Identification of factors influencing the Whole Body Absorption Rate using statistical analysis

To protect people from Electromagnetic Fields (EMF), ICNIRP has defined limits. The fundamental ones are the Basic Restrictions (BRs) [1]. The BRs determine the maximum values (averaged over the whole body and averaged over 10 grams of tissues) of Specific Absorption Rate (SAR). Since BRs can be complex to assess ICNIRP has also defined derived value: the reference levels (RLs). These RLs were established to guaranty the compliance to the BRs. Several studies with human model voxels (a.k.a. phantoms) show that even below the RLs, the WBSAR (Whole Body average SAR) may exceed the BRs due to the variability of human morphology [2]. In this paper we will identify the morphological factors influencing the WBSAR in the case of a frontal plane wave exposure at the frequency of 2100MHz in isolated conditions and vertical polar. The method is based on the construction of a model that makes it possible to estimate the statistical distribution of the WBSAR for a given human population

Identification des facteurs morphologiques impactant le Débit d'Absorption Spécifique du Corps Entier

Les systèmes fondés sur des technologies liées aux champs électromagnétiques (EM) sont de plus en plus répandus. La question des effets possibles sur la santé dus à ces technologies sont devenues une préoccupation publique. Afin de limiter l'exposition des personnes aux ondes EM, des niveaux de protection appelés restrictions de bases, ont été définis par l'ICNIRP [1]. Ces niveaux fixent des valeurs de Débit d'Absorption Spécifique (Specific Absorption Rate : SAR) à ne pas dépasser. Des niveaux de références ont été dérivés des restrictions de base de façon conservative. Plusieurs études menées avec des modèles numériques d'humains [2,3] (fantômes) montrent que, pour certaines configurations, le WBSAR (Whole Body averged Specific Absorption Rate) est très proche des restrictions de base. D'autres études ont souligné la variabilité du WBSAR due à la variabilité de la morphologie humaine [2]. L'objectif de ce papier est d'identifier les facteurs morphologiques (internes et externes) qui ont un impact sur le WBSAR pour des fantômes exposés à une onde plane à une fréquence fixée à 2100MHz et une densité de puissance de 1W/m²

Bayesian experiment planning applied to numerical dosimetry

To protect people from electromagnetic field, Basic Restrictions (BR) are defined [1]. These BR fix a limit to be not exceeded. The metric associated with these BR is the Specific Absorption Rate (SAR). Reference Levels (RL) are also defined since the BR are difficult to check in situ. These RL set the maximum allowed electromagnetic field. The compliance to RL guaranties the compliance to BR. To evaluate the SAR in the human body, some anatomical models (phantoms) and numerical methods are used (e.g. Finite Difference in Time Domain). Based on this, studies show that for some configurations the Whole Body SAR (WBSAR) is close to BR. Other studies stressed the variability of the WBSAR due to the variability of human morphology [2]. Despite the computing resources development, the number of the phantoms is very limited. This limited number of phantoms does not allow using usual method such as Monte Carlo to assess the maximal threshold of the WBSAR for a given population. Hence the construction of a model of the WBSAR as a function of morphology is required. Nevertheless, the WBSAR is impacted by the external morphology (height and weight) and the internal morphology (proportion of fat, proportion of muscles...). But there is no statistical data concerning the internal ones. In this paper, the external morphology is focused and the internal morphology is released by considering homogeneous phantoms. A Bayesian sequential experiment planning is proposed. This method consists in refining the region of interest of the WBSAR statistical distribution for a given population. This region of interest is the threshold of the WBSAR at 95% (WBSAR95). This study is conducted in the case of a plane wave vertically polarized and frontally oriented on phantoms. The incident power is equal to 1W/m². The frequency is fixed at 2.1GHz

Analyse statistique de la puissance absorbée par le corps entier en radiofréquence

Dans ce papier, nous proposons une identification des facteurs morphologiques qui peuvent impacter le Débit d'Absorption Spécifique (DAS) du corps entier dans le cas d'une onde plan. Cette étude compare différents modèles mathématiques et conclue l'analyse des données par des tests statistiques. Sous certaines hypothèses aussi une approche permettant de quantifier le quantile à 95% du DAS pour le corps entier est enfin proposée

Plan d'expériences séquentiel appliqué à la dosimétrie numérique

Dans ce papier nous allons proposer une méthodologie consistant à trouver la valeur du Débit d'Absorption Spécifique du Corps Entier (DAS_CE) qui couvre 95% d'une population donnée. Cette méthode repose d'une part sur de l'Inférence Bayesienne et d'autre part sur un modèle paramétrique de prédiction du DAS_CE en fonction de la morphologie ainsi que des outils de simulations numériques

Gender-related and geographic trends in interactions between radiotherapy professionals on Twitter.

