Science.gov

Sample records for 1763mhz radiofrequency radiation

  1. Induction of Hair Growth by Insulin-Like Growth Factor-1 in 1,763 MHz Radiofrequency-Irradiated Hair Follicle Cells

    PubMed Central

    Jo, Seong Jin; Cho, A-Ri; Jeon, Soon-Ik; Choi, Hyung-Do; Kim, Kyu Han; Park, Gun-Sik; Pack, Jeong-Ki; Kwon, Oh Sang; Park, Woong-Yang

    2011-01-01

    Radiofrequency (RF) radiation does not transfer high energy to break the covalent bonds of macromolecules, but these low energy stimuli might be sufficient to induce molecular responses in a specific manner. We monitored the effect of 1,763 MHz RF radiation on cultured human dermal papilla cells (hDPCs) by evaluating changes in the expression of cytokines related to hair growth. The expression of insulin-like growth factor-1 (IGF-1) mRNA in hDPCs was significantly induced upon RF radiation at the specific absorption rate of 10 W/kg, which resulted in increased expression of B-cell chronic lymphocytic leukemia/lymphoma 2 (BCL-2) and cyclin D1 (CCND1) proteins and increased phosphorylation of MAPK1 protein. Exposure to 10 W/kg RF radiation 1 h per day for 7 days significantly enhanced hair shaft elongation in ex vivo hair organ cultures. In RF-exposed follicular matrix keratinocytes in the hair bulb, the expression of Ki-67 was increased, while the signal for terminal deoxynucleotidyl transferase dUTP nick end labeling was reduced. From these results, we suggest that 1,763 MHz RF exposure stimulates hair growth in vitro through the induction of IGF-1 in hDPCs. PMID:22164296

  2. RADIOFREQUENCY RADIATION: ACTIVITIES AND ISSUES

    EPA Science Inventory

    The question of human safety relative to exposure to RF radiation obviously predates the first ANSI guideline established in 1966, but no enforceable Federal standards or guidelines exist for RF radiation exposure; the ANSI guideline which was revised in 1982 is voluntary or advi...

  3. Genetic effects of radiofrequency radiation (RFR)

    SciTech Connect

    Verschaeve, L. . E-mail: luc.verschaeve@vito.be

    2005-09-01

    The possible effects of radiofrequency (RF) exposure on the genetic material of cells are considered very important since damage to the DNA of somatic cells can be linked to cancer development or cell death whereas damage to germ cells can lead to genetic damage in next and subsequent generations. This is why the scientific literature reports many investigations on the subject. According to a number of review papers, the conclusion so far is that there is little evidence that RFR is directly mutagenic and that adverse effects that were reported in some of the papers are predominantly the result of hyperthermia. Yet, some subtle indirect effects on DNA replication and/or transcription of genes under relatively restricted exposure conditions cannot be ruled out. Furthermore, the possibility of combined effects of RFR with environmental carcinogens/mutagens merits further attention. The present paper takes into account more recent investigations but the conclusion remains the same. A majority of studies report no increased (cyto)genetic damage but yet, a considerable number of investigations do. However, many studies were not sufficiently characterized, are therefore difficult to replicate and cannot be compared to others. Experimental protocols were very different from one study to another and investigations from a single laboratory were very often limited in the sample size or number of cells investigated, preventing a robust statistical analysis. Subtle, but significant differences between RFR-exposed and sham-exposed cells cannot be found in such conditions. For the above reasons, it was concluded at a workshop in Loewenstein (November 2002) that further investigations by individual laboratories most probably will not add much to the discussion of radiofrequency radiation (RFR) genotoxicity. Large, well coordinated, international collaborative studies involving participation of several experienced scientists are considered an alternative of uttermost importance

  4. Genetic effects of radiofrequency radiation (RFR).

    PubMed

    Verschaeve, L

    2005-09-01

    The possible effects of radiofrequency (RF) exposure on the genetic material of cells are considered very important since damage to the DNA of somatic cells can be linked to cancer development or cell death whereas damage to germ cells can lead to genetic damage in next and subsequent generations. This is why the scientific literature reports many investigations on the subject. According to a number of review papers, the conclusion so far is that there is little evidence that RFR is directly mutagenic and that adverse effects that were reported in some of the papers are predominantly the result of hyperthermia. Yet, some subtle indirect effects on DNA replication and/or transcription of genes under relatively restricted exposure conditions cannot be ruled out. Furthermore, the possibility of combined effects of RFR with environmental carcinogens/mutagens merits further attention. The present paper takes into account more recent investigations but the conclusion remains the same. A majority of studies report no increased (cyto)genetic damage but yet, a considerable number of investigations do. However, many studies were not sufficiently characterized, are therefore difficult to replicate and cannot be compared to others. Experimental protocols were very different from one study to another and investigations from a single laboratory were very often limited in the sample size or number of cells investigated, preventing a robust statistical analysis. Subtle, but significant differences between RFR-exposed and sham-exposed cells cannot be found in such conditions. For the above reasons, it was concluded at a workshop in Löwenstein (November 2002) that further investigations by individual laboratories most probably will not add much to the discussion of radiofrequency radiation (RFR) genotoxicity. Large, well coordinated, international collaborative studies involving participation of several experienced scientists are considered an alternative of uttermost importance

  5. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Radiofrequency radiation for the heating of food... PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation,...

  6. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Radiofrequency radiation for the heating of food... PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation,...

  7. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Radiofrequency radiation for the heating of food... FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be...

  8. Genetic damage in subjects exposed to radiofrequency radiation.

    PubMed

    Verschaeve, Luc

    2009-01-01

    Despite many research efforts and public debate there is still great concern about the possible adverse effects of radiofrequency (RF) radiation on human health. This is especially due to the enormous increase of wireless mobile telephones and other telecommunication devices throughout the world. The possible genetic effects of mobile phone radiation and other sources of radiofrequencies constitute one of the major points of concern. In the past several review papers were published on laboratory investigations that were devoted to in vitro and in vivo animal (cyto)genetic studies. However, it may be assumed that some of the most important observations are those obtained from studies with individuals that were exposed to relatively high levels of radiofrequency radiation, either as a result of their occupational activity or as frequent users of radiofrequency emitting tools. In this paper the cytogenetic biomonitoring studies of RF-exposed humans are reviewed. A majority of these studies do show that RF-exposed individuals have increased frequencies of genetic damage (e.g., chromosomal aberrations) in their lymphocytes or exfoliated buccal cells. However, most of the studies, if not all, have a number of shortcomings that actually prevents any firm conclusion. Radiation dosimetry was lacking in all papers, but some of the investigations were flawed by much more severe imperfections. Large well-coordinated multidisciplinary investigations are needed in order to reach any robust conclusion. PMID:19073278

  9. 47 CFR 1.1310 - Radiofrequency radiation exposure limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... exposure limits. The criteria listed in table 1 shall be used to evaluate the environmental impact of human..., “Evaluating Compliance with FCC-Specified Guidelines for Human Exposure to Radiofrequency Radiation.” Note to... Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz,”...

  10. Cardiovascular risk in operators under radiofrequency electromagnetic radiation.

    PubMed

    Vangelova, Katia; Deyanov, Christo; Israel, Mishel

    2006-03-01

    The aim of the study was to assess the long-term effects of radiofrequency electromagnetic radiation (EMR) on the cardiovascular system. Two groups of exposed operators (49 broadcasting (BC) station and 61 TV station operators) and a control group of 110 radiorelay station operators, matched by sex and age, with similar job characteristics except for the radiofrequency EMR were studied. The EMR exposure was assessed and the time-weighted average (TWA) was calculated. The cardiovascular risk factors arterial pressure, lipid profile, body mass index, waist/hip ratio, smoking, and family history of cardiovascular disease were followed. The systolic and diastolic blood pressure (SBP and DBP), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly higher in the two exposed groups. It was found that the radiofrequency EMR exposure was associated with greater chance of becoming hypertensive and dyslipidemic. The stepwise multiple regression equations showed that the SBP and TWA predicted the high TC and high LDL-C, while the TC, age and abdominal obesity were predictors for high SBP and DBP. In conclusion, our data show that the radiofrequency EMR contributes to adverse effects on the cardiovascular system. PMID:16503299

  11. Successful Treatment of Occipital Radiating Headache Using Pulsed Radiofrequency Therapy

    PubMed Central

    Lee, Sun Yeul; Jang, Dae Il; Noh, Chan

    2015-01-01

    Rheumatoid arthritis (RA) is a chronic inflammatory disease involving multiple joints. The cervical spine is often affected, and cases involving atlantoaxial joint can lead to instability. Anterior atlantoaxial subluxation in RA patients can lead to posterior neck pain or occipital headache because of compression of the C2 ganglion or nerve. Here, we report the successful treatment of a RA patient with occipital radiating headache using pulsed radiofrequency therapy at the C2 dorsal root ganglion. PMID:26279821

  12. Measuring Radiofrequency and Microwave Radiation from Varying Signal Strengths

    NASA Technical Reports Server (NTRS)

    Davis, Bette; Gaul, W. C.

    2007-01-01

    This viewgraph presentation discusses the process of measuring radiofrequency and microwave radiation from various signal strengths. The topics include: 1) Limits and Guidelines; 2) Typical Variable Standard (IEEE) Frequency Dependent; 3) FCC Standard 47 CFR 1.1310; 4) Compliance Follows Unity Rule; 5) Multiple Sources Contribute; 6) Types of RF Signals; 7) Interfering Radiations; 8) Different Frequencies Different Powers; 9) Power Summing - Peak Power; 10) Contribution from Various Single Sources; 11) Total Power from Multiple Sources; 12) Are You Out of Compliance?; and 13) In Compliance.

  13. Risk assessment and management of radiofrequency radiation exposure

    SciTech Connect

    Dabala, Dana; Surducan, Emanoil; Surducan, Vasile; Neamtu, Camelia

    2013-11-13

    Radiofrequency radiation (RFR) industry managers, occupational physicians, security department, and other practitioners must be advised on the basic of biophysics and the health effects of RF electromagnetic fields so as to guide the management of exposure. Information on biophysics of RFR and biological/heath effects is derived from standard texts, literature and clinical experiences. Emergency treatment and ongoing care is outlined, with clinical approach integrating the circumstances of exposure and the patient's symptoms. Experimental risk assessment model in RFR chronic exposure is proposed. Planning for assessment and monitoring exposure, ongoing care, safety measures and work protection are outlining the proper management.

  14. Risk assessment and management of radiofrequency radiation exposure

    NASA Astrophysics Data System (ADS)

    Dabala, Dana; Surducan, Emanoil; Surducan, Vasile; Neamtu, Camelia

    2013-11-01

    Radiofrequency radiation (RFR) industry managers, occupational physicians, security department, and other practitioners must be advised on the basic of biophysics and the health effects of RF electromagnetic fields so as to guide the management of exposure. Information on biophysics of RFR and biological/heath effects is derived from standard texts, literature and clinical experiences. Emergency treatment and ongoing care is outlined, with clinical approach integrating the circumstances of exposure and the patient's symptoms. Experimental risk assessment model in RFR chronic exposure is proposed. Planning for assessment and monitoring exposure, ongoing care, safety measures and work protection are outlining the proper management.

  15. Effects of 900 MHz radiofrequency radiation on skin hydroxyproline contents.

    PubMed

    Çam, Semra Tepe; Seyhan, Nesrin; Kavaklı, Cengiz; Çelikbıçak, Ömür

    2014-09-01

    The present study aimed to investigate the possible effect of pulse-modulated radiofrequency radiation (RFR) on rat skin hydroxyproline content, since skin is the first target of external electromagnetic fields. Skin hydroxyproline content was measured using liquid chromatography mass spectrometer method. Two months old male wistar rats were exposed to a 900 MHz pulse-modulated RFR at an average whole body specific absorption rate (SAR) of 1.35 W/kg for 20 min/day for 3 weeks. The radiofrequency (RF) signals were pulse modulated by rectangular pulses with a repetition frequency of 217 Hz and a duty cycle of 1:8 (pulse width 0.576 ms). A skin biopsy was taken at the upper part of the abdominal costa after the exposure. The data indicated that whole body exposure to a pulse-modulated RF radiation that is similar to that emitted by the global system for mobile communications (GSM) mobile phones caused a statistically significant increase in the skin hydroxyproline level (p = 0.049, Mann-Whitney U test). Under our experimental conditions, at a SAR less than the International Commission on Non-Ionizing Radiation Protection safety limit recommendation, there was evidence that GSM signals could alter hydroxyproline concentration in the rat skin. PMID:24760629

  16. 47 CFR 2.1091 - Radiofrequency radiation exposure evaluation: mobile devices.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Radiofrequency radiation exposure evaluation: mobile devices. 2.1091 Section 2.1091 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Radiofrequency Radiation Exposure...

  17. Effective Treatment of Chronic Radiation Proctitis Using Radiofrequency Ablation

    PubMed Central

    Zhou, Chao; Adler, Desmond C.; Becker, Laren; Chen, Yu; Tsai, Tsung-Han; Figueiredo, Marisa; Schmitt, Joseph M.; Fujimoto, James G.

    2009-01-01

    Endoscopic argon plasma coagulation and bipolar electrocautery are currently preferred treatments for chronic radiation proctitis, but ulcerations and strictures frequently occur. Radiofrequency ablation (RFA) has been successful for mucosal ablation in the esophagus. Here we report the efficacy of RFA with the BarRx Halo90 system in three patients with bleeding from chronic radiation proctitis. In all cases, the procedure was well tolerated and hemostasis was achieved after 1 or 2 RFA sessions. Re-epithelialization of squamous mucosa was observed over areas of prior hemorrhage. No stricturing or ulceration was seen on follow-up up to 19 months after RFA treatment. Real-time endoscopic optical coherence tomography (EOCT) visualized epithelialization and subsurface tissue microvasculature pre- and post-treatment, demonstrating its potential for follow-up assessment of endoscopic therapies. PMID:20593010

  18. Effect of radiofrequency radiation in cultured mammalian cells: A review.

    PubMed

    Manna, Debashri; Ghosh, Rita

    2016-01-01

    The use of mobile phone related technologies will continue to increase in the foreseeable future worldwide. This has drawn attention to the probable interaction of radiofrequency electromagnetic radiation with different biological targets. Studies have been conducted on various organisms to evaluate the alleged ill-effect on health. We have therefore attempted to review those work limited to in vitro cultured cells where irradiation conditions were well controlled. Different investigators have studied varied endpoints like DNA damage, cell cycle arrest, reactive oxygen species (ROS) formation, cellular morphology and viability to weigh the genotoxic effect of such radiation by utilizing different frequencies and dose rates under various irradiation conditions that include continuous or pulsed exposures and also amplitude- or frequency-modulated waves. Cells adapt to change in their intra and extracellular environment from different chemical and physical stimuli through organized alterations in gene or protein expression that result in the induction of stress responses. Many studies have focused on such effects for risk estimations. Though the effects of microwave radiation on cells are often not pronounced, some investigators have therefore combined radiofrequency radiation with other physical or chemical agents to observe whether the effects of such agents were augmented or not. Such reports in cultured cellular systems have also included in this review. The findings from different workers have revealed that, effects were dependent on cell type and the endpoint selection. However, contradictory findings were also observed in same cell types with same assay, in such cases the specific absorption rate (SAR) values were significant. PMID:27053138

  19. Assessment of occupational exposure to radiofrequency fields and radiation.

    PubMed

    Cooper, T G; Allen, S G; Blackwell, R P; Litchfield, I; Mann, S M; Pope, J M; van Tongeren, M J A

    2004-01-01

    The use of personal monitors for the assessment of exposure to radiofrequency fields and radiation in potential future epidemiological studies of occupationally exposed populations has been investigated. Data loggers have been developed for use with a commercially available personal monitor and these allowed personal exposure records consisting of time-tagged measurements of electric and magnetic field strength to be accrued over extended periods of the working day. The instrumentation was worn by workers carrying out tasks representative of some of their typical daily activities at a variety of radio sites. The results indicated significant differences in the exposures of workers in various RF environments. A number of measures of exposure have been examined with a view to assessing possible exposure metrics for epidemiological studies. There was generally a good correlation between a given measure of electric field strength and the same measure of magnetic field strength. PMID:15266067

  20. Evaluation of stray radiofrequency radiation emitted by electrosurgical devices.

    PubMed

    De Marco, M; Maggi, S

    2006-07-21

    Electrosurgery refers to the passage of a high-frequency, high-voltage electrical current through the body to achieve the desired surgical effects. At the same time, these procedures are accompanied by a general increase of the electromagnetic field in an operating room that may expose both patients and personnel to relatively high levels of radiofrequency radiation. In the first part of this study, we have taken into account the radiation emitted by different monopolar electrosurgical devices, evaluating the electromagnetic field strength delivered by an electrosurgical handle and straying from units and other electrosurgical accessories. As a summary, in the worst case a surgeon's hands are exposed to a continuous and pulsed RF wave whose magnetic field strength is 0.75 A m(-1) (E-field 400 V m(-1)). Occasionally stray radiation may exceed ICNIRP's occupational exposure guidelines, especially close to the patient return plate. In the second part of this paper, we have analysed areas of particular concern to prevent electromagnetic interference with some life-support devices (ventilators and electrocardiographic devices), which have failed to operate correctly. Most clinically relevant interference occurred when an electrosurgery device was used within 0.3 m of medical equipment. In the appendix, we suggest some practical recommendations intended to minimize the potential for electromagnetic hazards due to therapeutic application of RF energy. PMID:16825734

  1. Evaluation of stray radiofrequency radiation emitted by electrosurgical devices

    NASA Astrophysics Data System (ADS)

    DeMarco, M.; Maggi, S.

    2006-07-01

    Electrosurgery refers to the passage of a high-frequency, high-voltage electrical current through the body to achieve the desired surgical effects. At the same time, these procedures are accompanied by a general increase of the electromagnetic field in an operating room that may expose both patients and personnel to relatively high levels of radiofrequency radiation. In the first part of this study, we have taken into account the radiation emitted by different monopolar electrosurgical devices, evaluating the electromagnetic field strength delivered by an electrosurgical handle and straying from units and other electrosurgical accessories. As a summary, in the worst case a surgeon's hands are exposed to a continuous and pulsed RF wave whose magnetic field strength is 0.75 A m-1 (E-field 400 V m-1). Occasionally stray radiation may exceed ICNIRP's occupational exposure guidelines, especially close to the patient return plate. In the second part of this paper, we have analysed areas of particular concern to prevent electromagnetic interference with some life-support devices (ventilators and electrocardiographic devices), which have failed to operate correctly. Most clinically relevant interference occurred when an electrosurgery device was used within 0.3 m of medical equipment. In the appendix, we suggest some practical recommendations intended to minimize the potential for electromagnetic hazards due to therapeutic application of RF energy.

  2. Base-level management of radio-frequency radiation-protection program. Final report

    SciTech Connect

    Rademacher, S.E.; Montgomery, N.D.

    1989-04-01

    AFOEHL developed this report to assist the base-level aerospace medical team manage their radio-frequency radiation-protection program. This report supersedes USAFOEHL Report 80-42, 'A Practical R-F Guide for BEES.'

  3. Base-level management of radio-frequency radiation-protection program. Final report

    SciTech Connect

    Rademacher, S.E.; Montgomery, N.D.

    1989-04-01

    AFOEHL developed this report to assist the base-level aerospace medical team manage their radio-frequency radiation protection program. This report supersedes USAFOEHL Report 80-42, 'A practical R-F Guide for BEES.'

  4. Genotoxicity of radiofrequency radiation. DNA/Genetox Expert Panel.

    PubMed

    Brusick, D; Albertini, R; McRee, D; Peterson, D; Williams, G; Hanawalt, P; Preston, J

    1998-01-01

    During the past several years, concerns have been raised regarding the potential adverse effects of exposures to nonionizing radiation, particularly in the extremely low frequency (ELF) range (50 to 60 MHz) and radiofrequency radiation (RFR) with frequencies ranging from 30 KHz to 30,000 MHz. One focus of concern has been potential DNA interactions. Publications reviewing the genotoxicity of ELF radiation [McCann et al. (1993): Mutat Res 297(1):61-95; Murphy et al. (1993): Mutat Res 296:221-240; NAS (1997)], have been uniform in concluding that the weight of evidence does not indicate any genotoxic risk from exposure to this type of radiation. Concern that RFR may be associated with adverse biological effects [WHO, 1993], including recent allegations that they may be involved in the production of brain tumors in humans [Elmer-Dewit (1993): Time, February 8:42], has resulted in the production of a large number of publications describing the effects of RFR on the integrity of nucleic acids. Data from studies conducted in a frequency range from 800 to 3,000 MHz were reviewed and subjected to a weight-of-evidence evaluation. The evaluation focused on direct toxicological effects of RFR as well as on studies addressing basic biological responses to RFR at the cellular and molecular level. The data from over 100 studies suggest that RFR is not directly mutagenic and that adverse effects from exposure of organisms to high frequencies and high power intensities of RFR are predominantly the result of hyperthermia; however, there may be some subtle indirect effects on the replication and/or transcription of genes under relatively restricted exposure conditions. PMID:9707093

  5. A suggested limit for population exposure to radiofrequency radiation.

    PubMed

    Cahill, D F

    1983-07-01

    Unlike a number of other nations, the U.S. does not currently have guidelines for the exposure of the public to radiofrequency (RF) radiation. In order to determine whether the current data base was sufficient to support an interim determination of a limit for population exposure to RF radiation (0.5 MHz-100 GHz), a critical and comprehensive review of the available literature on the biological effects of RF radiation was recently completed. In the analysis of this data, a number of simplifying assumptions had to be employed; among them was the use of the specific absorption rate (SAR) as the mass-normalized, frequency-independent measure of RF energy input into biological systems. The biological effects reported in acceptable studies were assessed in terms of their associations with (1) core temperature increases, (2) SAR, (3) SAR as a percentage increase over resting metabolic rate, and (4) direct evidence for human effects. Based on information now available and analyzed from these four perspectives, a conservative SAR threshold value of approx. 0.4 W/kg is apparent. Since the unknowns and uncertainties are potentially significant, one might consider, from the standpoint of prudence, the further application of a safety factor of 10. Given the present state of knowledge, the resultant SAR limit of 0.04 W/kg is, in the author's opinion, unlikely to be associated with the adverse health effects in the general population. This SAR translates into a power density of approximately 200 mu W/cm2 in the human resonant frequency range of 30-300 MHz. PMID:6347972

  6. Cell oxidation-reduction imbalance after modulated radiofrequency radiation.

    PubMed

    Marjanovic, Ana Marija; Pavicic, Ivan; Trosic, Ivancica

    2015-01-01

    Aim of this study was to evaluate an influence of modulated radiofrequency field (RF) of 1800 MHz, strength of 30 V/m on oxidation-reduction processes within the cell. The assigned RF field was generated within Gigahertz Transversal Electromagnetic Mode cell equipped by signal generator, modulator, and amplifier. Cell line V79, was irradiated for 10, 30, and 60 min, specific absorption rate was calculated to be 1.6 W/kg. Cell metabolic activity and viability was determined by MTT assay. In order to define total protein content, colorimetric method was used. Concentration of oxidised proteins was evaluated by enzyme-linked immunosorbent assay. Reactive oxygen species (ROS) marked with fluorescent probe 2',7'-dichlorofluorescin diacetate were measured by means of plate reader device. In comparison with control cell samples, metabolic activity and total protein content in exposed cells did not differ significantly. Concentrations of carbonyl derivates, a product of protein oxidation, insignificantly but continuously increase with duration of exposure. In exposed samples, ROS level significantly (p < 0.05) increased after 10 min of exposure. Decrease in ROS level was observed after 30-min treatment indicating antioxidant defence mechanism activation. In conclusion, under the given laboratory conditions, modulated RF radiation might cause impairment in cell oxidation-reduction equilibrium within the growing cells. PMID:25119294

  7. REDUCTION IN METABOLIC HEAT PRODUCTION DURING EXPOSURE TO RADIO-FREQUENCY RADIATION IN THE RAT

    EPA Science Inventory

    Male Sprague-Dawley rats were maintained at an ambient temperature (Ta) of 10 C and exposed to 600 MHz radiofrequency (RF) radiation while metabolic rate (MR) was measured by indirect calorimetry. RF radiation exposures were made in a waveguide-type system which permitted the con...

  8. NORMALIZING THE THERMAL EFFECTS OF RADIOFREQUENCY RADIATION: BODY MASS VERSUS TOTAL BODY SURFACE AREA

    EPA Science Inventory

    The current guideline for exposure to radiofrequency radiation (RFR) of 0.4 W/kg may have inadvertently been set to high. The guideline is based on the rate of RFR absorption normalized with respect to body mass. Based primarily on data for work stoppage in the rat, the 0.4 W/kg ...

  9. CHRONIC EXPOSURE OF RATS TO 100-MHZ (CW) RADIOFREQUENCY RADIATION: ASSESSMENT OF BIOLOGICAL EFFECTS

    EPA Science Inventory

    A multidisciplinary approach was employed to assess the possible biological effects of chronic exposure of rats to 100-MHz continuous wave (CW) radiofrequency (RF) radiation. A group of 20 time-bred rats were exposed in a transverse electronmagnetic mode (TEM) transmission line t...

  10. COMPARATIVE THERMOREGULATORY RESPONSE TO PASSIVE HEAT LOADING BY EXPOSURE TO RADIOFREQUENCY RADIATION

    EPA Science Inventory

    Colonic and tail skin temperature of the unrestrained Fischer rat were measured immediately after a 90 min exposure to 600 MHz radiofrequency radiation in a waveguide-type system. Ambient temperature (Ta) was maintained at either 20, 28, or 35 C. The specific absorption rate (SAR...

  11. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., including microwave frequencies. 179.30 Section 179.30 Food and Drugs FOOD AND DRUG ADMINISTRATION... for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be safely used for heating food under the following conditions: (a) The...

  12. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., including microwave frequencies. 179.30 Section 179.30 Food and Drugs FOOD AND DRUG ADMINISTRATION... for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be safely used for heating food under the following conditions: (a) The...

  13. SCALING THE PHYSIOLOGICAL EFFECTS OF EXPOSURE TO RADIOFREQUENCY ELECTROMAGNETIC RADIATION: CONSEQUENCES OF BODY SIZE

    EPA Science Inventory

    The authors have demonstrated that a comparative analysis of the physiological effects of exposure of laboratory mammals to radiofrequency electromagnetic radiation (RFR) may be useful in predicting exposure thresholds for humans if the effect is assumed to be due only to heating...

  14. BODY TEMPERATURE IN THE MOUSE, HAMSTER, AND RAT EXPOSED TO RADIOFREQUENCY RADIATION: AN INTERSPECIES COMPARISON

    EPA Science Inventory

    Colonic temperatures of BALB/c and CBA/J mice, golden hamsters, and Sprague-Dawley rats were taken immediately after exposure for 90 min to radiofrequency (RF) radiation. Exposures were made in 2450 MHz (mouse and hamster) or 600 MHz (rat) waveguide exposure systems while the dos...

  15. TEMPERATURE REGULATION IN THE UNRESTRAINED RABBIT DURING EXPOSURE TO 600 MHZ RADIOFREQUENCY RADIATION

    EPA Science Inventory

    Six male New Zealand white rabbits were individually exposed to 600 MHz radiofrequency (RF) radiation for 90 min in a waveguide exposure system at an ambient temperature (Ta) of 20 or 30 C. Immediately after exposure, the rabbit was removed from the exposure chamber and its colon...

  16. DOSE DEPENDENCE OF ACETYLCHOLINESTERASE ACTIVITY IN NEUROBLASTOMA CELLS EXPOSED TO MODULATED RADIOFREQUENCY RADIATION

    EPA Science Inventory

    Radiofrequency radiation (RFR) at 915 and at 147 MHz, when sinusoidally amplitude modulated (AM) at 16 Hz, has been shown to enhance release of calcium ions from neuroblastoma cells in culture. he dose response is unusual, consisting of two power density 'windows' in which enhanc...

  17. Effects of radiofrequency radiation on rabbit kidney: a morphological and immunological study

    SciTech Connect

    Accinni, L.; De Martino, C.; Mariutti, G.

    1988-08-01

    The histopathology of the acute and chronic kidney reaction to low-frequency nonionizing electromagnetic radiation was evaluated in New Zealand white rabbits treated with multiple exposure to 27.12-MHz radiofrequencies. At the end of treatment, the animals exhibited focal tubular necrosis and focal and segmental glomerular sclerosis which in a few months evolved into a membranous nephropathy. The latter was characterized by a diffuse, granular localization of rabbit gamma-globulin and complement in most glomeruli and by electron-dense deposits in the subepithelial zone of the glomerular capillary walls, suggesting that these glomerular changes are induced by the localization of antigen-antibody complexes. The data obtained provide strong evidence for the potential nephrotoxicity of radiofrequency radiation and indicate that these nonionizing types of radiation may be capable of eliciting autoimmune phenomena that are likely responsible for the evolution of renal disease in rabbits.

  18. FURTHER EVIDENCE OF AN INVERSE RELATION BETWEEN MAMMALIAN BODY MASS AND SENSITIVITY TO RADIO-FREQUENCY ELECTROMAGNETIC RADIATION

    EPA Science Inventory

    The principal objectives of the paper under criticism were to interrelate the effects of ambient temperature and intensity of exposure to radiofrequency electromagnetic radiation (RFR) on the activity of a single thermoregulatory effector, evaporative heat loss (EHL) and (ii) to ...

  19. Radiotelemetry and wildlife: Highlighting a gap in the knowledge on radiofrequency radiation effects.

    PubMed

    Balmori, Alfonso

    2016-02-01

    Radio transmitters and associated devices may induce negative effects that can bias the results of ongoing research. The main documented effects of radio transmitters on animals include reduced survival, decreased productivity, changes in behaviour and movement patterns and a biased sex ratio. The only factors that have claimed responsibility for these possible damages are the weight of the radio transmitter and associated devices, and the attachment type. The electromagnetic radiation produced by radio transmitters has not been considered so far in research. There have been no studies evaluating the effects of non-ionising electromagnetic radiation (radiofrequency signals) necessary for tracking, although the problems found were significantly associated with the length of time that animals had been carrying their radio transmitters. Similar problems as those in radiotracked animals have been found in numerous studies with animals exposed to radiofrequency radiation for a sufficient amount of time. Laboratory scientists investigating the orientation of animals know they have to shield the place where experiments are performed to prevent interference from man-made radiation, as anthropogenic signals may distort the results. It is paradoxical that, at the same time, field scientists investigating the movements and other aspects of animal biology are providing animals with radio transmitters that emit the same type of radiation, since this may affect the results concerning their orientation and movement. This paper identifies gaps in the knowledge that should be investigated in-depth. The possibility that the radiofrequency radiation from radiotracking devices is responsible for the findings should be considered. Considering this factor may allow researchers to best understand the long-term effects found. PMID:26615484

  20. Biological studies with continuous-wave radiofrequency (28 MHz) radiation

    SciTech Connect

    Wright, N.A.; Borland, R.G.; Cookson, J.H.; Coward, R.F.; Davies, J.A.; Nicholson, A.N.; Christie, J.L.; Flanagan, N.G.; Goodridge, V.D.

    1984-03-01

    Effects of high-frequency (28 MHz) continous-wave radiation have been studied in the rat and monkey. No histopathological or hematological changes could be attributed to the radiation. In the monkey there was an increase in urinary calcium concentration which was most likely due to restricted movement. In the rat there was reduced uptake of iodine by the thyroid, lower levels of plasma thyroid-stimulating hormone, and reduced ratio of protein bound to nonprotein bound iodine. Food consumption was also decreased. The changes are likely to have arisen as a compensatory response to an induced heat load. A nonthermal effect of continuous-wave high-frequency radiation has not been shown in this study. The effects were likely to be associated with either physiological compensation for induced heating or restriction of movement.

