Activity-dependent spinal cord neuromodulation rapidly restores trunk and leg motor functions after complete paralysis.

Epidural electrical stimulation (EES) targeting the dorsal roots of lumbosacral segments restores walking in people with spinal cord injury (SCI). However, EES is delivered with multielectrode paddle leads that were originally designed to target the dorsal column of the spinal cord. Here, we hypothesized that an arrangement of electrodes targeting the ensemble of dorsal roots involved in leg and trunk movements would result in superior efficacy, restoring more diverse motor activities after the most severe SCI.

Impact of head morphology on local brain specific absorption rate from exposure to mobile phone radiation.

Among various possible health effects of mobile phone radiation, the risk of inducing cancer has the strongest interest of laymen and health organizations. Recently, the Interphone epidemiological study investigated the association between the estimated Radio Frequency (RF) dose from mobile phones and the risk of developing a brain tumor. Their dosimetric analysis included over 100 phone models but only two homogeneous head phantoms.

Quantification of RF-exposure of the fetus using anatomical CAD-models in three different gestational stages.

This study analyzes the exposure of pregnant women and their fetuses in three different gestational stages to electromagnetic radiation in the radio frequency range in the near- and the far-field using numerical modeling. For far-field exposure, the power density at which the basic restriction for the whole body SAR is reached is calculated for both the mother and the fetus at whole body resonance and at frequencies between 450 MHz and 2,450 MHz. The near-field exposure is assessed at 450 MHz, 900 MHz, and 2,450 MHz using half wavelength dipoles as generic sources located at different locations around the abdomen of the mother.

Exploration of MR-guided head and neck hyperthermia by phantom testing of a modified prototype applicator for use with proton resonance frequency shift thermometry.

Magnetic resonance thermometry (MRT) offers non-invasive temperature imaging and can greatly contribute to the effectiveness of head and neck hyperthermia. We therefore wish to redesign the HYPERcollar head and neck hyperthermia applicator for simultaneous radio frequency (RF) heating and magnetic resonance thermometry. In this work we tested the feasibility of this goal through an exploratory experiment, in which we used a minimally modified applicator prototype to heat a neck model phantom and used an MR scanner to measure its temperature distribution.

Validation of MR thermometry: method for temperature probe sensor registration accuracy in head and neck phantoms.

Purpose: Magnetic resonance thermometry (MRT) is an attractive means to non-invasively monitor in vivo temperature during head and neck hyperthermia treatments because it can provide multi-dimensional temperature information with high spatial resolution over large regions of interest. However, validation of MRT measurements in a head and neck clinical set-up is crucial to ensure the temperature maps are accurate. Here we demonstrate a unique approach for temperature probe sensor localisation in head and neck hyperthermia test phantoms.

Simulation techniques in hyperthermia treatment planning.

Abstract Clinical trials have shown that hyperthermia (HT), i.e. an increase of tissue temperature to 39-44 °C, significantly enhance radiotherapy and chemotherapy effectiveness [1].

Clinical integration of software tool VEDO for adaptive and quantitative application of phased array hyperthermia in the head and neck.

Background And Purpose: In Rotterdam, patient-specific hyperthermia (HT) treatment planning (HTP) is applied for all deep head and neck (H&N) HT treatments. In this paper we introduce VEDO (the Visualisation Tool for Electromagnetic Dosimetry and Optimisation), the software tool required, and demonstrate its value for HTP-guided online complaint-adaptive (CA) steering based on specific absorption rate (SAR) optimisation during a H&N HT treatment.

Materials And Methods: VEDO integrates CA steering, visualisation of the SAR patterns and mean tumour SAR (SAR(target)) optimisation in a single screen.

Analysis of human brain exposure to low-frequency magnetic fields: a numerical assessment of spatially averaged electric fields and exposure limits.

Compliance with the established exposure limits for the electric field (E-field) induced in the human brain due to low-frequency magnetic field (B-field) induction is demonstrated by numerical dosimetry. The objective of this study is to investigate the dependency of dosimetric compliance assessments on the applied methodology and segmentations. The dependency of the discretization uncertainty (i.

Exposure of the human body to professional and domestic induction cooktops compared to the basic restrictions.

We investigated whether domestic and professional induction cooktops comply with the basic restrictions defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Based on magnetic field measurements, a generic numerical model of an induction cooktop was derived in order to model user exposure. The current density induced in the user was simulated for various models and distances.

A patch antenna design for application in a phased-array head and neck hyperthermia applicator.

In this paper, we describe a specifically designed patch antenna that can be used as the basis antenna element of a clinical phased-array head and neck hyperthermia applicator. Using electromagnetic simulations we optimized the dimensions of a probe-fed patch antenna design for operation at 433 MHz. By several optimization steps we could converge to a theoretical reflection of -38 dB and a bandwidth (-15 dB) of 20 MHz (4.

A head and neck hyperthermia applicator: theoretical antenna array design.

Purpose: Investigation into the feasibility of a circular array of dipole antennas to deposit RF-energy centrally in the neck as a function of: (1) patient positioning, (2) antenna ring radius, (3) number of antenna rings, (4) number of antennas per ring and (5) distance between antenna rings.

Materials And Methods: Power absorption (PA) distributions in realistic, head and neck, anatomy models are calculated at 433 MHz. Relative PA distributions corresponding to different set-ups were analysed using the ratio of the average PA (aPA) in the target and neck region.

Electromagnetic head-and-neck hyperthermia applicator: experimental phantom verification and FDTD model.

Purpose: To experimentally verify the feasibility of focused heating in the neck region by an array of two rings of six electromagnetic antennas. We also measured the dynamic specific absorption rate (SAR) steering possibilities of this setup and compared these SAR patterns to simulations.

Methods And Materials: Using a specially constructed laboratory prototype head-and-neck applicator, including a neck-mimicking cylindrical muscle phantom, we performed SAR measurements by electric field, Schottky-diode sheet measurements and, using the power-pulse technique, by fiberoptic thermometry and infrared thermography.