Radiofrequency Current Research Articles

The geometry of the ICRF-induced wave–SOL interaction. A multi-machine experimental review in view of the ITER operation

As part of ITPA-Integrated Operational Scenario activities, this contribution reviews recent experimental characterizations of radio-frequency (RF)-induced scrape-off layer (SOL) modifications of various tokamaks worldwide and of the LArge Plasma Device at UCLA. The phenomenology, as observed using a large variety of measurement techniques, is consistent with expectations from RF sheath rectification. Emphasis is then put on the complex three-dimensional (3D) spatial patterns of the RF–SOL interaction, in relation to the magnetic topology and the spatial distribution of RF currents over the metallic structures surrounding the RF wave launchers. Dependence on the local plasma parameters in the antenna vicinity is also briefly addressed. The final part discusses implications for future devices.

Design and engineering challenges of a multi-energy hard x-ray camera for long-pulse profile measurements at WEST tokamak

The WEST tokamak has recently been prepared for long pulse operation with a water-cooled full first wall. Heating is provided by radiofrequency systems, including Lower Hybrid Current Drive (LHCD). The Princeton Plasma Physics Laboratory has developed a multi-energy hard x-ray camera for profile measurements at WEST. The camera is based on a new generation of 2D pixel array detectors that allow the energy threshold to be independently set for each pixel. The diagnostic will provide spatial, temporal and energy resolved measurements of the hard x-ray emission from the full plasma cross-section, investigating several physical quantities such as the electron temperature from continuum emission, the fast electron tail density produced by radiofrequency current drive and runaway electrons, as well as characteristic tungsten x-rays due to beam-target emission at the edge. This work describes the engineering challenges that the WEST long pulse scenario poses for this diagnostic and how the design addresses and solves them. Vacuum, thermal stress and heat transfer calculations are presented and discussed.

Study of RF Stray Currents in ITER Neutral Beam Test Facilities

The operation of SPIDER (Source for the Production of Ions of Deuterium Extracted from Radio-frequency plasma), full-scale prototype of ITER NBI (Neutral Beam Injector) radio-frequency ion source, pointed out deleterious effects caused by stray Radio-Frequency (RF) currents flowing in the electrical equipment not included in the RF power system. MITICA (Megavolt ITER Injector and Concept Advancement), the full-scale prototype of ITER NBI, is characterized by a similar design in terms of layout of the power supplies and connections to the beam source; thus, it is expected to be subject to the RF stray currents problem. SPIDER RF system is composed of four RF generators, four coaxial lines and four RF loads. Each RF generator is rated for operation at 200 kW in the frequency range 0.9 ÷ 1.1 MHz. The power is delivered to the four loads via as many RF coaxial lines, housed inside a multiconductor transmission line. Each load consists of a capacitive matching network and two plasma drivers in series. Due to the presence of stray connections at the generator and beam-source side (e.g., parasitic capacitances), unwanted RF currents can flow through alternative paths and negatively affect the components not intended for transmission of RF power, the output stages of power supplies and several diagnostics installed in the High-Voltage Deck (HVD) and at the beam source. This paper presents the development of a circuital model used to estimate the RF stray currents in SPIDER electrical system; the understanding of this phenomenon and the development of a model with predictive capabilities is fundamental for the assessment of the performance of both SPIDER and MITICA and, in general, of alternative RF system layouts with respect to the stray currents issue.

Assessment of Mechanical Stress Induced by Radiofrequency Currents on Skin Interfaces.

The epidermal-dermal (ED) and dermal-subcutaneous (DS) junctions are the most prominent skin interfaces, which are known to be of primary importance in different dermatological and aesthetic conditions. These interfaces are strongly modified in aging skin, and their effective targeting can lead to improvement of skin appearance in aging and by cellulite. Application of radiofrequency (RF) currents to the skin can selectively produce mechanical stress on these interfaces. Here, we assess the stresses induced by RF currents of different frequencies on EDJ and DSJ and discuss possible applications of the interfacial therapy in aesthetic medicine.

Response of human cancer cells to simultaneous treatment with sorafenib and radiofrequency current.