BACKGROUND AND PURPOSE Twitter presence in academia has been linked to greater research impact which influences career progression. The purpose of this study was to analyse Twitter activity of the radiotherapy community around ESTRO congresses with a focus on gender-related and geographic trends. MATERIALS AND METHODS Tweets, re-tweets and replies, here designated as interactions, around the ESTRO congresses held in 2012-2021 were collected. Twitter activity was analysed temporally and, for the period 2016-2021, the geographical span of the ESTRO Twitter network was studied. Tweets and Twitter users collated during the 10 years analysed were ranked based on number of 'likes', 're-tweets' and followers, considered as indicators of leadership/influence. Gender representation was assessed for the top-end percentiles. RESULTS Twitter activity around ESTRO congresses was multiplied by 60 in 6 years growing from 150 interactions in 2012 to a peak of 9097 in 2018. In 2020, during the SARS-CoV-2 pandemic, activity dropped by 60 % to reach 2945 interactions and recovered to half the pre-pandemic level in 2021. Europe, North America and Oceania were strongly connected and remained the main contributors. While overall, 58 % of accounts were owned by men, this proportion increased towards top liked/re-tweeted tweets and most-followed profiles to reach up to 84 % in the top-percentiles. CONCLUSION During the SARS-CoV-2 pandemic, Twitter activity around ESTRO congresses substantially decreased. Men were over-represented on the platform and in most popular tweets and influential accounts. Given the increasing importance of social media presence in academia the gender-based biases observed may help in understanding the gender gap in career progression

Three-dimensional MRI-based treatment planning approach for non-invasive ocular proton therapy

Purpose: To develop a high-resolution three-dimensional (3D) magnetic resonance imaging (MRI)-based treatment planning approach for uveal melanomas (UM) in proton therapy. Materials/methods: For eight patients with UM, a segmentation of the gross tumor volume (GTV) and organs-at-risk (OARs) was performed on T1- and T2-weighted 7 Tesla MRI image data to reconstruct the patient MR-eye. An extended contour was defined with a 2.5-mm isotropic margin derived from the GTV. A broad beam algorithm, which we have called πDose, was implemented to calculate relative proton absorbed doses to the ipsilateral OARs. Clinically favorable gazing angles of the treated eye were assessed by calculating a global weighted-sum objective function, which set penalties for OARs and extreme gazing angles. An optimizer, which we have named OPT’im-Eye-Tool, was developed to tune the parameters of the functions for sparing critical-OARs. Results: In total, 441 gazing angles were simulated for every patient. Target coverage including margins was achieved in all the cases (V95% > 95%). Over the whole gazing angles solutions space, maximum dose (Dmax) to the optic nerve and the macula, and mean doses (Dmean) to the lens, the ciliary body and the sclera were calculated. A forward optimization was applied by OPT’im-Eye-Tool in three different prioritizations: iso-weighted, optic nerve prioritized, and macula prioritized. In each, the function values were depicted in

Folding of Matrix Metalloproteinase-2 Prevents Endogenous Generation of MHC Class-I Restricted Epitope

BACKGROUND: We previously demonstrated that the matrix metalloproteinase-2 (MMP-2) contained an antigenic peptide recognized by a CD8 T cell clone in the HLA-A*0201 context. The presentation of this peptide on class I molecules by human melanoma cells required a cross-presentation mechanism. Surprisingly, the classical endogenous processing pathway did not process this MMP-2 epitope. METHODOLOGY/PRINCIPAL FINDINGS: By PCR directed mutagenesis we showed that disruption of a single disulfide bond induced MMP-2 epitope presentation. By Pulse-Chase experiment, we demonstrated that disulfide bonds stabilized MMP-2 and impeded its degradation. Finally, using drugs, we documented that mutated MMP-2 epitope presentation used the proteasome and retrotranslocation complex. CONCLUSIONS/SIGNIFICANCE: These data appear crucial to us since they established the existence of a new inhibitory mechanism for the generation of a T cell epitope. In spite of MMP-2 classified as a self-antigen, the fact that cross-presentation is the only way to present this MMP-2 epitope underlines the importance to target this type of antigen in immunotherapy protocols

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon