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1.
Sensors (Basel) ; 23(9)2023 May 05.
Article in English | MEDLINE | ID: mdl-37177718

ABSTRACT

While hyperthermia has been shown to induce a variety of cytotoxic and sensitizing effects on cancer tissues, the thermal dose-effect relationship is still not well quantified, and it is still unclear how it can be optimally combined with other treatment modalities. Additionally, it is speculated that different methods of applying hyperthermia, such as water bath heating or electromagnetic energy, may have an effect on the resulting biological mechanisms involved in cell death or in sensitizing tumor cells to other oncological treatments. In order to further quantify and characterize hyperthermia treatments on a cellular level, in vitro experiments shifted towards the use of 3D cell spheroids. These are in fact considered a more representative model of the cell environment when compared to 2D cell cultures. In order to perform radiofrequency (RF)-induced heating in vitro, we have recently developed a dedicated electromagnetic field applicator. In this study, using this applicator, we designed and validated an experimental setup which can heat 3D cell spheroids in a conical polypropylene vial, thus providing a reliable instrument for investigating hyperthermia effects at the cellular scale.


Subject(s)
Hyperthermia, Induced , Neoplasms , Humans , Hyperthermia, Induced/methods , Heating , Neoplasms/therapy , Hot Temperature , Radio Waves
2.
Bioelectromagnetics ; 44(3-4): 71-76, 2023 Apr.
Article in English | MEDLINE | ID: mdl-37002551

ABSTRACT

Power density and duty factor values were measured around smart utility meters operating at 868 MHz under laboratory-controlled conditions. The maximum 6-min averaged exposure recorded was 0.1 mWm-2 , which is less than 0.0024% of the corresponding 1998 ICNIRP general public reference level. Duty factors measured were less than 2.8%. This study found that the exposure contribution from Zigbee smart meter devices operating at 868 MHz is generally lower than, if not similar to, those operating at 2.4 GHz. © 2023 Crown copyright. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.


Subject(s)
Electromagnetic Fields , Radio Waves , Environmental Exposure
3.
Bioelectromagnetics ; 44(3-4): 77-89, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36999566

ABSTRACT

The increasing use of nonionizing radiofrequency electromagnetic fields (RF-EMFs) in a wide range of technologies necessitates studies to further understanding of biological effects from exposures to such forms of electromagnetic fields. While previous studies have described mechanisms for cellular changes occurring following exposure to low-intensity RF-EMFs, the role of molecular epigenetics has not been thoroughly investigated. Specifically unresolved is the effect of RF-EMFs on deoxyribonucleic acid (DNA) methylation, which is a powerful epigenetic process, used by cells to regulate gene expression. DNA methylation is dynamic and can be rapidly triggered in response to external stimuli such as exposure to RF-EMFs. In the present study, we performed a global analysis of DNA methylation patterns in human keratinocytes exposed to 900 MHz RF-EMFs for 1 h at a low dose rate (estimated mean specific absorption rate (SAR) < 10 mW/kg). We used a custom system to allow stable exposure of cell cultures to RF-EMFs under biologically relevant conditions (37 °C, 5% CO2 , 95% humidity). We performed whole genome bisulfite sequencing directly following RF-EMF exposure to examine the immediate changes in DNA methylation patterns and identify early differentially methylated genes in RF-EMF-exposed keratinocytes. By correlating global gene expression to whole genome bisulfite sequencing, we identified six common targets that were both differentially methylated and differentially expressed in response to RF-EMF exposure. The results highlight a potential epigenetic role in the cellular response to RF-EMFs. Particularly, the six identified targets may potentially be developed as epigenetic biomarkers for immediate responses to RF-EMF exposure. Bioelectromagnetics. 1-13, © 2023 Bioelectromagnetics Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.