Due to their alleged analgesic, anti-inflammatory and tissue regenerative effects, capacitive-resistive electrothermal therapy (CRET), which is based on non-invasive exposure to radiofrequency (RF) currents, is often applied to chemotherapeutically treated patients with cancer. Our previous studies have demonstrated that subthermal CRET currents can elicit a number of cell responses, including anti-proliferative effects, in the human liver cancer cell line HepG2. Such effects involve significant changes in the regulation of proteins involved in MAPK signaling pathways, which are also implicated in the cancer cell response to standard anticancer drugs such as sorafenib. This overlap in response pathways may lead to competitive, neutralizing or blocking interactions between the electrical and chemical treatments, thus raising questions on the advisability of CRET treatment for their analgesic, anti-inflammatory or other purposes in patients undergoing chemotherapy. The present study analyzed the effects of simultaneous treatment with sorafenib and 448-kHz, subthermal CRET current on the proliferation and viability of HepG2 cell cultures. Cell viability was assessed through Trypan blue or XTT assays, while flow cytometry was applied for cell cycle and apoptosis analysis. The expression of proteins involved in cell proliferation were assessed by immunoblotting and immunofluorescence. The results revealed no evidence to suggest that the electrical treatment counteracted or neutralized the cellular response to sorafenib at the different conditions evaluated. Furthermore, at the standard pharmacological sorafenib concentration, 5 µM, the combined treatment elicited an anti-proliferative response significantly stronger than that induced by each of the treatments when applied separately in HepG2 cells. These data do not support the hypothesis that CRET exposure may inhibit or diminish the effects of a chemotherapeutic drug used in cancer treatment, and highlights the requirement for further investigation into the cell response to the combined action of electrical and chemical treatments.

Activation of Repair Processes in Patients with Bedsores Using Pulsed Radio-Frequency Currents

Activation of Repair Processes in Patients with Bedsores Using Pulsed Radio-Frequency Currents

Application of an integrated radio-frequency/shim coil technology for signal recovery in fMRI.

Gradient-echo echo-planar imaging (EPI), which is typically used for blood oxygenation level-dependent (BOLD) functional MRI (fMRI), suffers from distortions and signal loss caused by localized B0 inhomogeneities. Such artifacts cannot be effectively corrected for with the low-order spherical harmonic (SH) shim coils available on most scanners. The integrated parallel reception, excitation, and shimming (iPRES) coil technology allows radiofrequency (RF) and direct currents to flow on each coil element, enabling imaging and localized B0 shimming with one coil array. iPRES was previously used to correct for distortions in spin-echo EPI and is further developed here to also recover signal loss in gradient-echo EPI. The cost function in the shim optimization, which typically uses a single term representing the B0 inhomogeneity, was modified to include a second term representing the signal loss, with an adjustable weight to optimize the trade-off between distortion correction and signal recovery. Simulations and experiments were performed to investigate the shimming performance. Slice-optimized shimming with iPRES and the proposed cost function substantially reduced the signal loss in the inferior frontal and temporal brain regions compared to shimming with iPRES and the original cost function or 2nd -order SH shimming with either cost function. In breath-holding fMRI experiments, the ΔB0 and signal loss root-mean-square errors decreased by -34.3% and -56.2%, whereas the EPI signal intensity and number of activated voxels increased by 60.3% and 174.0% in the inferior frontal brain region. iPRES can recover signal loss in gradient-echo EPI, which is expected to improve BOLD fMRI studies in brain regions suffering from signal loss.

In vitro stimulation with radiofrequency currents promotes proliferation and migration in human keratinocytes and fibroblasts

ABSTRACT Capacitive-resistive electric transfer (CRET) therapies have been proposed as strategies for regeneration of cutaneous tissue lesions. Previous studies by our group have shown that intermittent stimulation with 448 kHz CRET currents at subthermal densities promotes in vitro proliferation of human stem cells involved in tissue regeneration. The present study investigates the effects of the in vitro exposure to these radiofrequency (RF) currents on the proliferation and migration of keratinocytes and fibroblasts, the main cell types involved in skin regeneration. The effects of the electric stimulation on cell proliferation and migration were studied through XTT and wound closure assays, respectively. The CRET effects on the expression and location of proteins involved in proliferation and migration were assessed by immunoblot and immunofluorescence. The obtained results reveal that electrostimulation promotes proliferation and/or migration in keratinocytes and fibroblasts. These effects would be mediated by changes observed in the expression and location of intercellular adhesion proteins such as β-catenin and E-cadherin, of proteins involved in cell-to-substrate adhesion such as vinculin, p-FAK and the metalloproteinase MMP-9, and of other proteins that control both processes: MAP kinases p-p38, p-JUNK and p-ERK1/2. These responses could represent a mechanism underlying the promotion of normotrophic wound regeneration induced by CRET. Indeed, electric stimulation would favor completion of granulation tissue formation prior to the closure of the outer tissue layers, thus preventing abnormal wound cicatrization or chronification.

