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Introduction
Skills and Expertise
Publications
Publications (109)
Objective:
Non-invasive brain stimulation (NIBS) methodologies, such as transcranial electric (tES) are increasingly employed for therapeutic, diagnostic, or research purposes. The concurrent presence of active/passive implants can pose safety risks, affect the NIBS delivery, or generate confounding signals. A systematic investigation is required...
Objective: Non-invasive brain stimulation (NIBS) methodologies, such as transcranial electric (tES) and magnetic stimulation are increasingly employed for therapeutic, diagnostic, or research purposes. The concurrent presence of active or passive implants can pose safety risks, affect the NIBS delivery, or generate confounding signals. A systematic...
Objective:
The clinical management of several neurological disorders benefits from the assessment of intracranial pressure and craniospinal compliance. However, the associated procedures are invasive in nature. Here, we aimed to assess whether naturally occurring periodic changes in the dielectric properties of the head could serve as the basis fo...
Purpose
Healthy tissue hotspots are a main limiting factor in administering deep hyperthermia cancer therapy. We propose an optimization scheme that uses time-multiplexed steering (TMPS) among minimally correlated (nearly) Pareto-optimal solutions to suppress hotspots without reducing tumor heating. Furthermore, tumor heating homogeneity is maximiz...
In order to achieve an integrated radio-frequency electromagnetic fields (RF-EMF) dose assessment, detailed information about source-specific exposure duration and output power is needed. We developed an Integrated Exposure Model (IEM) to combine energy absorbed due to use of and exposure to RF-EMF sources and applied it to a sample of the general...
Objective
To investigate the association of estimated all-day and evening whole-brain radiofrequency electromagnetic field (RF-EMF) doses with sleep disturbances and objective sleep measures in preadolescents.
Methods
We included preadolescents aged 9–12 years from two population-based birth cohorts, the Dutch Generation R Study (n = 974) and the...
We present a simulation study investigating the feasibility of electrical impedance tomography (EIT) as a low cost, noninvasive technique for hyperthermia (HT) treatment monitoring and adaptation. Temperature rise in tissues leads to perfusion and tissue conductivity changes that can be reconstructed in 3D by EIT to noninvasively map temperature an...
Background
Little is known about radiofrequency electromagnetic fields (RF) from mobile technology and resulting dose in young people. We describe modeled integrated RF dose in European children and adolescents combining own mobile device use and surrounding sources.
Methods
Using an integrated RF model, we estimated the daily RF dose in the brain...
Objective
To investigate the association between estimated whole-brain radiofrequency electromagnetic fields (RF-EMF) dose, using an improved integrated RF-EMF exposure model, and cognitive function in preadolescents and adolescents.
Methods
Cross-sectional analysis in preadolescents aged 9–11 years and adolescents aged 17–18 years from the Dutch...
The specific absorption rate (SAR) induced by wireless radiofrequency (RF) systems depends on different parameters. Previously, SAR was mainly assessed under conditions of a single frequency and technology and for a limited number of localized RF sources. The current and emerging mobile systems involve a wider range of usage scenarios and are frequ...
Objective
To assess the association between estimated whole-brain and lobe-specific radiofrequency electromagnetic fields (RF-EMF) doses, using an improved integrated RF-EMF exposure model, and brain volumes in preadolescents at 9–12 years old.
Methods
Cross-sectional analysis in preadolescents aged 9–12 years from the Generation R Study, a popula...
Modulated electromagnetic fields (wEMFs), as generated by modern communication technologies, have raised concerns about adverse health effects. The International Agency for Research on Cancer (IARC) classifies them as "possibly carcinogenic to humans" (Group 2B), yet, the underlying molecular mechanisms initiating and promoting tumorigenesis remain...
To date, the development of valid and globally universally accepted recognized methods for the accurate exposure assessment of wireless power transfer (WPT) technologies is lagging behind the rapid emergence of high power systems in the energy and automotive sectors. WPT systems based on inductive and magnetic resonance technologies generate strong...
Background:
Administration of amplitude modulated 27·12 MHz radiofrequency electromagnetic fields (AM RF EMF) by means of a spoon-shaped applicator placed on the patient's tongue is a newly approved treatment for advanced hepatocellular carcinoma (HCC). The mechanism of action of tumour-specific AM RF EMF is largely unknown.