Subject(s)
DNA Methylation , Electromagnetic Fields , Humans , Electromagnetic Fields/adverse effects , Keratinocytes , Radio Waves/adverse effects
4.
Bioelectromagnetics ; 44(1-2): 17-25, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36786436

ABSTRACT

Medical Physics Department (Medical School, University of Thessaly) participated in a Greek National EMF research program (EDBM34) with the scope to measure and evaluate radiofrequency (RF) exposure (27-3000 MHz) in areas of sensitive land use. A thousand (1000) measurements were carried out at two "metropolitan locations" (Athens and Thessaloniki: 624 points) and several rest urban/rural locations (376 points). SRM 3006 spectrum analyzer manufactured by Narda Safety Test Solutions was used. The broadband mean electric field in metropolitan areas was 0.41 V/m, while in the rest of Greece was 0.36 V/m. In metropolitan areas, the predominant RF source was the TV and Radio FM signals (36.2% mean contribution to the total RF exposure level). In the rest areas, the predominant source was the systems of the meteorological and military/defensive service (31.1%). The mobile sector contributed 14.9% in metropolitan areas versus 12.2% in the rest of Greece. The predominant mobile source was 900 MHz in both cases (4.5% in metropolitan areas vs. 3.3% in the rest of Greece). The total exposure from all RF sources complied with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) 2020 safety guidelines [ICNIRP, 2020]. The maximum exposure level was 0.129% of the limit for the metropolitan areas vs. 0.110% for the rest of Greece. Nonremarkable differences between metropolitan areas' exposure and the rest of Greece. In most cases, new 5 G antennas will be added to the existing base stations. Thus, the total exposure may be increased, leading to higher safety distances. © 2023 Bioelectromagnetics Society.


Subject(s)
Cell Phone , Electromagnetic Fields , Greece , Electromagnetic Fields/adverse effects , Environmental Exposure , Radio Waves/adverse effects , Electricity
5.
IEEE Rev Biomed Eng ; 16: 357-370, 2023.
Article in English | MEDLINE | ID: mdl-33983886

ABSTRACT

Modern Active Medical Implantable Devices require communications to transmit information to the outside world or other implantable sub-systems. This can include physiological data, diagnostics, and parameters to optimise the therapeutic protocol. The available options are to use optical, radiofrequency, or ultrasonic communications. However, in all cases, transmission becomes more difficult with deeper transmission through tissue. Challenges include absorption and scattering by tissue, and the need to ensure there are no undesirable heating effects. As such, this paper aims to review research progress in using ultrasound as an alternative for deep tissue communications. We provide an empirical review of the technology and communication protocols that different groups have used, as well as comparing the implications in terms of penetration depth, implant size, and data rate. We conclude that this technique has promise for deeper implants and for intrabody communications between implantable devices (intrabody networks).


Subject(s)
Prostheses and Implants , Wireless Technology , Humans , Ultrasonography , Radio Waves , Technology
6.
Bioelectromagnetics ; 43(7): 404-412, 2022 Oct.
Article in English | MEDLINE | ID: mdl-36335604

ABSTRACT

This study investigates the absorption of the induced E-field in homogeneous biological tissue exposed to highly localized field sources in proximity of the body, such as the charged tips of antennas, where E-field coupling dominates. These conditions are relevant for compliance testing of modern mobile phones where exposure is evaluated at small separation between radiators and the body. We derive an approximation that characterizes the decay of the induced E-field in the tissue as a function of distance. The absorption is quantified in terms of the local specific absorption rate (SAR) at the tissue surface as a function of the charge at the antenna tip. The approximation is based on the analytical evaluation of the E-fields of a charged disk under quasi-static conditions. We validate this approximation using full-wave simulations of dipoles. We demonstrate that the coupling mechanism of the E-field is dominated by the perpendicular field component and that wave propagation need not be considered for the characterization of the exposure. The surface SAR decreases approximately with the fourth power of the distance and with the square of the ratio of the permittivities of the tissue and free-space. The approximation predicts the induced maximum E-field with an accuracy of better than 1.5 dB. © 2022 Bioelectromagnetics Society.


