Indoor radon exposure and lung cancer risk: a meta-analysis of case-control studies

The aim of this study was to assess a potential relationship between indoor radon exposure and the incidence of lung cancer worldwide. A systematic literature search was carried out in PubMed, Web of Science, and Google Scholar to identify relevant studies published in English conducted in the last 15 years until January 2016. Summary relative risks (RR) and the corresponding 95% confidence intervals (CIs) were calculated using a random-effects model and the influence of moderators using a mixed-effects model. Heterogeneity was assessed using the Q, I2 and H2 tests, and the source of heterogeneity was detected by meta-regression analysis. Publication bias was evaluated with Egger’s regression symmetry test and the contour-enhanced funnel plot. Leave-one-out sensitivity analysis was performed. Twenty-five lung cancer studies (case-control studies) with 13,569 cases and 22,701 controls were included. Indoor Radon exposure was significantly associated with increased risk for lung cancer (RR, 1.19; 95% CI, 1.02–1.39). Study location analysis showed that radon exposure was associated with increased risk for lung cancer from forty degrees absolute latitude (RR, 1.09; 95% CI, 0.92–1.31), to fifty degrees (RR 1.26; 95% CI, 1.08–1.48), to sixty degrees (RR, 1.46; 95% CI, 1.12–1.91). Indoor radon exposure may be associated with increased risk for lung cancer

Preliminary test of Bragg application for proton therapy using the Geant4 toolkit

In the treatment of tumors, the advantage of proton therapy is the sparing of dose to healthy tissue surrounding the target one, saving it from unnecessary damage. For protons, the dose increases with increasing penetration depth up to the Bragg peak that occurs near the end of the particle’s range. This work shows the first results obtained with a specific application, Bragg, which has been developed with the use of the Geant4 package. This application aims to contribute to develop and test innovative treatment planning models for particle therapy. The results from the numerical simulation have been compared with the experimental data in the literature. The validation of models against experimental data is a prerequisite for the use of any application and, therefore, highly demanded

Protons Interaction with Nomex Target: Secondary Radiation from a Monte Carlo Simulation with Geant4

The study of suitable materials to shield astronauts from Galactic Cosmic Rays (GCR) is a topic of fundamental importance. The choice of the material must take into account both the secondary radiation produced by the interaction between primary radiation and material and its shielding ability. The physics case presented here deals with the interaction of a proton beam with a Nomex shield, namely, a target material with a mass thickness of 20 g cm−2. The study was conducted with the simulation code DOSE based on the well-known simulation package Geant4. This article shows the properties of secondary radiations produced in the target by the interaction of a proton beam in an energy range characterizing the GCR spectrum. We observed the production of ions of masses and charges lower than the chemical elements that make up Nomex, and also a significant production of neutrons, protons, and particles

Gini Method Application: Indoor Radon Survey in Kpong, Ghana

In this study, the indoor radon concentrations map, starting from a sparse measurements survey, was realized with the Gini index method. This method was applied on a real dataset coming from indoor radon measurements carried out in Kpong, Ghana. The Gini coefficient variogram is shown to be a good estimator of the inhomogeneity degree of radon concentration because it allows for better constraining of the critical distance below which the radon geological source can be considered as uniform. The indoor radon measurements were performed in 96 dwellings in Kpong, Ghana. The data showed that 84% of the residences monitored had radon levels below 100 Bqm¯³, versus 16% having levels above the World Health Organization's (WHO) suggested reference range (100 Bqm¯³). The survey indicated that the average indoor radon concentration (IRC) was 55 ± 36 Bqm¯³. The concentrations range from 4–176 Bqm¯³. The mean value 55 Bqm¯³ is 38% higher than the world's average IRC of 40 Bqm¯³ (UNSCEAR, 1993)

Validation of the Electromagnetic Physical Processes with Software SPENVIS

The Space Radiation represents a serious risk for astronauts during space missions. The risk related to the space radiation exposure could involve acute and/or late effects. The Solar Cosmic Radiation that consists of protons (≈98%) with a very wide spectrum in energy (up to several GeV), is the major source of exposure for the crew. In this paper we present the results of the validation of the electromagnetic physical processes with the aim to contribute to the study of radiation protection for astronauts, in particular against the radiation due to the Solar Particle Events (SPE). The simulation was performed using MULASSIS, a module to the software SPENVIS, with protons as source, in the energy range from 800 MeV to 1.2 GeV, on a slab of aluminum of mass thickness of 20 g/cm2. The results obtained by the simulation were compared with PSTAR database of the NIST. Finally, a comparison between SPENVIS and Geant4-9.6p2 was performed

Nomex with boron as a neutron shielding in space: Preliminary study

In this work we present a study devoted to the evaluation of the efficiency of a radiation shield, made out of the Nomex material doped with boron, in reducing the absorbed dose after bombardment with a 1GeV proton beam. This study is relevant to the definition of optimal conditions for the shielding of astronauts from Solar Particle Events and Galactic Cosmic Radiation in space. Nomex shield is treated with boron at different concentrations. The production and transport of radiation produced after proton interaction is treated with a simulation tool based on Geant4. The added boron acts as an effective neutron mitigating material. The main preliminary result is that the average dose changes effectively despite the additional production of alpha particles from the reaction 10B(n,α)

A new geostatistical tool for the analysis of the geographical variability of the indoor radon activity