Anterior position of dispersive patch for esophageal protection during atrial fibrillation ablation. A pilot feasibility study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Ablation for atrial fibrillation (AF) carries a significant risk of esophageal injury. Current methods of esophageal protection are invasive, expensive and their cost-effectiveness can be questioned. Standard placement of dispersive patch (DP) at patient’s back exposes esophagus to radio-frequency (RF) current-mediated thermal injury and such complications as esophageal wall ulceration, peri-esophageal injury or life-threatening atrio-esophageal fistula. Redirecting RF current by DP repositioning to anterior chest can theoretically protect oesophagus from thermal injury, however, such an approach has not yet been investigated. Aim To determine feasibility of anterior DP position for treatment of AF using RF catheter ablation (RFCA)-based system. Methods We retrospectively analysed consecutive patients undergoing RFCA-based pulmonary vein isolation (PVI) using multi-electrode PVAC catheter with DP located either in anterior or traditional-posterior position. Two additional patients underwent point-by-point RFCA and mapping of PV ostia with impedance measurements during RFCA performed using anterior and posterior DP positioning. Results 62 patients (25 females, age 60 ± 12 years) underwent PVI using PVAC: 40 patients in posterior and 22 in anterior DP group. There were no major complications during procedures. There was no significant difference in AF recurrence rate between anterior and posterior DP groups during one-year follow up (log rank p = 0.065). In two additional consecutive patients (1 female, age 74 ± 2 years) undergoing point-by-point RFCA a total number of 30 measurements around PV ostia were performed. There was a significant difference between impedance values in anterior vs posterior DP positions (134 ± 7 Ω vs 122 ± 8 Ω, p = 0.0004). Conclusions Anterior position of dispersive electrode for PV isolation using RFCA-based systems is safe, feasible, atraumatic and is not associated with any additional cost. Apart from redirecting RF current away from the esophagus, anterior dispersive patch placement is associated with higher impedance values which can act as an additional protection. Possible prevention of esophageal complications using anterior dispersive patch positioning needs to be determined in prospective studies. Abstract Figure. AF-free survival and impedance

Multi-energy calibration of a PILATUS3 CdTe detector for hard x-ray measurements of magnetically confined fusion plasmas.

A multi-energy hard x-ray pin-hole camera based on the PILATUS3 X 100K-M CdTe detector has been developed at the Princeton Plasma Physics Laboratory for installation on the Tungsten Environment in Steady State Tokamak. This camera will be employed to study thermal plasma features such as electron temperature as well as non-thermal effects such as fast electron tails produced by a lower hybrid radiofrequency current drive and the birth of runaway electrons. The innovative aspect of the system lies in the possibility of setting the threshold energy independently for each of the ∼100k pixels of the detector. This feature allows for the measurement of the x-ray emission in multiple energy ranges with adequate space and time resolution (∼1cm, 2ms) and coarse energy resolution. In this work, the energy dependence of each pixel was calibrated within the range 15 keV-100 keV using a tungsten x-ray tube and emission from a variety of fluorescence targets (from yttrium to uranium). The data corresponding to pairs of Kα emission lines are fit to the characteristic responsivity ("S-curve"), which describes the detector sensitivity across the 64 possible energy threshold values for each pixel; this novel capability is explored by fine-tuning the voltage of a six-bit digital-analog converter after the charge-sensitive amplifier for each of the ∼100k pixels. This work presents the results of the calibration including a statistical analysis. It was found that the achievable energy resolution is mainly limited by the width of the S-curve to 3 keV-10 keV for threshold energies up to 50 keV, and to ≥20 keV for energies above 60 keV.

Optimized phasing conditions to avoid edge mode excitation by ICRH antennas

An ion cyclotron resonance heating (ICRH) antenna system must launch radio frequency (RF) power with a wavenumber spectrum which maximizes the coupling to the plasma. It should also ensure good absorption while minimizing the wave interaction with the plasma edge. Such interactions lead to impurity release, whose effect has been measured far from the antenna location (Klepper et al. 2013; Wukitch et al. 2017; Perkins et al. 2019) and can involve the entire scrape-off layer. In the normal heating scenario, for which the frequency of the waves launched by the antenna is larger than the ion cyclotron frequency of the majority ions $\omega > \omega _{\textrm {ci},\textrm {maj}}$ , release of impurities due to ICRH can be affected by minimizing the low $|k_{\parallel }| < k_0$ power spectrum components of the antenna. Impurity release can be the result of low central absorption of the waves or power transfer from the fast to the slow wave due to the presence of a confluence in the plasma edge. In ASDEX Upgrade (AUG), a reduction of heavy impurity release by ICRH in the plasma was qualitatively well correlated to the parallel electric field and RF currents flowing around the antenna (Bobkov et al. 2017). In this article, we first show a correlation between the reduction in impurity release by ICRH in AUG and the rejection of the low $|k_{\parallel }| < k_0$ region of the antenna power spectrum. We show that the same correlation holds for results obtained in the Alcator C-Mod tokamak. Finally, using this idea, we reproduce ICRH induced impurity release behaviour in a not yet published experiments of JET, and make predictions for ITER and DEMO.

Explaining RF induced current patterns on implantable medical devices during MRI using the transfer matrix.

PurposeIn this work a simulation study is performed to gain insights in the patterns of induced radiofrequency (RF) currents for various implant‐like structures at 1.5 T. The previously introduced transfer matrix (TM) is used to determine why certain current patterns have a tendency to naturally occur. This can benefit current safety assessment techniques and may enable the identification of critical exposure conditions.Theory and MethodsThe induced current on an elongated implant can be determined by multiplication of the incident electric field along the implant with its TM. The eigenmode spectrum of the TMs for various lengths and various types of implants are determined. The eigenvector with the highest eigenvalue describes the incident electric field pattern that induces the highest current which in turn will lead to highest heating. Subsequently, a statistical probability analysis is performed using a wide range of potential incident electric field distributions in a representative human subject model during a 1.5 T MR exam which are determined by means of electromagnetic FDTD simulations. These incident electric field distributions and the resulting induced current patterns are projected onto eigenvectors of the TM to determine which eigenmodes of the implant dominate the current patterns.ResultsThe eigenvectors of the TM of bare and insulated wires resemble sinusoidal harmonics of a string fixed at both ends similar to the natural‐current distribution on thin antennas(1). The currents on implants shorter than 20 cm are generally dominated by the first harmonic (similar to half a sine wave). This is firstly because for these implant lengths (relative to the RF wavelength), the first eigenvalue is more than three times bigger than the second showing the ability of an implant to accommodate one eigenmode better than another. Secondly, the incident electric fields have a high likelihood (≳95,7%) to project predominantly on this first eigenmode.ConclusionThe eigenmode spectrum of the TM of an implant provides insight into the expected shape of induced current distributions and worst‐case exposure conditions. For short implants, the first eigenvector is dominant. In addition, realistic incident electric field distributions project more heavily on this eigenvector. Both effects together cause significant currents to always resemble the dominant eigenmode of the TM for short implants at 1.5 T.

Direct Imaging of High‐Frequency Multimode Spin Wave Propagation in Cobalt‐Iron Waveguides Using X‐Ray Microscopy beyond 10 GHz

Not only in fundamental wave physics but also in technical areas such as radar and communication systems, high‐frequency magnonics is increasingly attracting attention. Here, time‐resolved scanning transmission X‐ray microscopy is used to directly image high‐frequency spin wave propagation in cobalt‐iron waveguides at excitation frequencies above 10 GHz. In addition, an excitation technique is presented, which allows for versatile pump–probe experiments with radio frequency currents up to 30 GHz. With this approach, a global sinusoidal magnetic field excitation is applied to induce spin waves from the waveguide edges. Amplitude, relative phase, and k‐space information as a function of excitation frequencies and static external fields are observed, matching the theoretical predictions for confined waveguide structures. In doing so, the foundation for high‐frequency multimode spin wave excitation and propagation at the nanoscale is laid, which can be a prospective path in radar and communication systems.

RADIOFREQUENCY AS PAIN INTERVENTIONAL THERAPY IN NEUROLOGY

Radiofrequency (RF) intervention uses high frequency alternating current (AC) to inhibit and alter nociceptive pathway in various locations. Radiofrequency is divided into Continuous RF (CRF) and Pulsed RF (PRF). Continuous RF is a process in which the RF current is used to produce thermal lesions on the target nerve that will result in resistance to the afferent nociceptive pathway. PRF is a process whereby short bursts of RF are discharged toward a neural target that will produce a signal for lowering pain. PRF is a therapy of neural tissue with small neurodestructive possibility and is an alternative technique for continuing RF. RF therapy is a minimally invasive procedure that has been used for about three decades to treat various chronic pain syndromes such as trigeminal neuralgia, post herpes neuralgia, lower back pain (LBP), and complex regional pain syndromes or sympathetic reflex dystrophy. The mechanism action of the PRF involves cellular structure damage, neuronal activation, altered gene expression, a global continuation of evoked synaptic activity in pain fibers through centrals and changes in synaptic strength and long-term potentiation. PRF with its various characteristics has a better outcome than conventional RF.