Subject(s)
Cell Phone , Electromagnetic Fields , Radio Waves
7.
J Food Sci ; 87(9): 4068-4081, 2022 Sep.
Article in English | MEDLINE | ID: mdl-35975880

ABSTRACT

In this study, drying of grated potato in a hot air-assisted radio frequency system (HA-RF) and the associated effects on the final potato flour quality were studied. The drying behavior of the grated potatoes at different electrode distances (70-90 mm) and sample thickness (2-4 cm) was investigated. The safe drying (without burning tendency) of the maximum amount of sample (1000 g) in a reasonable drying time was carried out at 80 mm of electrode gap and 4 cm of sample thickness. HA-RF drying kinetics were studied and compared with hot air (HA) and radio frequency (RF) (without hot air) drying methods. HA-RF drying increased drying rate and shortened drying time by about 58% and 70% compared to HA and RF drying, respectively. The properties of the final potato flour obtained after HA-RF drying were also compared with those produced by RF, HA, and freeze drying. The flour obtained by HA-RF was superior to RF and HA dried samples with better retention of cellular microstructure and color. The drying method significantly affected the functional properties, thermal characteristics, pasting properties, and other characteristics of potato flours. PRACTICAL APPLICATION: HA-RF as an alternative drying technology was used for the first time to produce potato flour. The functional, thermal, and structural properties of the HA-RF dried product were compared with those dried by HA, RF, and freeze drying. The results of this study ensured very useful information for the use of potato flour obtained by different drying methods in the development of products with specific functional and rheological properties.


Subject(s)
Solanum tuberosum , Desiccation/methods , Flour/analysis , Hot Temperature , Radio Waves , Solanum tuberosum/chemistry
8.
Sensors (Basel) ; 22(14)2022 Jul 08.
Article in English | MEDLINE | ID: mdl-35890812

ABSTRACT

In recent years, the usage of radio frequency magnetic fields for biomedical applications has increased exponentially. Several diagnostic and therapeutic methodologies exploit this physical entity such as, for instance, magnetic resonance imaging, hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation. Within this framework, the magnetic field focusing and shaping, at different depths inside the tissue, emerges as one of the most important challenges from a technological point of view, since it is highly desirable for improving the effectiveness of clinical methodologies. In this review paper, we will first report some of the biomedical practices employing radio frequency magnetic fields, that appear most promising in clinical settings, explaining the underneath physical principles and operative procedures. Specifically, we direct the interest toward hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation, together with a brief mention of magnetic resonance imaging. Additionally, we deeply review the technological solutions that have appeared so far in the literature to shape and control the radio frequency magnetic field distribution within biological tissues, highlighting human applications. In particular, volume and surface coils, together with the recent raise of metamaterials and metasurfaces will be reported. The present review manuscript can be useful to fill the actual gap in the literature and to serve as a guide for the physicians and engineers working in these fields.


Subject(s)
Human Body , Hyperthermia, Induced , Humans , Hyperthermia, Induced/methods , Magnetic Fields , Magnetic Resonance Imaging/methods , Radio Waves
9.
Sensors (Basel) ; 22(14)2022 Jul 21.
Article in English | MEDLINE | ID: mdl-35891136

ABSTRACT

This paper presents a radio frequency (RF) triple pole triple throw 3P3T cross antenna switch for cellular mobile devices. The negative biasing scheme was applied to improve the power-handling capability and linearity of the switch by increasing the maximum tolerable voltage drop across the drain and source and reverse biasing the parasitic junction diodes. To avoid signal reflection through the antenna in off-state, all the antenna ports were equipped with 50-ohm termination to provide the pull-down path. Considering the simultaneous operation of antenna ports in different switch cases, the presented T-type pull-down path demonstrated improvement of isolation by over 15 dB. Using stacked switches, the 3P3T handled the input power level of over 35 dBm. The chip was manufactured in 65 nm complementary metal oxide semiconductor (CMOS) silicon on insulator (SOI) technology with a die size of 790 × 730 µm. The proposed structure achieved insertion loss, isolation, and voltage standing wave ratio (VSWR) of less than -0.9 dB, -40 dB, and 1.6, respectively, when the input signal was 3.8 GHz. The measured results prove the implemented switch shows the second and third harmonic distortion performances of less than -60 dBm when the input power level and frequency are 25 dBm and 3.8 GHz, respectively.


