In vivo electrical conductivity imaging of animal tumor model at 7T using electrical properties tomography

Ex vivo studies have shown that various diseases alter the electrical properties of tissues compared to healthy nearby tissues. Therefore, electrical conductivity can be used as a diagnostic parameter for e.g. tumor diagnosis. For in vivo measurements, magnetic resonance electrical properties tomography (MREPT) was used and electrical conductivity was reconstructed from the B1+ phase. The technique was first evaluated using homogeneous and heterogeneous phantoms. Then a mouse with a tumor was scanned and the conductivity is reconstructed from the B1+ phase map. The reconstructed conductivity in the phantom experiments was in good agreement with the target conductivity map and the conductivity map of the animal revealed good agreement with the co-axial probe measurement. Our work confirms the possibility of accurate in vivo conductivity assessment in disease

Design and calibration of a mm-wave personal exposure meter for 5G exposure assessment in indoor diffuse environments

For the first time, a mm-wave personal exposure meter (mm-PEM) for the 5th generation of mobile networks (5G) exposure assessment in indoor diffuse fields is presented. The design is based on simulations and on-phantom calibration measurements in a mm-wave reverberation chamber (RC) at 60 GHz. The mm-PEM consists of an array of nine antennas on the body. Using the mm-PEM, the incident power density (IPD) is measured in the unloaded RC, for the antenna(s) on the phantom and RC loaded with phantom. The uncertainty of the mm-PEM is then determined in terms of its response, which is defined as the ratio of antenna aperture for the above measurement scenarios. Using nine antennas, the designed meter has a response of 1.043 (0.17 dB) at 60 GHz, which is very close to 1 (0 dB), the desired ideal response value. The mm-PEM measured an IPD of 96.6 W m(-2) at 60 GHz in the RC, for an input power of 1 W. In addition, the average absorption cross-section of the phantom is determined as 225 cm(2), which is an excellent agreement with its physical dimensions

Human Exposure Assessment in Indoor Environments Using A 60 GHz Personal Exposure Meter

International audienceSHORT ABSTRACT This paper presents the first mm-wave personal exposure meter (mm-PEM) to assess human exposure to the 5th generation of mobile networks (5G) in indoor environments. The mm-PEM consists of 9 elements of an antenna array and is calibrated on a skin-equivalent phantom in a reverberation chamber at 60 GHz. The designed mm-PEM has a response of 1.043 (0.17 dB) at 60 GHz which is very close to the desired response of a PEM i.e. 1 (0 dB). The mm-PEM measured an incident power density of 41 mW.m-2 at 60 GHz for an input power of 1 mW in the empty chamber. INTRODUCTION The rapid progress in 60-GHz wireless technologies and the availability of the 5th generation of mobile networks (5G) in the near future [1] has raised concerns regarding the potential adverse health effects of mm-waves on human body. The absorption of mm-waves is limited to skin tissues [1]. Therefore, the incident power density (IPD) is studied as a dosimetric quantity. The safety limits of IPD are 1 mW.cm-2 and 5 mW.cm-2 averaged over 20 cm 2 of the exposed area for general public and occupational exposure, respectively [2]. Human exposure to radiofrequency (RF) electromagnetic fields is usually measured by Personal Exposimeters (PEMs) [3, 4]. These are portable devices worn on body allowing for continuous measurement of the electric fields strength in several frequency bands for which protocols have been developed [5]. PEMs are calibrated in free space while used on body. In other words, the measured values are compromised by the presence of the human body and thus have large measurement uncertainties [6]. In order to reduce this measurement uncertainty, personal distributed exposimeters (PDE) with multiple antennas can be used for single [7] and multi telecommunication bands [8]. Research shows that people spend more than 80% of their times indoors [9]. This could increase human exposure the electromagnetic fields. The total power in an indoor environment consists of specular and diffuse multipath components. The former and the latter are due to the reflections from large surfaces and presence of objects in a room, respectively. The DMC can contribute up to 95% to the total power density in an indoor environment [10]