  1. ELISA reader does not interfere by mobile phone radiofrequency radiation

    PubMed Central

    Mortazavi, Seyyed Mohammad Javad; Baradaran-Ghahfarokhi, Hamid Reza; Abdi, Mohammad Reza; Baradaran-Ghahfarokhi, Milad; Mostafavi, Nayyer Sadat; Mahmoudi, Golshan; Berenjkoub, Nafiseh; Akmali, Zahra; Hossein-Beigi, Fahimeh; Arsang, Vajiheh

    2016-01-01

    Background: The increasing number of mobile phones can physically cause electromagnetic interference (EMI) in medical environments; can also cause errors in immunoassays in laboratories. The ELISA readers are widely used as a useful diagnostic tool for Enzymun colorimetric assay in medicine. The aim of this study was to investigate whether the ELISA reader could be interfered by the exposure to the 900 MHz cell phones in the laboratory. Materials and Methods: Human serum samples were collected from 14 healthy donors (9 women and 5 men) and each sample was divided into four aliquots and was placed into four batches for the in-vitro quantitative determination of human chorionic gonadotropin (hCG). During colorimetric reading of the first, second, and third batches, the ELISA reader (Stat Fax 2100, Awareness Technology, Inc., USA) was exposed to 0.5, 1.0, and 2.0 W exposure of 900 MHz radiation, respectively. For the forth batch (control group), no radiation was applied. All experiments were performed comparing ELISA read out results of the I, II, and III batches with the control batch, using the Wilcoxon test with criterion level of P = 0.050. Results: The final scores in the exposed batches I, II, and III were not statistically significant relative to the control batch (P > 0.05). The results showed that 900 MHz radiation exposure did not alter the ELISA measured levels of hCG hormone in I (P = 0.219), II (P = 0.909), and III (P = 0.056) batches compared to the control batch. Conclusion: This study showed that ELISA reader does not interfere by mobile phone RF radiation at a closed contact (less than 5 cm distance). However, we recommend that medical institutions discuss these issues in the context of their specific use of technologies and frame a policy that is clear and straightforward to guide staff, patients, and visitors. PMID:27376040

  2. Radiofrequency radiation-induced calcium ion efflux enhancement from human and other neuroblastoma cells in culture

    SciTech Connect

    Dutta, S.K.; Ghosh, B.; Blackman, C.F.

    1989-01-01

    To test the generality of radiofrequency radiation-induced changes in /sup 45/Ca2+ efflux from avian and feline brain tissues, human neuroblastoma cells were exposed to electromagnetic radiation at 147 MHz, amplitude-modulated (AM) at 16 Hz, at specific absorption rates (SAR) of 0.1, 0.05, 0.01, 0.005, 0.001, and 0.0005 W/kg. Significant /sup 45/Ca2+ efflux was obtained at SAR values of 0.05 and 0.005 W/kg. Enhanced efflux at 0.05 W/kg peaked at the 13-16 Hz and at the 57.5-60 Hz modulation ranges. A Chinese hamster-mouse hybrid neuroblastoma was also shown to exhibit enhanced radiation-induced /sup 45/Ca2+ efflux at an SAR of 0.05 W/kg, using 147 MHz, AM at 16 Hz. These results confirm that amplitude-modulated radiofrequency radiation can induce responses in cells of nervous tissue origin from widely different animal species, including humans. The results are also consistent with the reports of similar findings in avian and feline brain tissues and indicate the general nature of the phenomenon.

  3. Perturbations of plant leaflet rhythms caused by electromagnetic radio-frequency radiation.

    PubMed

    Ellingsrud, S; Johnsson, A

    1993-01-01

    The minute-range up and down rhythms of the lateral leaflets of Desmodium gyrans has been studied when exposed to electromagnetic radiation in the radio-frequency (RF) range. The RF radiation was applied as homogeneous 27.12 MHz fields in specially-designed exposure cells(and in some cases as non-homogeneous radiation of 27 MHz, amplitude modulated by 50 Hz, in front of commercial diathermy equipment). All fields were applied as pulses. We report effects in the leaflet rhythms such as temporary changes in the amplitude, period, and phase. The radiation could also cause temporary or complete cessations of the rhythms. The lowest dose (8 W/cm2) used was still effective. PMID:8323575

  4. Variations of melatonin and stress hormones under extended shifts and radiofrequency electromagnetic radiation.

    PubMed

    Vangelova, Katia Koicheva; Israel, Mishel Salvador

    2005-01-01

    We studied the time-of-day variations in urinary levels of 6-sulphatoxy-melatonin and three stress hormones in operators working fast-rotating extended shifts under radiofrequency electromagnetic radiation (EMR). The excretion rate of the hormones was monitored by radioimmunoassay and spectrofluorimetry at 4-hour intervals in a group of 36 male operators comprising 12 broadcasting station operators, 12 TV station operators, and a control group of 12 satellite station operators. Measuring the time-weighted average (TWA) of EMR exposure revealed a high-level of exposure in broadcasting station operators (TWAmean= 3.10 microW/ cm2, TWAmax = 137.00 microW/cm2), a low-level in TV station operators (TWAmean = 1.89 microW/cm2, TWAmax = 5.24 microW/cm2), and a very low level in satellite station operators. The differences among the groups remained the same after confounding factors were taken into account. Radiofrequency EMR had no effect on the typical diurnal pattern of 6-sulphatoxymelatonin. High-level radiofrequency EMR exposure significantly increased the excretion rates of cortisol (p < 0.001), adrenaline (p = 0.028), and noradrenaline (p < 0.000), whereas changes under low-level exposure did not reach significance. The 24-hour excretion of cortisol and noradrenaline correlated with TWAmean and TWAmax. In conclusion, the excretion of 6-sulphatoxymelatonin retained a typical diurnal pattern under fast-rotating extended shifts and radiofrequency EMR, but showed an exposure-effect relation with stress hormones. PMID:16121836

  5. ECG changes in factory workers exposed to 27.2  MHz radiofrequency radiation.

    PubMed

    Chen, Qingsong; Xu, Guoyong; Lang, Li; Yang, Aichu; Li, Shilin; Yang, Liwen; Li, Chaolin; Huang, Hanlin; Li, Tao

    2013-05-01

    To research the effect of 27.2 MHz radiofrequency radiation on electrocardiograms (ECG), 225 female workers operating radiofrequency machines at a shoe factory were chosen as the exposure group and 100 female workers without exposure from the same factory were selected as the control group. The 6 min electric field strength that the female workers were exposed to was 64.0 ± 25.2 V/m (mean ± SD), which exceeded 61 V/m, the International Commission on Non-Ionizing Radiation Protection reference root mean square levels for occupational exposure. A statistical difference was observed between the exposed group and the control group in terms of the rate of sinus bradycardia (χ(2)  = 11.48, P = 0.003). When several known risk factors for cardiovascular disease were considered, including smoking, age, alcohol ingestion habit, and so on, the exposure duration was not an effective factor for ECG changes, sinus arrhythmia, or sinus bradycardia according to α = 0.05, while P = 0.052 for sinus arrhythmia was very close to 0.05. We did not find any statistical difference in heart rate, duration of the QRS wave (ventricular depolarization), or corrected QT intervals (between the start of the Q wave and end of the T wave) between the exposed and control groups. Occupational exposure to radiofrequency radiation was not found to be a cause of ECG changes after consideration of the confounding factors. PMID:23280584

  6. RADIOFREQUENCY RADIATION-INDUCED CALCIUM-ION-EFFLUX ENHANCEMENT FROM HUMAN AND OTHER NEUROBLASTOMA CELLS IN CULTURE

    EPA Science Inventory

    In order to test the generality of radiofrequency-radiation-induced change in alteration 45Ca2+ efflux from avian and feline brain tissues, human neuroblastoma cells were exposed to electromagnetic radiation at 147 MHz, amplitude modulated (AM) at 16 Hz, at specific absorption ra...

  7. Outdoor radiofrequency radiation levels in the West Bank-Palestine.

    PubMed

    Lahham, Adnan; Hammash, Alaa

    2012-05-01

    This work presents the results of exposure levels to radio frequency (RF) emission from different sources in the environment of the West Bank-Palestine. These RF emitters include FM and TV broadcasting stations and mobile phone base stations. Power densities were measured at 65 locations distributed over the West Bank area. These locations include mainly centres of the major cities. Also a 24 h activity level was investigated for a mobile phone base station to determine the maximum activity level for this kind of RF emitters. All measurements were conducted at a height of 1.7 m above ground level using hand held Narda SRM 3000 spectrum analyzer with isotropic antenna capable of collecting RF signals in the frequency band from 75 MHz to 3 GHz. The average value of power density resulted from FM radio broadcasting in all investigated locations was 0.148 μW cm(-2), from TV broadcasting was 0.007 μW cm(-2) and from mobile phone base station was 0.089 μW cm(-2). The maximum total exposure evaluated at any location was 3.86 μW cm(-2). The corresponding exposure quotient calculated for this site was 0.02. This value is well below unity indicating compliance with the International Commission on non-ionising Radiation protection guidelines. Contributions from all relevant RF sources to the total exposure were evaluated and found to be ~62 % from FM radio, 3 % for TV broadcasting and 35 % from mobile phone base stations. The average total exposure from all investigated RF sources was 0.37 μW cm(-2). PMID:21835841

  8. Thermal responses to 5. 6-GHz radiofrequency radiation in anesthetized rats: effect of chlorpromazine

    SciTech Connect

    Jauchem, J.R.; Frei, M.R.; Heinmets, F.

    1988-01-01

    Anesthetized rats were exposed to 5.6-GHz continuous wave radiofrequency radiation at an average power density of 60 mW/cm2 (average specific absorption rate 12 W/kg). Exposure was performed to raise colonic temperature from 38.5 to 39.5 degrees C. Following acute administration of chlorpromazine, body temperature exhibited a faster return to baseline temperature when exposure was discontinued. When exposure was initiated at 38.5 degrees C and continued until lethal temperatures resulted, chlorpromazine-treated animals exhibited significantly shorter survival times than saline-treated animals. Thus, although chlorpromazine enhanced thermo-regulatory efficiency at colonic temperatures below 39.5 degrees C, the drug caused increased susceptibility to terminal radiofrequency radiation exposure. The present results, when compared to previous studies of irradiation at 2.8 GHz, indicate that the effects of chlorpromazine on thermal responses to RFR during intermittent and terminal exposure are similar at both 2.8 and 5.6 GHz.

  9. Immune responses of a wall lizard to whole-body exposure to radiofrequency electromagnetic radiation.

    PubMed

    Mina, Despoina; Sagonas, Kostas; Fragopoulou, Adamantia F; Pafilis, Panayiotis; Skouroliakou, Aikaterini; Margaritis, Lukas H; Tsitsilonis, Ourania E; Valakos, Efstratios D

    2016-03-01

    Purpose During the last three decades, the number of devices that emit non-ionizing electromagnetic radiation (EMR) at the wireless communication spectrum has rapidly increased and possible effects on living organisms have become a major concern. The purpose of this study was to investigate the effects of radiofrequency EMR emitted by a widely used wireless communication device, namely the Digital Enhanced Communication Telephony (DECT) base, on the immune responses of the Aegean wall lizard (Podarcis erhardii). Materials and methods Adult male lizards were exposed 24 h/day for 8 weeks to 1880-1900 MHz DECT base radiation at average electric field intensity of 3.2 V/m. Immune reactivity was assessed using the phytohemagglutinin (PHA) skin swelling and mixed lymphocyte reaction (MLR) tests. Results Our results revealed a noticeable suppression (approximately 45%) of inflammatory responses in EMR-exposed lizards compared to sham-exposed animals. T cell-mediated responses were marginally affected. Conclusion Daily radiofrequency EMR exposure seems to affect, at least partially, the immunocompetence of the Aegean wall lizard. PMID:26853383

  10. Assessment of radiofrequency radiation within the vicinity of some GSM base stations in Ghana.

    PubMed

    Deatanyah, P; Amoako, J K; Fletcher, J J; Asiedu, G O; Adjei, D N; Dwapanyin, G O; Amoatey, E A

    2012-08-01

    A radiofrequency (RF) electromagnetic radiation safety survey had been carried out at public access points in 46 towns with 76 Global Systems for Mobile communication cell sites in two major cities in Ghana. The objective was to determine the levels of RF field in residential areas, schools and market places, and compare the measured results with the guidelines set by the International Commission of Non-Ionising Radiation (ICNIRP). Measurements were made with log-periodic antenna coupled with spectrum analyzer. The results varied from 0.85 to 1.07 mW m(-2) and 0.78 to 1.19 mW m(-2) for the transmission frequencies of 900 and 1800 MHz, respectively. The result generally shows a compliance with the ICNIRP limit of 0.024 % but was 108 times higher than a similar survey carried out in Ghana 2 y ago. PMID:22262818

  11. Induction of adaptive response in human blood lymphocytes exposed to radiofrequency radiation.

    PubMed

    Sannino, Anna; Sarti, Maurizio; Reddy, Siddharth B; Prihoda, Thomas J; Vijayalaxmi; Scarfì, Maria Rosaria

    2009-06-01

    The incidence of micronuclei was evaluated to assess the induction of an adaptive response to non-ionizing radiofrequency (RF) radiation in peripheral blood lymphocytes collected from five different human volunteers. After stimulation with phytohemagglutinin for 24 h, the cells were exposed to an adaptive dose of 900 MHz RF radiation used for mobile communications (at a peak specific absorption rate of 10 W/kg) for 20 h and then challenged with a single genotoxic dose of mitomycin C (100 ng/ml) at 48 h. Lymphocytes were collected at 72 h to examine the frequency of micronuclei in cytokinesis-blocked binucleated cells. Cells collected from four donors exhibited the induction of adaptive response (i.e., responders). Lymphocytes that were pre-exposed to 900 MHz RF radiation had a significantly decreased incidence of micronuclei induced by the challenge dose of mitomycin C compared to those that were not pre-exposed to 900 MHz RF radiation. These preliminary results suggested that the adaptive response can be induced in cells exposed to non-ionizing radiation. A similar phenomenon has been reported in cells as well as in animals exposed to ionizing radiation in several earlier studies. However, induction of adaptive response was not observed in the remaining donor (i.e., non-responder). The incidence of micronuclei induced by the challenge dose of mitomycin C was not significantly different between the cells that were pre-exposed and unexposed to 900 MHz RF radiation. Thus the overall data indicated the existence of heterogeneity in the induction of an adaptive response between individuals exposed to RF radiation and showed that the less time-consuming micronucleus assay can be used to determine whether an individual is a responder or non-responder. PMID:19580480

  12. Scaling the physiological effects of exposure to radiofrequency electromagnetic radiation: consequences of body size

    SciTech Connect

    Gordon, C.J.; Ferguson, J.H.

    1984-01-01

    The authors have demonstrated that a comparative analysis of the physiological effects of exposure of laboratory mammals to radiofrequency electromagnetic radiation (RFR) may be useful in predicting exposure thresholds for humans if the effect is assumed to be due only to heating of tissue. The threshold specific absorption rate (SAR) necessary to affect a thermoregulatory parameter shows an inverse and linear relationship to body mass. The inverse relationship between threshold SAR and body mass is attributed to a surface area: body mass relationship. In comparison to small mammals, relatively large mammals have a reduced capacity to dissipate an internal heat load passively, and are therefore physiologically more sensitive to RFR exposure. The threshold for a thermoregulatory response depends on the type of response measured, species, ambient temperature, etc.

  13. Epidemiological studies of human exposures to radiofrequency radiation. A critical review.

    PubMed

    Roberts, N J; Michaelson, S M

    1985-01-01

    The health effects to exposure to radiofrequency radiation (RFR) remain undefined and controversial. Epidemiological studies of human exposures to RFR are confounded by difficulties in determining the type and true extent of exposures, in selecting an appropriate control group for comparisons, in determining the existence and influence of many concomitant environmental factors, and in establishing the presence or measuring the frequency or severity of subjective complaints was well as objective findings in the studied populations. This paper reviews reported RFR effects on general health, growth and development, physiological systems such as the cardiovascular and nervous systems, and organs such as the eye. Criteria for reliable epidemiological studies are presented to allow critical analysis of such reports. PMID:3905624

  14. Normalizing the thermal effects of radiofrequency radiation: body mass versus total body surface area

    SciTech Connect

    Gordon, C.J.