Methods:
Whole body...
Many mobile devices, including wireless microphones, are operated in the near proximity of the human body that modifies radiation conditions and absorbs some of the power of the device and, therefore, introduces an additional loss (body loss) to the radio communication link. In this article, we characterize the body loss in wireless microphones ove...
Exposure assessments in the frequency range above 10 GHz typically require knowledge of the power density very close to the radiator (at 2-mm distance), which can be obtained through the total electric and magnetic fields. However, phase measurements are often not feasible in this frequency range, in particular in the reactive near field. We develo...
The cover image, by S. Dressel et al., is based on the Original Article Novel hyperthermia applicator system allows adaptive treatment planning: Preliminary clinical results in tumour‐bearing animals, DOI: 10.1111/vco.12340
Radiofrequency radiation (RFR) causes heating, which can lead to detrimental biological effects. To characterize the effects of RFR exposure on body temperature in relation to animal size and pregnancy, a series of short-term toxicity studies was conducted in a unique RFR exposure system. Young and old B6C3F1 mice and young, old, and pregnant Harla...
Background/aim
The daily dose of radio-frequency electromagnetic fields (RF-EMF) received by the human body depends on source, use, and body characteristics. We developed a model capable of estimating total RF-EMF dose (J/kg) for 64 body tissues as well as the contribution of specific sources to total dose based on personal characteristics, source...
332
Background: Amplitude-modulated 27.12 MHz radiofrequency electromagnetic fields (AM RF EMF) delivered via a spoon-shaped antenna placed on the patient’s tongue result in shrinkage of the primary and metastatic tumors in patients with advanced hepatocellular carcinoma (HCC). (Costa FP, et al. Br J Cancer. 2011;105:640-648.) The mechanism by whic...
p>Background/aim The daily dose of radio-frequency electromagnetic fields (RF-EMF) received by the human body depends on source, use, and body characteristics. We developed a model capable of estimating total RF-EMF dose (J/kg) for 64 body tissues as well as the contribution of specific sources to total dose based on personal characteristics, sourc...
Electromagnetic fields are ubiquitous in the environment. Human exposure to intermediate frequency (IF) fields is increasing due to applications like electronic article surveillance systems, wireless power transfer, and induction heating cooking hobs. However, there are limited data on possible health effects of exposure to IF magnetic fields (MF)....
Hyperthermia (HT) as an adjuvant to radiation therapy (RT) is a multimodality treatment method to enhance therapeutic efficacy in different tumours. High demands are placed on the hardware and treatment planning software to guarantee adequately planned and applied HT treatments. The aim of this prospective study was to determine the effectiveness a...
Supplementary material
Human exposure to intermediate frequency (IF) fields is increasing due to new applications such as electronic article surveillance systems, wireless power transfer and induction heating cookers. However, limited data is available on effects of IF magnetic fields (MF) on male fertility function. This study was conducted to assess possible effects on...
In this paper, we present the detailed life-time dosimetry analysis for rodents exposed in the reverberation exposure system designed for the two-year cancer bioassay study conducted by the National Toxicology Program of the National Institute of Environmental Health Sciences. The study required the well-controlled and characterized exposure of ind...
A measurement technique and apparatus for electrically small antennas employing miniature photonically powered radio-frequency over fibre links to ensure minimum electrical footprint of the measurement device. The challenge to achieve accurate measurements of electrically small antennas for communications bands up to 6 GHz is demonstrated along wit...
The goal of this study was to quantify the degradation in wireless microphone transmission performances at higher frequencies as compared to the performances in the currently allocated UHF band, with particular reference to how the radiation pattern of wireless microphones in the presence of a human body changes as the transmission frequency increa...
We describe a method to correlate E-fields induced by exposure to extremely low frequency magnetic fields in laboratory mice and rats during in vivo experiments to those induced in children. Four different approaches of mapping relative dose rates between humans and rodents are herein proposed and analyzed. Based on these mapping methods and volume...
An exposure system that addresses difficulties that arise for exposure of small animals at low frequencies with a high exposure level is presented. The system, intended to operate at 27 MHz, consists of two identical transverse electro-magnetic (TEM) cells for exposure and sham exposure of groups of 16 free-running mice housed in pairs within stand...
