The exposure of a subject in the far field radiofrequency sources operating 10-900-MHz range has been studied. electromagnetic inside an anatomical heterogeneous model human body computed by using finite-difference time-domain method; corresponding temperature increase evaluated through explicit formulation bio-heat equation. thermal used, which takes into account thermoregulatory system body, validated comparison with experimental data. results show that peak specific absorption rate (SAR)...

In this paper, a complete electromagnetic and thermal analysis has been performed considering the head of subject exposed to various kinds cellular phones available on market, focusing attention important organs like eye lens brain. Attention first posed particular phone model, comparison between absorbed power distribution steady-state temperature increases carried out. The influence different antennas (dipole, monopole, whip, planar inverted F antenna) absorption consequent tissue heating...

In microwave thermal ablation (MTA) therapy, the dielectric properties of target tissue play an important role in determining radiation antenna. this work, ex vivo bovine liver were experimentally characterized as a function temperature during MTA at frequency 2.45 GHz. The obtained data compared with measurements performed end treatment, and considering heating achieved temperature-controlled water bath. Finally, measured used to perform numerical study evaluating effects changes tissue's...

A new coaxial antenna for microwave ablation therapies is proposed. The design includes a miniaturized choke and an arrowhead cap to facilitate insertion into the tissues. Antenna matching shape dimension of area ablated tissue (thermal lesion) obtained in ex vivo conditions are evaluated both numerically experimentally, finding optimal agreement between numerical experimental data. Results show that well matched, it able produce thermal lesion with average length 6.5 cm diameter 4.5 bovine...

Wireless personal communication is a rapidly expanding sector, particularly in the field of cellular mobile phones and wireless local area networks (WLAN's). In an indoor WLAN system, user terminal can find himself close proximity to radiating antenna. It is, therefore, important consider possible health hazards due this type exposure. As most considered adverse effects electromagnetic (EM) fields are thermal nature, with reference eye, paper, authors have evaluated temperature increase...

Microwave thermal ablation (MTA) therapies exploit the local absorption of an electromagnetic field at microwave (MW) frequencies to destroy unhealthy tissue, by way a very high temperature increase (about 60 °C or higher). To develop reliable interventional protocols, numerical tools able correctly foresee obtained in tissue would be useful. In this work, different models dielectric and property changes with were investigated, looking simulated increments size achievable zone ablation....

Purpose: The aim of this study was to characterise changes in tissue volume during image-guided microwave ablation order arrive at a more precise determination the true zone. Materials and methods: effect power (20–80 W) time (1–10 min) on microwave-induced contraction experimentally evaluated various-sized cubes ex vivo liver (10–40 mm ± 2 mm) muscle (20 40 embedded agar phantoms (N = 119). Post-ablation linear volumetric dimensions were measured compared with pre-ablation dimensions....

Purpose: This work focuses on the characterisation of ablated area induced by a microwave thermal ablation (MTA) procedure. An experimental methodology for establishing straightforward correlation between temperature gradient and changes in dielectric properties tissue is presented discussed. Materials methods: Temperature measurements were performed during an procedure ex vivo bovine liver, at different distances from antenna, whereas complex permittivity conducted sagittal sections...

This paper experimentally validates the capability of a microwave prototype device to localize hemorrhages and ischemias within brain as well proposes an innovative calibration technique based on measured data. In reported experiments, 3-D human-like head phantom is considered, where represented either with homogeneous liquid mimicking dielectric properties or ex vivo calf brains. The imaging (MWI) system works at 1 GHz, it realized low-complexity architecture formed by array twenty-four...

Despite the significant number of studies published on measurements complex permittivity biological tissues in last thirty years, implementing a successful measurement program for dielectric can still present challenge researchers. Most problems are not theoretical but methodological or practical nature. In this article, lessons learned from experiences with goal-oriented presented by structuring them into guidelines efficient and useful properties tissues, aimed at addressing gaps...

The aim of this study was to develop a predictive model the shrinkage liver tissues in microwave ablation.Thirty-seven cuboid specimens ex vivo bovine size ranging from 2 cm 8 were heated exploiting different techniques: 1) using oven (2.45 GHz) operated at 420 W, 500 W and 700 for 20 min, achieving complete carbonisation specimens, 2) radiofrequency ablation apparatus (450 kHz) 70 time 6 7.5 min obtaining white coagulation 3) 60 10 min. Measurements specimen dimensions, carbonised...