Subject(s)
Radio Waves , Semiconductors , Computers, Handheld , Silicon
10.
Nano Lett ; 22(14): 5944-5953, 2022 07 27.
Article in English | MEDLINE | ID: mdl-35816764

ABSTRACT

A combined treatment using medication and electrostimulation increases its effectiveness in comparison with one treatment alone. However, the organic integration of two strategies in one miniaturized system for practical usage has seldom been reported. This article reports an implantable electronic medicine based on bioresorbable microneedle devices that is activated wirelessly for electrostimulation and sustainable delivery of anti-inflammatory drugs. The electronic medicine is composed of a radio frequency wireless power transmission system and a drug-loaded microneedle structure, all fabricated with bioresorbable materials. In a rat skeletal muscle injury model, periodic electrostimulation regulates cell behaviors and tissue regeneration while the anti-inflammatory drugs prevent inflammation, which ultimately enhance the skeletal muscle regeneration. Finally, the electronic medicine is fully bioresorbable, excluding the second surgery for device removal.


Subject(s)
Absorbable Implants , Electric Stimulation Therapy , Animals , Drug Delivery Systems , Electronics, Medical , Radio Waves , Rats , Wireless Technology
11.
Sensors (Basel) ; 22(10)2022 May 10.
Article in English | MEDLINE | ID: mdl-35632018

ABSTRACT

The evaluation of the biological effects of therapeutic hyperthermia in oncology and the precise quantification of thermal dose, when heating is coupled with radiotherapy or chemotherapy, are active fields of research. The reliable measurement of hyperthermia effects on cells and tissues requires a strong control of the delivered power and of the induced temperature rise. To this aim, we have developed a radiofrequency (RF) electromagnetic applicator operating at 434 MHz, specifically engineered for in vitro tests on 3D cell cultures. The applicator has been designed with the aid of an extensive modelling analysis, which combines electromagnetic and thermal simulations. The heating performance of the built prototype has been validated by means of temperature measurements carried out on tissue-mimicking phantoms and aimed at monitoring both spatial and temporal temperature variations. The experimental results demonstrate the capability of the RF applicator to produce a well-focused heating, with the possibility of modulating the duration of the heating transient and controlling the temperature rise in a specific target region, by simply tuning the effectively supplied power.


Subject(s)
Hyperthermia, Induced , Radio Waves , Hyperthermia, Induced/methods , In Vitro Techniques , Phantoms, Imaging , Temperature
12.
Bioelectromagnetics ; 43(4): 218-224, 2022 May.
Article in English | MEDLINE | ID: mdl-35476263

ABSTRACT

Radiofrequency radiation (RFR) was classified as a "possible" human carcinogen in 2011, which caused great public concern. A carcinogenicity study by the National Toxicology Program (NTP) found Code Division Multiple Access-and Global System for Mobile Communications-modulated mobile phone RFR to be carcinogenic to the brain and heart of male rats. As part of an investigation of mobile phone carcinogenesis, and to verify the NTP study results, a 5-year collaborative animal project was started in Korea and Japan in 2019. An international animal study of this type has two prerequisites: use of the same study protocol and the same RF-exposure system. This article discusses our experience in the design of this global study on radiofrequency electromagnetic fields (RF-EMFs).© 2022 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.


Subject(s)
Cell Phone , Radio Waves , Animals , Brain , Carcinogenesis , Electromagnetic Fields , Male , Rats
13.
Bioelectromagnetics ; 43(4): 257-267, 2022 May.
Article in English | MEDLINE | ID: mdl-35485721

ABSTRACT

This study aims to analyze in real-time the potential modifications induced by low-level continuous-wave and Global System for Mobile Communications radiofrequency (RF) exposure at 1.8 GHz on brain activation in anesthetized mice. A specific in vivo experimental setup consisting of a dipole antenna for the local exposure of the brain was fully characterized. A unique neuroimaging technique based on a functional ultrasound (fUS) probe was used to observe the areas of mice brain activation simultaneously to the RF exposure with unprecedented spatial and temporal resolution (~100 µm, 1 ms) following manual whisker stimulation using a brush. Numerical and experimental dosimetry was carried out to characterize the exposure and to guarantee the validity of the biological results. Our results show that the fUS probe can be efficiently used during in vivo exposure without interference with the dipole. In addition, we conclude that exposure to brain-averaged specific absorption rate levels of 2 and 6 W/kg does not introduce significant changes in the time course of the evoked fUS response in the left barrel field cortex. The proposed technique represents a valuable instrument for providing new insights into the possible effects induced on brain activation under RF exposure. For the first time, brain activity under mobile phone exposure was evaluated in vivo with fUS imaging, paving the way for more realistic exposure configurations, i.e. awake mice and new signals such as the 5 G networks. © 2022 Bioelectromagnetics Society.