    1987-01-01

    The current guideline for exposure to radiofrequency radiation (RFR) of 0.4 W/kg may have inadvertently been set too high. The guideline is based on the rate of RFR absorption normalized with respect to body mass. Based primarily on data for work stoppage in the rat, the 0.4 W/kg guideline was calculated by the dividing the 4.0 W/kg dose by a safety factor of 10. However, if the RFR dose in the rat had been normalized with respect to surface area rather than body mass, the exposure guideline would be 2.3 W/sq m which translates, for a 80 kg adult, to an SAR of approximately 0.06 W/kg. Thus, the current RF exposure guideline may be several-fold greater than originally intended.

  15. Looking at the other side of the coin: the search for possible biopositive cognitive effects of the exposure to 900 MHz GSM mobile phone radiofrequency radiation

    PubMed Central

    2014-01-01

    Although exposure to electromagnetic radiation in radiofrequency range has caused a great deal of concern globally, radiofrequency radiation has many critical applications in both telecommunication and non-communication fields. The induction of adaptive response phenomena by exposure to radiofrequency radiation as either increased resistance to a subsequent dose of ionizing radiation or resistance to a bacterial infection has been reported recently. Interestingly, the potential beneficial effects of mobile phone radiofrequency radiation are not only limited to the induction of adaptive phenomena. It has previously been indicated that the visual reaction time of university students significantly decreased after a 10 min exposure to radiofrequency radiation emitted by a mobile phone. Furthermore, it has been revealed that occupational exposures to radar radiations decreased the reaction time in radar workers. Based on these findings, it can be hypothesized that in special circumstances, these exposures might lead to a better response of humans to different hazards. Other investigators have also provided evidence that confirms the induction of RF-induced cognitive benefits. Furthermore, some recent reports have indicated that RF radiation may play a role in protecting against cognitive impairment in Alzheimer’s disease. In this light, a challenging issue will arise if there are other RF-induced stimulating effects. It is also challenging to explore the potential applications of these effects. Further research may shed light on dark areas of the health effects of short and long-term human exposure to radiofrequency radiation. PMID:24843789

  16. Looking at the other side of the coin: the search for possible biopositive cognitive effects of the exposure to 900 MHz GSM mobile phone radiofrequency radiation.

    PubMed

    Mortazavi, Seyed Ali Reza; Tavakkoli-Golpayegani, Ali; Haghani, Masoud; Mortazavi, Seyed Mohammad Javad

    2014-01-01

    Although exposure to electromagnetic radiation in radiofrequency range has caused a great deal of concern globally, radiofrequency radiation has many critical applications in both telecommunication and non-communication fields. The induction of adaptive response phenomena by exposure to radiofrequency radiation as either increased resistance to a subsequent dose of ionizing radiation or resistance to a bacterial infection has been reported recently. Interestingly, the potential beneficial effects of mobile phone radiofrequency radiation are not only limited to the induction of adaptive phenomena. It has previously been indicated that the visual reaction time of university students significantly decreased after a 10 min exposure to radiofrequency radiation emitted by a mobile phone. Furthermore, it has been revealed that occupational exposures to radar radiations decreased the reaction time in radar workers. Based on these findings, it can be hypothesized that in special circumstances, these exposures might lead to a better response of humans to different hazards. Other investigators have also provided evidence that confirms the induction of RF-induced cognitive benefits. Furthermore, some recent reports have indicated that RF radiation may play a role in protecting against cognitive impairment in Alzheimer's disease. In this light, a challenging issue will arise if there are other RF-induced stimulating effects. It is also challenging to explore the potential applications of these effects. Further research may shed light on dark areas of the health effects of short and long-term human exposure to radiofrequency radiation. PMID:24843789

  17. Cancer in radar technicians exposed to radiofrequency/microwave radiation: sentinel episodes.

    PubMed

    Richter, E; Berman, T; Ben-Michael, E; Laster, R; Westin, J B

    2000-01-01

    Controversy exists concerning the health risks from exposures to radiofrequency/microwave irradiation (RF/MW). The authors report exposure-effect relationships in sentinel patients and their co-workers, who were technicians with high levels of exposure to RF/MW radiation. Information about exposures of patients with sentinel tumors was obtained from interviews, medical records, and technical sources. One patient was a member of a cohort of 25 workers with six tumors. The authors estimated relative risks for cancer in this group and latency periods for a larger group of self-reported individuals. Index patients with melanoma of the eye, testicular cancer, nasopharyngioma, non-Hodgkin's lymphoma, and breast cancer were in the 20-37-year age group. Information about work conditions suggested prolonged exposures to high levels of RF/MW radiation that produced risks for the entire body. Clusters involved many different types of tumors. Latency periods were extremely brief in index patients and a larger self-reported group. The findings suggest that young persons exposed to high levels of RF/MW radiation for long periods in settings where preventive measures were lax were at increased risk for cancer. Very short latency periods suggest high risks from high-level exposures. Calculations derived from a linear model of dose-response suggest the need to prevent exposures in the range of 10-100 microw/cm(2). PMID:10926722

  18. Comparative thermoregulatory response to passive heat loading by exposure to radiofrequency radiation

    SciTech Connect

    Gordon, C.J.; Ali, J.S.

    1987-01-01

    Colonic and tail-skin temperature of the unrestrained Fischer rat were measured immediately after a 90-min exposure to 600-MHz radiofrequency radiation in a waveguide-type system. Ambient temperature (Ta) was maintained at either 20, 28, or 35 C. The specific absorption rate (SAR) in dimensions of W/kg was controlled at a constant level through a feedback control circuit. The SAR needed to elevate colonic and tail-skin temperature decreased with increasing Ta. For example, a 0.5 C elevation in colonic temperature occurred at SAR's of 4.3, 0.9, and 0.5 W/kg when Ta was maintained at 20, 28, and 35 C, respectively. Data from this study were combined with data from earlier studies to assess the impact of varying Ta on the thermogenic effect of RF radiation in different species. In species ranging in mass from 0.02 to 3.2 kg, a double logarithmic plot of body mass versus SAR needed to elevate colonic temperature by 0.5 C was linear and inverse with a high goodness of fit (r(2) = -0.94). The highly correlated allometric relationship shows that, as body mass decreases, the relative impact of Ta on the thermogenic effect of RF radiation increases.

  19. Exposure to radiofrequency radiation induces oxidative stress in duckweed Lemna minor L.

    PubMed

    Tkalec, Mirta; Malarić, Kresimir; Pevalek-Kozlina, Branka

    2007-12-15

    Widespread use of radiofrequency radiation emitting devices increased the exposure to electromagnetic fields (EMFs) from 300 MHz to 300 GHz. Various biological effects of exposure to these fields have been documented so far, but very little work has been carried out on plants. The aim of the present work was to investigate the physiological responses of the plant Lemna minor after exposure to radiofrequency EMFs, and in particular, to clarify the possible role of oxidative stress in the observed effects. Duckweed was exposed for 2 h to EMFs of 400 and 900 MHz at field strengths of 10, 23, 41 and 120 V m(-1). The effect of a longer exposure time (4 h) and modulation was also investigated. After exposure, parameters of oxidative stress, such as lipid peroxidation, H(2)O(2) content, activities and isoenzyme pattern of antioxidative enzymes as well as HSP70 expression were evaluated. At 400 MHz, lipid peroxidation and H(2)O(2) content were significantly enhanced in duckweed exposed to EMFs of 23 and 120 V m(-1) while other exposure treatments did not have an effect. Compared to the controls, the activities of antioxidative enzymes showed different behaviour: catalase (CAT) activity increased after most exposure treatments while pyrogallol (PPX) and ascorbate peroxidase (APX) activities were not changed. Exceptions were reduced PPX and APX activity after longer exposure at 23 V m(-1) and increased PPX activity after exposures at 10 and 120 V m(-1). By contrast, at 900 MHz almost all exposure treatments significantly increased level of lipid peroxidation and H(2)O(2) content but mostly decreased PPX activity and did not affect CAT activity. Exceptions were exposures to a modulated field and to the field of 120 V m(-1) which increased PPX and CAT activity. At this frequency APX activity was significantly decreased after exposure at 10 V m(-1) and longer exposure at 23 V m(-1) but it increased after a shorter exposure at 23 V m(-1). At both frequencies no differences in