Thermal ablation treatments are gaining a lot of attention in the clinics thanks to their reduced invasiveness and capability treating non-surgical patients. The effectiveness these impact hospital’s routine would significantly increase if paired with monitoring technique able control evolution treated area real-time. This is particularly relevant microwave thermal ablation, wherein larger tumors shorter time needs proper monitoring. Current diagnostic imaging techniques do not provide...

Thermal properties of ex vivo bovine liver were measured as a function temperature, by heating tissue samples in temperature-controlled oil bath over temperature range from about 21 °C to 113 °C. Results evidenced temperature-dependent non-linear changes the thermal properties, with 100 representing break point: increased up 99 and then decreased above The rate increase appeared dramatic between 90 °C, owing onset vaporisation water contained tissue. In particular, at conductivity reported...

Thermal ablation treatment of cancer is increasingly adopted in the clinical practice, being minimally invasive and highly specific. However, a significant drawback technique lack effective imaging modalities for monitoring changes undergoing thermally treated tissue. In this respect, microwave has been proposed as possible candidate, owing to its portability, low-cost, non-ionizing nature, capability detect dielectric properties tissues induced by temperature. The goal paper provide...

Microwave imaging is emerging as an alternative modality to conventional medical diagnostics technologies. However, its adoption hindered by the intrinsic difficulties faced in solution of underlying inverse scattering problem, namely non-linearity and ill-posedness. In this paper, innovative approach for a reliable automated problem presented, which combines qualitative technique deep learning two-step framework. first step, orthogonality sampling method employed process measurements...

The purpose of this paper is to calculate the specific absorption rate (SAR) distribution in a human head exposed electromagnetic field emitted from handheld cellular phone operating 900 MHz range partially closed environment. environment could be, for example, interior car, condition exposure which largely diffused nowadays. presence reflecting surfaces near modifies current on, and emitting properties of, antenna. Therefore, absorbed power inside different that free space condition....

In this paper, the human exposure to electromagnetic field radiated by a radio base-station antenna operating around 900 MHz in an urban environment has been analyzed. A hybrid ray-tracing/finite-difference time-domain (FDTD) method used evaluate incident and power absorbed exposed subject presence of reflecting walls. The characterized means its radiation pattern, evaluated with FDTD analysis typical panel antenna. Three particular situations for rooftop mounted have considered. all...

A numerically efficient way to evaluate specific absorption rate (SAR) deposition and temperature elevation inside the head of a user cellular phone equipped with dual-band monopole-helix antenna is proposed. The considered operates at both frequencies (900 1800 MHz) employed in global system for mobile communication. results obtained show that, given radiated power, although maximum SAR value as averaged over 1 g brain higher 900 MHz than MHz, increase MHz. However, taking into account that...

A 915-MHz antenna design that produces specific absorption rate distributions with preferential power deposition in tissues surrounding and including the distal end of catheter is described. The features minimal reflected microwave current from flowing up transmission line. This cap-choke consists an annular cap a coaxial choke which matches to minimizes heating cable its performance not affected by depth insertion into tissue. paper provides comparison results obtained computer modeling...

In this paper the propagation of a UWB pulse into layered model human body is studied to characterize absorption and reflection signal due different tissues. Several time behaviours for incident are considered compared with reference feasibility breath heartbeat activity monitoring. Results show that if source placed far from body, coming interface between air skin can be used detect respiratory activity. On contrary, close small posterior lung wall bone, which well distanced in reflections...

To evaluate, characterise and compare the extent of tissue shrinkage induced from three different commercial microwave ablation devices, to elucidate mechanism behind distinctive performances obtained.Microwave (N = 152) was conducted with devices on cubes ex vivo liver (10-40 ± 2 mm/side) embedded in agar phantoms. 50-60 W applied for 1-10 min duration. Pre- post-ablation dimensions samples, as well carbonisation coagulation were measured correlated. ANOVA performed evaluate statistical...

Locoregional hyperthermia is applied to deep-seated tumours in the pelvic region. Two very different heating techniques are often applied: capacitive and radiative heating. In this paper, numerical simulations compare performance of both tumours.Phantom were performed for small (30 × 20 50 cm3) large (45 30 cm3), homogeneous fatless inhomogeneous fat-muscle, tissue-equivalent phantoms with a central or eccentric target Radiative was simulated 70 MHz AMC-4 system at 13.56 MHz. Simulations...