Subject(s)
Cell Phone , Radio Waves , Animals , Brain/diagnostic imaging , Mice , Radiometry
14.
Urologiia ; (2): 54-58, 2022 May.
Article in Russian | MEDLINE | ID: mdl-35485814

ABSTRACT

AIM: To evaluate the efficiency of radio wave electrotherapy (448 kHz) for the treatment of patients with organic erectile dysfunction (ED). MATERIALS AND METHODS: A prospective, randomized, blind, sham- controlled clinical trial was carried out. Inclusion criteria were as following: 1) patients with 5 to 20 points on the IIEF-5 score; 2) patients with proven organic erectile dysfunction lasting at least 6 months; 3) patients with penile arterial insufficiency and/or venous insufficiency, confirmed by doppler study of penile vessels with pharmacological stimulation (peak systolic velocity (PSV) <25 cm/s, end-diastolic blood flow velocity (DPV) >5 cm/s, resistance index (IR) < 0.8). The participants were randomized into two groups (experimental and control) in a 1:1 ratio. The full treatment course lasted 9 weeks. Patients underwent an assessment of erectile function based on questionnaires (IIEF-5, SEP, Schramek), as well as Doppler ultrasound of the cavernous arteries before inclusion in the study as well as a after treatment. RESULTS: The study included 61 men (experimental group [n=31], control group [n=30]. There was a significant difference in the IIEF-5 scores after treatment between the experimental group and the control group (19.5+/-3.2 vs. 15.1+/-5.4, p=0.017, respectively). Significant differences were also noted in mean total score of the SEP questionnaire: an increase to 3.6+/-1.0 in the treatment group compared to 2.4+/-1.1 in the control group (p=0.004). The results of the Schramek questionnaire also demonstrated a significant increase in the mean score in the experimental group compared to the control group: 4.2+/-0.6 vs. 3.2+/-1.0 (p=0.011). The response time to the drug and the detumescence time also significantly differed between the two groups: 11.9+/-4.0 min vs. 15.5+/-4.1 min, p=0.001 and 126.6+/-60.7 min vs. 66.2+/-40.9, p<0.001, respectively. Neither complications nor any adverse events were recorded during treatment or after its completion. CONCLUSIONS: Radio wave electrotherapy with a radiofrequency of 448 kHz can improve the IIEF-5, SEP and Schramek scores, as well as the indicators of ultrasound Doppler ultrasonography in patients with organic ED. To assess the feasibility of this method in patients with organic ED of different stages, further studies are needed.


Subject(s)
Electric Stimulation Therapy , Erectile Dysfunction , Female , Humans , Male , Penile Erection , Prospective Studies , Radio Waves
15.
Int J Mol Sci ; 23(2)2022 Jan 08.
Article in English | MEDLINE | ID: mdl-35054844

ABSTRACT

It remains controversial whether exposure to environmental radiofrequency signals (RF) impacts cell status or response to cellular stress such as apoptosis or autophagy. We used two label-free techniques, cellular impedancemetry and Digital Holographic Microscopy (DHM), to assess the overall cellular response during RF exposure alone, or during co-exposure to RF and chemical treatments known to induce either apoptosis or autophagy. Two human cell lines (SH-SY5Y and HCT116) and two cultures of primary rat cortex cells (astrocytes and co-culture of neurons and glial cells) were exposed to RF using an 1800 MHz carrier wave modulated with various environmental signals (GSM: Global System for Mobile Communications, 2G signal), UMTS (Universal Mobile Telecommunications System, 3G signal), LTE (Long-Term Evolution, 4G signal, and Wi-Fi) or unmodulated RF (continuous wave, CW). The specific absorption rates (S.A.R.) used were 1.5 and 6 W/kg during DHM experiments and ranged from 5 to 24 W/kg during the recording of cellular impedance. Cells were continuously exposed for three to five consecutive days while the temporal phenotypic signature of cells behavior was recorded at constant temperature. Statistical analysis of the results does not indicate that RF-EMF exposure impacted the global behavior of healthy, apoptotic, or autophagic cells, even at S.A.R. levels higher than the guidelines, provided that the temperature was kept constant.