Exposure to extremely low-frequency magnetic fields (ELF-MF) was evaluated in an International Agency for Research on Cancer (IARC) Monographs as "possibly carcinogenic to humans" in 2001, based on increased childhood leukemia risk observed in epidemiological studies. We conducted a hazard assessment using available scientific evidence published be...
Thesis (Ph. D.)--University of Wales (U.C.N.W., Bangor: Electronic Engineering Science), 1991.
This paper describes a new approach to the risk assessment of exposure from wireless network devices, including an exposure setup and dosimetric assessment for in vivo studies. A novel desktop reverberation chamber has been developed for well-controlled exposure of mice for up to 24 h per day to address the biological impact of human exposure scena...
The Recommendation 1999/529/EU and the Directive 2013/35/EU suggest limits for both general public and occupational exposures
to extremely low-frequency magnetic fields, but without special limits for pregnant women. This study aimed to assess the
compliance of pregnant women to the current regulations, when exposed to uniform MF at 50 Hz (100 μT f...
An experimental rectangular thorax prototype is proposed for multistage pneumothorax diagnosis. Two patch antennas are applied on-body to monitor air layer between the lung and chest wall. The prototype consists of semi-solid and liquid materials corresponding to skin, fat, air and lung layers from 1 to 4 GHz, where the diagnostic sensor operates....
An experimental system that is capable of characterizing the RF-induced heating of active implantable medical devices is developed. The system is used to experimentally characterize the local RF-induced heating of generic implants and the obtained experimental results are compared with numerical results obtained from full-wave computational electro...
In this paper, fetal exposure to uniform magnetic fields (MF) with different polarizations is quantified at 50 Hz. Numerical computations were performed on high-resolution pregnant models at 3, 7, and 9 months of gestational age (GA), that distinguish a high number of fetal tissues. Fetal whole-body and tissue-specific induced electric fields (E) a...
In this paper, we present a detailed life time dosimetry analysis for individually housed rodents exposed to radio frequency (RF) signals. This long term investigation is part of the toxicity and carcinogenicity study on cell phone radiation funded by the National Toxicology Program of the National Institute of Environmental Health Sciences. We exp...
In this paper, a novel applicator for hyperthermia treatment is presented providing a significantly improved quality assurance for the treatment. An improved method has been developed to measure the total incident field (amplitude and phase) and the power absorbed (SAR) by the tissues from each applicator element, based on integrated sensors and da...
Background
The influence of electromagnetic fields on the health of humans and animals is still an intensively discussed and scientifically investigated issue (Prakt Tierarzt 11:15-20, 2003; Umwelt Medizin Gesellschaft 17:326-332, 2004; J Toxicol Environment Health, Part B 12:572–597, 2009). We are surrounded by numerous electromagnetic fields of v...
The objective of this paper is to extend the dosimetric assessment of 35mm Petri dishes exposed in the standing wave of R18 waveguides operated at 1950MHz for a medium-oil two-layer configuration for cells in monolayer and suspension. The culture medium inside the Petri dish is covered by oil that prevents evaporation and seals the cells below in t...
Purpose:
This article investigates the safety of radiofrequency induced local thermal hotspots within a 1.5T body coil by assessing the transient local peak temperatures as a function of exposure level and local thermoregulation in four anatomical human models in different Z-positions.
Methods:
To quantize the effective thermal stress of the tis...
A programmable system has been developed for the study of both transient and persistent effects of extremely low frequency (ELF) magnetic field exposure of cell cultures. This high-precision exposure system enables experimental blinding and fully characterized exposure while simultaneously allowing live cell imaging. It is based on a live imaging c...
The development of scientifically sound instrumentation, methods, and procedures for the electromagnetic exposure assessment of compact fluorescent lamps (CFLs) is investigated. The incident and induced fields from 11 CFLs have been measured in the 10 kHz-1 MHz range, and they are compared with the levels for incandescent and light emitting diode (...
A project is described that is developing procedures and instrumentation to demonstrate compliance with EU Directive 2004/40/EC. In 2012, the directive will pose new requirements on employers in the European Union to evaluate the exposure of workers to electromagnetic fields (EMF). Implementation of these requirements is a significant challenge to...