AbstractThe population is continuously exposed to a background level of ionizing radiation due to the natural radioactivity and, in particular, with radon (222Rn). Radon gas has been classified as the second leading cause of lung cancer after tobacco smoke [1]. In the confined environment, radon concentration can reach harmful level and vary accordingly to many factors. Since the primary source of radon in dwellings is the subsurface, the risk assessment and reduction cannot disregard the identification of the local geology and the environmental predisposing factors. In this article, we propose a new methodology, based on the computation of the Gini coefficients at different spatial scales, to estimate the spatial correlation and the geographical variability of radon concentrations. This variability can be interpreted as a signature of the different subsurface geological conditions. The Gini coefficient computation is a statistical tool widely used to determine the degree of inhomogeneity of different kinds of distributions. We generated several simulated radon distributions, and the proposed tool has been validated by comparing the variograms based on the semi-variance computation with those ones based on the Gini coefficient. The Gini coefficient variogram is shown to be a good estimator of the inhomogeneity degree of radon concentration. Indeed, it allows to better constrain the critical distance below which the radon geological source can be considered as uniform at least for the investigated length scales of variability; it also better discriminates the fluctuations due to the environmental predisposing factors from those ones due to the random spatially uncorrelated noise

Initial Testing of an Approximated, Fast Calculation Procedure for Personalized Dosimetry in Radionuclide Therapy Based on Planar Whole-Body Scan and Monte-Carlo Specific Dose Rates from the OpenDose Project

Individualized dosimetry in nuclear medicine is currently at least advisable in order to obtain the best risk–benefit balance in terms of the maximal dose to lesions and under-threshold doses to radiosensitive organs. This article aims to propose a procedure for fast dosimetric calculations based on planar whole-body scintigraphy (WBS) images and developed to be employed in everyday clinical practice. Methods: For simplicity and legacy reasons, the method is based on planar imaging dosimetry, complemented with some assumptions on the radiopharmaceutical kinetics empirically derived from single-photon emission tomography/computed tomography (SPECT/CT) image analysis. The idea is to exploit a rough estimate of the time-integrated activity as has been suggested for SPECT/CT dosimetry but using planar images. The resulting further reduction in dose estimation accuracy is moderated by the use of a high-precision Monte-Carlo S-factor, such as those available within the OpenDose project. Results: We moved the problem of individualized dosimetry to a transformed space where comparing doses was imparted to the ICRP Average Male/Female computational phantom, resulting from an activity distribution related to patient’s pharmaceutical uptake. This is a fast method for the personalized dosimetric evaluation of radionuclide therapy, bearing in mind that the resulting doses are meaningful in comparison with thresholds calculated in the same framework. Conclusion: The simplified scheme proposed here can help the community, or even the single physician, establish a quantitative guide-for-the-eye approach to individualized dosimetry

Acute Delta Hepatitis in Italy spanning three decades (1991–2019): Evidence for the effectiveness of the hepatitis B vaccination campaign

Updated incidence data of acute Delta virus hepatitis (HDV) are lacking worldwide. Our aim was to evaluate incidence of and risk factors for acute HDV in Italy after the introduction of the compulsory vaccination against hepatitis B virus (HBV) in 1991. Data were obtained from the National Surveillance System of acute viral hepatitis (SEIEVA). Independent predictors of HDV were assessed by logistic-regression analysis. The incidence of acute HDV per 1-million population declined from 3.2 cases in 1987 to 0.04 in 2019, parallel to that of acute HBV per 100,000 from 10.0 to 0.39 cases during the same period. The median age of cases increased from 27 years in the decade 1991-1999 to 44 years in the decade 2010-2019 (p < .001). Over the same period, the male/female ratio decreased from 3.8 to 2.1, the proportion of coinfections increased from 55% to 75% (p = .003) and that of HBsAg positive acute hepatitis tested for by IgM anti-HDV linearly decreased from 50.1% to 34.1% (p < .001). People born abroad accounted for 24.6% of cases in 2004-2010 and 32.1% in 2011-2019. In the period 2010-2019, risky sexual behaviour (O.R. 4.2; 95%CI: 1.4-12.8) was the sole independent predictor of acute HDV; conversely intravenous drug use was no longer associated (O.R. 1.25; 95%CI: 0.15-10.22) with this. In conclusion, HBV vaccination was an effective measure to control acute HDV. Intravenous drug use is no longer an efficient mode of HDV spread. Testing for IgM-anti HDV is a grey area requiring alert. Acute HDV in foreigners should be monitored in the years to come

Protons Interaction with Nomex Target: Secondary Radiation from a Monte Carlo Simulation with Geant4

The study of suitable materials to shield astronauts from Galactic Cosmic Rays (GCR) is a topic of fundamental importance. The choice of the material must take into account both the secondary radiation produced by the interaction between primary radiation and material and its shielding ability. The physics case presented here deals with the interaction of a proton beam with a Nomex shield, namely, a target material with a mass thickness of 20 g cm−2. The study was conducted with the simulation code DOSE based on the well-known simulation package Geant4. This article shows the properties of secondary radiations produced in the target by the interaction of a proton beam in an energy range characterizing the GCR spectrum. We observed the production of ions of masses and charges lower than the chemical elements that make up Nomex, and also a significant production of neutrons, protons, and 𝛼 particles