Subject(s)
Apoptosis , Autophagy , Radio Waves , Staining and Labeling , Arsenic Trioxide/pharmacology , Astrocytes/drug effects , Astrocytes/pathology , Autophagy/drug effects , Cell Line, Tumor , Culture Media, Serum-Free , Electric Impedance , Holography , Humans , Neurons/drug effects , Neurons/pathology , Time Factors
16.
Int J Food Microbiol ; 363: 109500, 2022 Feb 16.
Article in English | MEDLINE | ID: mdl-34952411

ABSTRACT

Microbial contamination is a persistent problem for grain industry. Many studies have shown that radio frequency (RF) heating can effectively reduce pathogens populations in low moisture foods, but there is a lack on the efficacy to decontaminate natural microbiome. The main objectives of this study were to investigate the effects of different RF heating conditions on natural microbial populations and physicochemical properties of buckwheat. In this study, 30 buckwheat samples collected from 10 different Provinces in China were analyzed for their microbial loads, and the samples with the highest microbial populations were used for further study to select the suitable RF heating conditions. The results showed that microbial loads in tested buckwheat kernels were in the range of 3.4-6.2 log CFU/g. Samples from Shanxi (SX-3) had significantly higher microbial counts than other samples. The selected four temperature-time combinations: 75 °C-20 min, 80 °C-10 min, 85 °C-5 min, and 90 °C-0 min of RF heating could reduce microbial counts to <3.0 log CFU/g in buckwheat kernels at 16.5% w.b. moisture content. Furthermore, the reduction populations of the inoculated pathogens (Salmonella Typhimurium, Escherichia coli, Cronobacter sakazakii, and Bacillus cereus) reached 4.0 log CFU/g under the above conditions, and almost 5.0 log CFU/g especially at high temperature-short holding time combinations (85 °C-5 min and 90 °C-0 min). Besides, physicochemical properties evaluation also showed the insignificant color changes and nutrients loss after RF treatment at 90 °C-0 min. Therefore, the RF heating at 90 °C-0 min holds greater potential than the other lower temperature-longer holding time combinations for applications in buckwheat pasteurization.


Subject(s)
Fagopyrum , Heating , Colony Count, Microbial , Food Microbiology , Pasteurization , Radio Waves
17.
Electromagn Biol Med ; 41(1): 1-14, 2022 Jan 02.
Article in English | MEDLINE | ID: mdl-34382485

ABSTRACT

Although the evidence is inconclusive, epidemiological studies strongly suggest that increased exposure to electromagnetic radiation (EMR) increases the risk of brain tumors, parotid gland tumors, and seminoma. The International Agency for Research on Cancer (IARC) has classified mobile phone radiofrequency radiation as possibly carcinogenic to humans (Group 2B). Humans being are inadvertently being exposed to EMR as its prevalence increases, mainly through mobile phones. Radiation exposure is unavoidable in the current context, with mobile phones being an inevitable necessity. Prudent usage of medicinal plants with a long history of mention in traditional and folklore medicine and, more importantly, are safe, inexpensive, and easily acceptable for long-term human use would be an appealing and viable option for mitigating the deleterious effects of EMR. Plants with free radical scavenging, anti-oxidant and immunomodulatory properties are beneficial in maintaining salubrious health. Green tea polyphenols, Ginkgo biloba, lotus seedpod procyanidins, garlic extract, Loranthus longiflorus, Curcuma amada, and Rosmarinus officinalis have all been shown to confer neuroprotective effects in validated experimental models of study. The purpose of this review is to compile for the first time the protective effects of these plants against mobile phone-induced neuronal damage, as well as to highlight the various mechanisms of action that are elicited to invoke the beneficial effects.


Subject(s)
Cell Phone , Plants, Medicinal , Antioxidants , Electromagnetic Fields , Electromagnetic Radiation , Humans , Neurons , Radio Waves
18.
Bioelectromagnetics ; 43(1): 14-24, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34719046

ABSTRACT

Biological effects in the microwave band of the radiofrequency (RF) spectrum are thermally mediated. For acute high-power microwave exposures, these effects will depend on transient time-temperature histories within the tissue. In this article, we summarize the transient temperature response of rats exposed to RF energy emanating from an open-ended rectangular waveguide. These exposures produced specific absorption rates of approximately 36 and 203 W/kg in the whole body and brain, respectively. We then use the experimentally measured thermal data to infer the baseline perfusion rate in the brain and modify a custom thermal modeling tool based upon these findings. Finally, we compare multi-physics simulations of rat brain temperature against empirical measurements in both live and euthanized subjects and find close agreement between model and experimentation. This research revealed that baseline brain perfusion rates in rat subjects could be larger than previously assumed in the RF thermal modeling literature, and plays a significant role in the transient thermal response to high-power microwave exposures. © 2021 Bioelectromagnetics Society.


Subject(s)
Body Temperature , Brain/radiation effects , Radio Waves , Animals , Microwaves/adverse effects , Radio Waves/adverse effects , Rats , Temperature
19.
Annu Int Conf IEEE Eng Med Biol Soc ; 2021: 4159-4162, 2021 11.
Article in English | MEDLINE | ID: mdl-34892141

ABSTRACT

This paper presents a fast method to predict the radiofrequency (RF) induced heating for Sacral Neuromodulation System (SNM) under multi-channel 2 (MC-2) RF field of 3 Tesla (T) magnetic resonance imaging (MRI) system by using the artificial neural network (ANN). The raw computational model for the SNM was based on the transfer function approach. The MC-2 parallel transmission RF field at 3T MRI exposure was considered for 2 independent channels, which have an exposure space of -15 dB to 15 dB magnitude difference and -180 degrees to 170 degrees phase difference. A total number of 535,680 study cases that cover all possible shimming conditions and the corresponding temperature rises are collected from raw calculation data. The ANN was used as the surrogate model to predict the temperature rises against the incident electromagnetic field distributions. 40320 cases were used for training while the rest data sets were used for testing. The ANN can estimate the temperature rises for each human model in a small exposure sampling space. The testing performance of the ANN has a correlation coefficient higher than 0.99 and the mean absolute error was less than 0.12°C. It is demonstrated that the ANN can be used as an efficient tool for quick temperature rise estimation under MRI 3T shimming.


Subject(s)
Electric Stimulation Therapy , Heating , Electromagnetic Fields , Humans , Magnetic Resonance Imaging , Radio Waves
20.
J Bodyw Mov Ther ; 28: 298-310, 2021 10.
Article in English | MEDLINE | ID: mdl-34776156

ABSTRACT

OBJECTIVE: To assess the change in temperature caused by different short wave diathermy (SWD) methods of application in different healthy tissues. DATA SOURCES: The Cochrane Central Register of Controlled Trials, MEDLINE, Science Direct, CINAHL, SciELO, PEDro, ClinicalTrials.gov, Brazilian Registry of Clinical Trials and the World Health Organization ICTRP were searched (1990-April 2020). METHODS: Randomized, quasi-randomized, and single-arm controlled trials assessing temperature change after SWD application in healthy adults were included. Group analysis was done according to SWD mode and where temperature was collected, risk of bias was assessed using the Cochrane tool and the quality of evidence using GRADE. A narrative synthesis was conducted since methodological homogeneity was not sufficient to undertake a meta-analysis. RESULTS: Eleven studies were included, reporting data of 240 subjects. Regarding skin temperature change, the application that increased temperature the most was under the electrode using continuous SWD on coplanar arrangement of capacitive technique (7.9 [1.76] °C), coplanar arrangement also had the slowest temperature decay, and the lowest temperature found was through a low dose application of pulsed SWD (0.34 [0.69] °C). Regarding muscle temperature change, the application that increased temperature the most was using the inductive technique of pulsed SWD (4.58 [0.87] °C), this technique also had the slowest temperature decay, and the lowest temperature found was through ReBound shortwave diathermy (2.31 [0.87] °C). CONCLUSION: SWD efficacy depends on setting choices. This review provides a detailed description of SWD methods of application and a quantitative data set of resulting temperature change.


Subject(s)
Diathermy , Heating , Adult , Humans , Pain Management , Radio Waves , Randomized Controlled Trials as Topic , Skin
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