Both a novel hyperthermia treatment planning tool and a new head&neck applicator have been developed to overcome limitations of existing approaches. The treatment planning tool is optimized for high quality, accurate, realistic simulations of highly detailed models. The applicator offers superior steerability and online control.
Investigations have been carried out to determine the limitations of currently used technology in the field of hyperthermia cancer treatment. A novel hyperthermia treatment planning tool and a new head&neck applicator have been developed. The treatment planning tool is optimized for high quality, accurate, realistic simulations of highly detailed m...
Investigations have been carried out to determine the limitations of currently used technology in the field of hyperthermia cancer treatment. A novel hyperthermia treatment planning tool and a new head&neck applicator have been developed. The treatment planning tool is optimized for high quality, accurate, realistic simulations of highly detailed m...
In this study, the radiation emission from mobile phones when used with wireless and wired hands-free kits (HFK) was evaluated to determine the necessity for a dedicated compliance procedure and the extent to which the use of wired and wireless HFK can reduce human exposure. The specific absorption rates (SAR) from wireless HFK were determined expe...
In this paper, for hyperthermia treatment at head and neck region, the optimized patient positions were proposed for different target regions with the proposed applicator. The simulation results showed that the optimization of the patient positions makes more elements have significant contribution. More important, the applicator with the optimized...
INTRODUCTION. European Union Directives 2004/40/EC and 2008/46/EC require a risk assessment of occupational exposure to electromagnetic fields to be carried out. Some MR procedures may involve exposure of staff to electric and/or magnetic fields and/or magnetic flux density values that exceed action values (AVs) defined in the Directives, in which...
A novel indirect measurement technique is developed in which the input impedance of an unknown antenna structure is determined by measuring the change in the measured input impedance of a second probe antenna, while the unknown antenna is loaded at its input by a set of known impedances. The feasibility of the approach is explored using method-of-m...
Investigating occupation exposure in MRI with regard to EU Directive on Physical Agents- Electromagnetic fields
Reverberation chambers have long been used for EMC measurements on equipment; however, it was only recently that they have been developed as a paradigm for animal exposure to radio frequency radiation. This paper describes the system of 21 reverberation chambers developed for the National Toxicology Program of the National Institute of Environmenta...
An overview of CAPANINA, a project funded by the European Commission’s 6th Framework Programme, is presented. The project is developing communications technologies for use with aerial platforms with the aim of integrating users in hard to reach areas and those disadvantaged by geography into the wider broadband network. The article discusses the th...
This paper considers the implementation of multiple element antenna arrays for MIMO wireless systems for use with multiple wireless standards operating at different frequencies. The capacity of such systems for a realistic channel model is considered, and it is shown that it is not generally worthwhile to reduce element spacing below 0.4 wavelength...
This paper compares the performance and complexity of two methods of steering an array of aperture antennas on a high altitude platform for the provision of broadband fixed wireless access using cellular type frequency reuse. The first method is to steer all antennas individually to maintain the boresight at the required cell centre. The paper also...
An overview of CAPANINA, a project funded by the European Commission's 6th Framework Programme is presented. The project is developing communications technologies for use with aerial platforms with the aim of delivering communications to users in hard to reach users and those disadvantaged by geography. The paper discusses the three broad areas of...
The material presented here outlines a study to determine the level of Specific Absorption Rate (SAR) associated with the use of Hands Free Kit's (HFK's) with GSM mobile telephones and to identify the factors that influence these levels. A novel current probe was designed to measure the current profile along the HFK cables. Measurements of the HFK...
The aim of this work was to establish the level of SAR (specific absorption rate) within the head, associated with the use of hands free kits (HFKs) with GSM mobile telephones and to identify the principal factors determining the observed levels of SAR in order to better understand the observed levels. The work was funded as part of the UK governme...
Short range device (SRD) receivers can be prone to blocking due to strong signals in adjacent frequency allocations. In this paper, we report on the typical performance exhibited by representative super-regenerative and superheterodyne SRD receivers and correlate the performance to the circuit architectures used. Based upon the findings of these in...
In a wireless communications network served by a high altitude platform (HAP) the cochannel interference is a function of the antenna beamwidth, angular separation and sidelobe level. At the millimeter wave frequencies proposed for HAPs, an array of aperture type antennas on the platform is a practicable solution for serving the cells. We present a...