Modulated Electro-Hyperthermia-Induced Tumor Damage Mechanisms Revealed in Cancer Models.

The benefits of high-fever range hyperthermia have been utilized in medicine from the Ancient Greek culture to the present day. Amplitude-modulated electro-hyperthermia, induced by a 13.56 MHz radiofrequency current (mEHT, or Oncothermia), has been an emerging means of delivering loco-regional clinical hyperthermia as a complementary of radiation-, chemo-, and molecular targeted oncotherapy. This unique treatment exploits the metabolic shift in cancer, resulting in elevated oxidative glycolysis (Warburg effect), ion concentration, and electric conductivity. These promote the enrichment of electric fields and induce heat (controlled at 42 °C), as well as ion fluxes and disequilibrium through tumor cell membrane channels. By now, accumulating preclinical studies using in vitro and in vivo models of different cancer types have revealed details of the mechanism and molecular background of the oncoreductive effects of mEHT monotherapy. These include the induction of DNA double-strand breaks, irreversible heath and cell stress, and programmed cells death; the upregulation of molecular chaperones and damage (DAMP) signaling, which may contribute to a secondary immunogenic tumor cell death. In combination therapies, mEHT proved to be a good chemosensitizer through increasing drug uptake and tumor reductive effects, as well as a good radiosensitizer by downregulating hypoxia-related target genes. Recently, immune stimulation or intratumoral antigen-presenting dendritic cell injection have been able to extend the impact of local mEHT into a systemic “abscopal” effect. The complex network of pathways emerging from the published mEHT experiments has not been overviewed and arranged yet into a framework to reveal links between the pieces of the “puzzle”. In this paper, we review the mEHT-related damage mechanisms published in tumor models, which may allow some geno-/phenotype treatment efficiency correlations to be exploited both in further research and for more rational clinical treatment planning when mEHT is involved in combination therapies.

Low-Frequency Nonresonant Rectification in Spin Diodes

Spin-diodes are usually resonant in nature (GHz frequency) and tuneable by magnetic field and bias current with performances, in terms of sensitivity and minimum detectable power, overcoming the semiconductor counterpart, i.e. Schottky diodes. Recently, spin diodes characterized by a low frequency detection (MHz frequency) have been proposed. Here, we show a strategy to design low frequency detectors based on magnetic tunnel junctions having the interfacial perpendicular anisotropy of the same order of the demagnetizing field out-of-plane component. Micromagnetic calculations show that to reach this detection regime a threshold input power has to be overcome and the phase shift between the oscillation magnetoresistive signal and the input radiofrequency current plays the key role in determining the value of the rectification voltage.

Impedance, power, and current in radiofrequency ablation: Insights from technical, ex vivo, and clinical studies.

Radiofrequency (RF) power is routinely considered during RF application. In contrast, impedance has been relatively poorly studied, despite also influencing RF lesion creation. The aim of this study was to examine the influence of electric impedance on RF lesion characteristics and on clinical RF ablation parameters. In the first part of the study, power and impedance were systematically varied and the resulting current was calculated using custom-made software. In the second part of the study, ablation lesions (n = 40) were analyzed in a porcine ex vivo model. RF applications were delivered in cardiac muscle preparations with systematically varied values of electric impedance using a contact force ablation catheter. In the third part of the study, n = 3378 clinical RF applications were analyzed, power, impedance, and current data were exported and correlated with clinical patient data. 20 ± 3 W/80 Ω, 30 ± 3 W/120 Ω, 40 ± 3 W/160 Ω, and 50 ± 3 W/200 Ω RF applications resulted in 498 ± 40, 499 ± 26, 500 ± 20, and 500 ± 16 mA RF current, which were not significantly different (p = .32). Ablation lesions were significantly different in depth and diameter when applied with the same power but different impedances (p < .01); lesion sizes decreased when increasing impedance. In clinical data, a large range of delivered current (e.g., 39-40 W: 530-754 mA) was measured, due to variations in impedance. RF lesion creation is determined by current rather than by power. During clinical RF ablation procedures, impedance significantly influences current delivery and varies considerably between patients. Impedance and current are clinically relevant parameters that should be considered during RF ablation.

