sources used in industrial and medical facilities. These accidents involved members of general public, who were entirely unaware of the exposure to the radiation. In such situations, the exposure commonly occurs when the source is in contact with a body of a victim, primarily located in pockets of clothing or in hands. In this research, the average absorbed doses in internal organs, skin and tissues close to the source were assessed using the phantom modeling of contact human exposure by the sealed 192Ir, 137Cs and 60Co gamma sources...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544225/microdosimetry-of-clinical-ion-beams-converting-spectra-from-diamond-slab-to-water-of-different-shapes
#4
Giulio Magrin, Claudio Verona, Gianluca Verona-Rinati, Markus Stock
Microdosemeters are frequently used today to specify the radiation quality in the framework of ion-beam therapy. The heterogeneity of the detector shapes and the materials limits the possibility of comparing directly spectra and mean lineal energies. A method was recently studied to convert the spectra obtained with unidirectional ion beams in slab detectors to those obtained with detectors of different in shape and material. The method is based on the observation that the lineal-energy spectra of slab detector, in a restricted energy interval, approximate the Linear Energy Transfer distributions at corresponding material and particle type and energies...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544217/a-model-to-predict-238u-in-aquifer-rock-based-on-222rn-and-226ra-measurement-in-groundwater-samples-a-case-study-at-south-bengaluru-city-karnataka-india
#5
C G Poojitha, B K Sahoo, K E Ganesh, T S Pranesha, B K Sapra
Naturally occurring 222Rn and 226Ra concentrations were investigated in groundwater samples collected from different parts of South Bengaluru city using Smart RnDuo monitor developed indigenously by Bhabha Atomic Research Centre (BARC), India. The study area has been divided into two zones on the basis of external gamma radiation dose rates as zone A (100-200 nSv/h) and zone B (above 200 nSv/h). Radon concentration in groundwater for various sites, both supported (contribution from dissolved 226Ra in water) and unsupported (contribution from aquifer rock), was estimated...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544200/mitochondrial-membrane-potential-morphology-and-atp-production-in-mammalian-cells-exposed-to-x-rays
#6
R Hamada, K Kaminaga, K Suzuki, A Yokoya
This study aimed to reveal the effect of X-irradiation on mitochondrial function in terms of mitochondrial membrane potential (ΔΨm) and ATP productivity. At the cellular level, ΔΨm was quantified using JC-1, a mitochondrial probe that emits red or green fluorescence at high or low ΔΨm sites, respectively. The fluorescence area was quantified for both colors together relative to the whole-cell area of the same cell. The fluorescence areas versus whole-cell areas varied widely among the irradiated cells depending on the X-ray doses received (6 and 10 Gy) and incubation time, although the relative red area to total mitochondrial area was rather constant...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544197/assessing-the-contribution-of-cross-sections-to-the-uncertainty-of-monte-carlo-calculations-in-micro-and-nanodosimetry
#7
C Villagrasa, M-C Bordage, M Bueno, M Bug, S Chiriotti, E Gargioni, B Heide, H Nettelbeck, A Parisi, H Rabus
Within EURADOS Working Group 6 'Computational Dosimetry', the micro and nanodosimetry task group 6.2 has recently conducted a Monte Carlo (MC) exercise open to participants around the world. The aim of this exercise is to quantify the contribution to the uncertainty of micro and nanodosimetric simulation results arising from the use of different electron-impact cross-sections, and hence physical models, employed by different MC codes (GEANT4-DNA, PENELOPE, MCNP6, FLUKA, NASIC and PHITS). Comparison of the participants' simulation results for both micro and nanodosimetric quantities using different MC codes was the first step of the exercise...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544172/radiation-exposure-from-natural-radionuclides-in-building-materials
#8
M J Madruga, C Miró, M Reis, L Silva
Building materials from Iberian Peninsula (Portugal and Spain) were collected and analysed for 226Ra, 232Th and 40K using HPGe gamma-ray spectrometers. The results show that the highest mean value of 226Ra and 232Th activities are 2168 and 390 Bq kg-1, respectively, measured in zircon. For 40K, this value is 1290 Bq kg-1, measured in granite. The mean concentrations of the three radionuclides in the different building materials, excluding the zircon and the industrial by-products (ashes, gypsum and phosphogypsum), are 62, 31 and 519 Bq kg-1 for 226Ra, 232Th and 40K, respectively...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30544171/comparison-of-organ-based-tube-current-modulation-and-bismuth-shielding-in-chest-ct-effect-on-the-image-quality-and-the-patient-dose
#9
Antti Kotiaho, Anna-Leena Manninen, Juha Nikkinen, Miika Tapio Nieminen
The aim of the study was to compare the absorbed doses and image quality of organ-based tube current modulation (OBTCM) and bismuth shielding of breasts and thyroid against regular tube current modulation in chest CT scan. An anthropomorphic phantom and MOSFET dosemeters were used to evaluate absorbed doses. Image quality was assessed from HU and noise. Relative to the reference scan, the average absorbed dose reduction with OBTCM was 5.2% and with bismuth shields 24.2%. Difference in HU values compared to the reference varied between -4...
December 13, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535421/computational-modeling-of-low-dose-hyper-radiosensitivity-and-induced-radioresistance-applying-the-principle-of-minimum-mutation-load
#10
Balázs G Madas, Emese J Drozsdik
Low dose hyper-radiosensitivity (HRS) and induced radioresistance (IRR) can be observed in the dose dependence of survival of many different cell lines. While surviving fraction decreases exponentially in a large-scale view, a local minimum can be found at around 0.5 Gy. Although, there is evidence that the regulation of apoptosis and DNA repair are involved in HRS and IRR, the fundamental causes of the phenomena remain unclear. The objective of the present study is to test whether the principle of minimum mutation load can provide an explanation for both low dose HRS and IRR...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535407/characterization-of-a-small-fov-portable-gc-mediprobe
#11
Acampa Wanda, Capussela Tiziana, Cuocolo Alberto, Di Lillo Francesca, Punzo Giorgio, Quarto Maria, Roberti Giuseppe, Russo Paolo, Serra Marcello
In this work, we evaluated the performance of the prototype SFOV MediPROBE developed at the University of Naples Federico II through the protocol proposed by (Bhatia B.S., Bugby S.L., Lees J.E., Perkins A.C. A scheme for assessing the performance characteristics of a small field of-view gamma cameras. Physica. Medica., 31 (1), pp. 98-103. (2015) doi: 10.1016/j.ejmp.2014.08.004). We extensively investigated a new device configuration where the pinhole collimator was placed outside the housing of the probe, in order to increase the system spatial resolution, and the pixel size was doubled, in order to reduce the charge sharing effect...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535406/study-for-a-passive-scattering-line-dedicated-to-radiobiology-experiments-at-the-trento-proton-therapy-center
#12
F Tommasino, M Rovituso, S Lorentini, C La Tessa, G Petringa, P Cirrone, F Romano, E Scifoni, M Schwarz, M Durante
The recent worldwide spread of Proton Therapy centers paves the way to new opportunities for basic and applied research related to the use of accelerated proton beams. Clinical centers make use of proton beam energies up to about 230 MeV. This represents an interesting energy range for a large spectrum of applications, including detector testing, radiation shielding and space research. Additionally, radiobiology research might benefit for a larger availability of proton beams, especially in those centers where a room dedicated to research activities also exists...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535369/simulation-of-early-radiation-induced-dna-damage-on-different-types-of-cell-nuclei
#13
Nicolas Tang, Marta Bueno, Sylvain Meylan, Sébastien Incerti, Isabelle Clairand, Carmen Villagrasa
This work presents a comparison of simulated early radiation-induced DNA damage represented by yields of double-strand breaks (DSB) in three different human cell nuclei geometries representing fibroblasts, lymphocytes and endothelial cells for protons and alpha particles of different energies and for different irradiation configurations. Each cell nucleus model includes a multi-scale description of the DNA target from the molecular level to the whole human genome representation (6 Gbp) in the G0/G1 phase of the cell cycle and was generated with the DnaFabric software that takes into account the physical, physico-chemical and chemical stages was used to simulate the irradiation of the different cell nuclei...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535354/depth-distributions-of-rbe-weighted-dose-and-photon-isoeffective-dose-for-boron-neutron-capture-therapy
#14
Tatsuhiko Sato, Shin-Ichiro Masunaga, Hiroaki Kumada, Nobuyuki Hamada
Two types of dose were proposed for use in the treatment planning of boron neutron capture therapy (BNCT) for expressing its high relative biological effectiveness (RBE). On one hand, the RBE-weighted dose is the sum of the absorbed doses weighted by fixed RBE for each dose component of BNCT. On the other hand, photon-isoeffective dose is the photon dose to give the same biological effect calculated considering the dose dependence of RBE and the synergetic effect between different types of radiation. In this study, the depth distributions of the two types of dose in a phantom placed at an accelerator-based BNCT field were calculated using Particle and Heavy Ion Transport code System, PHITS, coupled with an extended stochastic microdosimetric kinetic model...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535337/mechanistic-modeling-predicts-anti-carcinogenic-radiation-effects-on-intercellular-signaling-in-vitro-turn-pro-carcinogenic-in-vivo
#15
Pavel Kundrát, Werner Friedland
Oncogenic transformed cells represent an in vitro system mimicking early-stage carcinogenesis. These precancerous cells are subject to a selective removal via apoptosis induced by neighbor cells. By modulating the underpinning intercellular signaling mediated by cytokines and reactive oxygen/nitrogen species, ionizing radiation enhances this removal of precancerous cells in vitro, at doses from a few mGy to a few Gy. However, epidemiological data demonstrate that radiation exposure induces cancer, at least above 100 mGy...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535312/a-hypothesis-of-radioresistance-and-cell-survival-curve-shape-based-on-cell-cycle-progression-and-damage-tolerance
#16
Carsten Herskind, Qi Liu, Xiaolei Liu, Yingying Zhang, Lin Ma, Elsa Angelie, Hui Hui Ma, Junqi Liu, Frank A Giordano, Frederik Wenz, Marlon R Veldwijk
Exponential survival curves of early-passage human fibroblasts challenge classic biophysical models of cell inactivation. Thus, X-ray doses of 2-4 Gy inactivate normal, human skin fibroblasts in spite of negligible residual double-strand breaks. By contrast, radioresistant p53-mutant U251 glioblastoma cells proliferate in spite of residual damage. Similarly, p53 wildtype TK6 lymphoblastoid cells show exponential survival curves while the related p53-mutant WTK1 cell line continued to proliferate and showed a shouldered survival curve...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535311/inter-patient-variability-in-doses-to-nearby-organs-in-breast-cancer-radiotherapy-inference-from-anatomic-features
#17
Pavel Kundrát, Julia Remmele, Hannes Rennau, Sabine Sebb, Cristoforo Simonetto, Markus Eidemüller, Ulrich Wolf, Guido Hildebrandt
With improved cure rates and prolonged patient survival after breast-cancer radiotherapy, radiation-induced second cancers and heart diseases become increasingly important. The heart, lungs and contralateral breast are the most critical organs for these long-term effects. Doses to these organs and hence the risks differ between radiotherapy techniques and especially among patients. To address this variability, treatment plans were generated for 128 early-stage breast-cancer patients using intensity-modulated, 3D-conformal and hybrid radiotherapy...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535286/track-event-theory-a-cell-survival-and-rbe-model-consistent-with-nanodosimetry
#18
Uwe Schneider, Fabiano Vasi, Kevin Schmidli, Jürgen Besserer
A simple model for cell survival which is valid also at high dose has been developed. The model parameters can be traced back to measurable quantities from nanodosimetry. It is assumed that a cell is killed by an event which is defined by two or more double strand breaks in differently sized lethal interaction volumes (LIVs). Two different mechanisms can produce events, one-track events by one-particle track and two-track events by two. One- and two-track events are statistically independent. From the stochastic nature of cell killing which is described by the Poisson distribution, the cell survival probability was derived...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535278/biological-effectiveness-of-lower-energy-photons-for-cancer-risk
#19
D T Goodhead
For risk assessment of photon exposures, the energy-dependence of relative effectiveness may be required. The NCRP has recently addressed this need by reviewing the available evidence from various fields of study and making recommendations for the effectiveness ratio of lower-energy photons, for the purposes of quantitative uncertainty analysis for specific cancer risk assessments where lower-energy photons and electrons are involved. The present paper provides a personal discussion of selected aspects of the evidence and analysis; it highlights the key role of low-energy electrons in determining biological effectiveness...
December 11, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30535246/education-and-training-in-europe-to-support-low-dose-radiation-physics-and-radiobiology
#20
Andrea Ottolenghi, Klaus Trott, Giorgio Baiocco, Vere Smyth
The success of any research programme is dependent on a continuing influx of new expertise, and continuing education to ensure the newest technologies and methods are exploited. In the past decade, a strategic approach has been used to build up the research expertise in the area of radiation protection and risk estimation. The High Level Expert Group (HLEG, www.hleg.de) in their 2009 report on European low-dose research asserted that education and training were key components in the development and maintenance of expertise for research into the risks from low-levels of ionising radiation...
December 11, 2018: Radiation Protection Dosimetry
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