Radiofrequency Thoracic Sympathectomy for Sympathetically Maintained Chronic Post-Mastectomy Pain, a Preliminary Report: 6-Month Results.

Evaluation of the analgesic efficacy of radiofrequency thoracic sympathectomy for sympathetically maintained post-mastectomy pain syndrome (PMPS). Patients with PMPS randomized to Group TS (n=33) received radiofrequency thoracic sympathectomy, and those randomized to Group Sham (n=33) received no radiofrequency current. Postoperative pain treatment consisted of duloxetine, pregabalin, and tramadol for both groups. The outcome variables were the proportion of patients who showed >50% reduction in their VAS pain score, the pain intensity measured by VAS score, and the global perceived effect (GPE) evaluated during the 6-month follow-up period. A significantly higher proportion of patients experienced >50% reduction in pain in Group TS (Group TS 25/30 [83.3%] vs. Group Sham 18/31 [58%], P=0.032); the proportion of patients who experienced >50% reduction in their pain without analgesics was significantly higher in Group TS (Group TS 10/25 [40%] vs. Group Sham 0/18 [0%], P=0.001). Furthermore, the proportion of patients treated with tramadol+duloxetine+pregabalin who experienced >50% reduction in their pain was significantly lower in Group TS (Group TS 0/25 [0%] vs. Group Sham 13/18 [75%], P=0.001). The VAS pain score was significantly lower in Group TS at 2weeks and at 1, 2, 3, and 6 months following the procedure. The GPE was significantly higher in Group TS (Group TS median GPE [interquartile range]) 7 [5, 7] vs. Group Sham median GPE [interquartile range]) 5 [4, 6]) P<0.001). Radiofrequency thoracic sympathectomy for sympathetically maintained PMPS decreased VAS pain scores and reduced the need for anti-neuropathic drugs, particularly opioid medications, and provided better patient satisfaction.

Measurement and modeling of the radio frequency sheath impedance in a large magnetized plasma

The DC and radio frequency (RF) properties of RF driven sheaths were studied in the Large Plasma Device (LAPD) at the University of California, Los Angeles. The experiments diagnosed RF sheaths on field lines connected to a grounded plate at one end and an ion cyclotron range of frequencies antenna at the other end. The experimental setup permitted measurement of the RF sheath impedance at the plate as a function of DC sheath voltage, with the latter controlled by varying the RF current applied to the antenna. The DC–voltage characteristics of these sheaths and the RF sheath impedance measurements were compared with modeling. Hot electrons, present in the LAPD plasma, were inferred to contribute significantly to both the DC and RF currents and hence the RF impedance. It was postulated that at very low power, hot electrons could not access the region of the plasma subject to RF waves resulting in an increased RF impedance. Within some experimental limitations and significant assumptions, an RF sheath impedance model was verified by the experimental data.

Continuous But Not Pulsed Radiofrequency Current Generated by NeuroTherm NT500 Impairs Mitochondrial Membrane Potential in Human Monocytic Cells THP-1.

BackgroundThe application of pulsed radiofrequency (PRF) current to peripheral nerves with conditions related to neuropathic pain is considered to be clinically safe, while it has been reported that the destruction of mitochondria after PRF application was observed by electron microscopy. If it occurs reproducibly, PRF applied to peripheral nerves should provoke neurolysis because the impairment of mitochondria is known as the primary cause of apoptosis.MethodsHuman monocytic cells THP-1 loaded with 100 nM tetramethylrhodamine methyl ester (TMRM), a fluorescent dye that proves the mitochondrial membrane potential (MMP), were exposed to the electric field of continuous radiofrequency (CRF) or PRF current. The TMRM-related fluorescence from THP-1 cells was measured by flow cytometry.ResultsThe exposure of THP-1 cells to a PRF electric field generated by NeuroTherm NT500 for 15 min with maximum power did not decrease MMP in these cells, nor did it cause the induction of apoptosis. By contrast, the application of CRF current at 70 °C for 3 min significantly decreased MMP and induced apoptosis within 10 min after CRF application.ConclusionWe conclude from these findings that PRF application does not provoke mitochondrial injury in various types of mammalian cells because the size and the subcellular structure of the plasma membrane or mitochondria are similar among those. However, the present results cannot address the effect of PRF current on organic structure around the nervous system. Further study is required to solve the question of whether PRF current causes neurolysis or not.