  20. Male reproductive health under threat: Short term exposure to radiofrequency radiations emitted by common mobile jammers

    PubMed Central

    Mortazavi, SMJ; Parsanezhad, ME; Kazempour, M; Ghahramani, P; Mortazavi, AR; Davari, M

    2013-01-01

    BACKGROUND: Modern life prompted man to increasingly generate, transmit and use electricity that leads to exposure to different levels of electromagnetic fields (EMFs). Substantial evidence indicates that exposure to common sources of EMF such as mobile phones, laptops or wireless internet-connected laptops decreases human semen quality. In some countries, mobile jammers are occasionally used in offices, shrines, conference rooms and cinemas to block the signal. AIMS: To the best of our knowledge, this is the first study to investigate the effect of short term exposure of human sperm samples to radiofrequency (RF) radiations emitted by common mobile jammers. SUBJECTS AND METHODS: Fresh semen samples were collected by masturbation from 30 healthy donors who had referred to Infertility Treatment Center at the Mother and Child Hospital with their wives. Female problem was diagnosed as the reason for infertility in these couples. STATISTICAL ANALYSIS: T-test and analysis of variance were used to show statistical significance. RESULTS: The motility of sperm samples exposed to jammer RF radiation for 2 or 4 h were significantly lower than those of sham-exposed samples. These findings lead us to the conclusion that mobile jammers may significantly decrease sperm motility and the couples’ chances of conception. CONCLUSION: Based on these results, it can be suggested that in countries that have not banned mobile jammer use, legislations should be urgently passed to restrict the use of these signal blocking devices in public or private places. PMID:24082653

  1. Oxidative mechanisms of biological activity of low-intensity radiofrequency radiation.

    PubMed

    Yakymenko, Igor; Tsybulin, Olexandr; Sidorik, Evgeniy; Henshel, Diane; Kyrylenko, Olga; Kyrylenko, Sergiy

    2016-01-01

    This review aims to cover experimental data on oxidative effects of low-intensity radiofrequency radiation (RFR) in living cells. Analysis of the currently available peer-reviewed scientific literature reveals molecular effects induced by low-intensity RFR in living cells; this includes significant activation of key pathways generating reactive oxygen species (ROS), activation of peroxidation, oxidative damage of DNA and changes in the activity of antioxidant enzymes. It indicates that among 100 currently available peer-reviewed studies dealing with oxidative effects of low-intensity RFR, in general, 93 confirmed that RFR induces oxidative effects in biological systems. A wide pathogenic potential of the induced ROS and their involvement in cell signaling pathways explains a range of biological/health effects of low-intensity RFR, which include both cancer and non-cancer pathologies. In conclusion, our analysis demonstrates that low-intensity RFR is an expressive oxidative agent for living cells with a high pathogenic potential and that the oxidative stress induced by RFR exposure should be recognized as one of the primary mechanisms of the biological activity of this kind of radiation. PMID:26151230

  2. Dose dependence of acetylcholinesterase activity in neuroblastoma cells exposed to modulated radio-frequency electromagnetic radiation.

    PubMed

    Dutta, S K; Das, K; Ghosh, B; Blackman, C F

    1992-01-01

    Radio-frequency electromagnetic radiation (RFR) at 915 and 147 MHz, when sinusoidally amplitude modulated (AM) at 16 Hz, has been shown to enhance release of calcium ions from neuroblastoma cells in culture. The dose-response relation is unusual, consisting of two power-density "windows" in which enhanced efflux occurs, separated by power-density regions in which no effect is observed. To explore the physiological importance of these findings, we have examined the impact of RFR exposure on a membrane-bound enzyme, acetylcholinesterase (AChE), which is intimately involved with the acetylcholine (ACh) neurotransmitter system. Neuroblastoma cells (NG108), exposed for 30 min to 147-MHz radiation, AM at 16 Hz, demonstrated enhanced AChE activity, as assayed by a procedure using 14C-labeled ACh. Enhanced activity was observed within a time window between 7.0 and 7.5 h after the cells were plated and only when the exposure occurred at power densities identified in a previous report as being effective for altering the release of calcium ions. Thus RFR affects both calcium-ion release and AChE activity in nervous system-derived cells in culture in a common dose-dependent manner. PMID:1510740

  3. Short-duration exposure to radiofrequency electromagnetic radiation alters the chlorophyll fluorescence of duckweeds (Lemna minor).

    PubMed

    Senavirathna, Mudalige Don Hiranya Jayasanka; Takashi, Asaeda; Kimura, Yuichi

    2014-12-01

    Plants growing in natural environments are exposed to radiofrequency electromagnetic radiation (EMR) emitted by various communication network base stations. The environmental concentration of this radiation is increasing rapidly with the congested deployment of base stations. Although numerous scientific studies have been conducted to investigate the effects of EMR on the physiology of humans and animals, there have been few attempts to investigate the effects of EMR on plants. In this study, we attempted to evaluate the effects of EMR on photosynthesis by investigating the chlorophyll fluorescence (ChF) parameters of duckweed fronds. During the experiment, the fronds were tested with 2, 2.5, 3.5, 5.5 and 8 GHz EMR frequencies, which are not widely studied even though there is a potentially large concentration of these frequencies in the environment. The duckweed fronds were exposed to EMR for 30 min, 1 h and 24 h durations with electric field strength of 45-50 V/m for each frequency. The results indicated that exposure to EMR causes a change in the non-photochemical quenching of the duckweeds. The changes varied with the frequency of the EMR and were time-varying within a particular frequency. The temperature remained unchanged in the duckweed fronds upon exposure to EMR, which confirms that the effect is non-thermal. PMID:24131393

  4. Public Exposure from Indoor Radiofrequency Radiation in the City of Hebron, West Bank-Palestine.

    PubMed

    Lahham, Adnan; Sharabati, Afefeh; ALMasri, Hussien

    2015-08-01

    This work presents the results of measured indoor exposure levels to radiofrequency (RF) radiation emitting sources in one of the major cities in the West Bank-the city of Hebron. Investigated RF emitters include FM, TV broadcasting stations, mobile telephony base stations, cordless phones [Digital Enhanced Cordless Telecommunications (DECT)], and wireless local area networks (WLAN). Measurements of power density were conducted in 343 locations representing different site categories in the city. The maximum total power density found at any location was about 2.3 × 10 W m with a corresponding exposure quotient of about 0.01. This value is well below unity, indicating compliance with the guidelines of the International Commission on Non-ionizing Radiation Protection (ICNIRP). The average total exposure from all RF sources was 0.08 × 10 W m. The relative contributions from different sources to the total exposure in terms of exposure quotient were evaluated and found to be 46% from FM radio, 26% from GSM900, 15% from DECT phones, 9% from WLAN, 3% from unknown sources, and 1% from TV broadcasting. RF sources located outdoors contribute about 73% to the population exposure indoors. PMID:26107432

  5. Temperature regulation in the unrestrained rabbit during exposure to 600-MHz radiofrequency radiation

    SciTech Connect

    Gordon, C.J.; Long, M.D.; Fehlner, K.S.

    1986-01-01

    Six male New Zealand white rabbits were individually exposed to 600-MHz radiofrequency (RF) radiation for 90 min in a waveguide exposure system at an ambient temperature (Ta) of 20 or 30 C. Immediately after exposure, the rabbit was removed from the exposure chamber and its colonic and ear skin temperatures were quickly measured. The whole-body specific absorption rate (SAR) required to increase colonic and ear skin temperature was determined. At a Ta of 20 C, the threshold SAR for elevating colonic and ear skin temperature was 0.64 and 0.26 W/kg, respectively. At a Ta of 30 C, the threshold SARs were slightly less than at 20 C, with values of 0.26 W/kg for elevating colonic temperature and 0.19 W/kg for elevating ear skin temperature. The relationship between heat load and elevation in deep body temperature shown in the study at 600 MHz is similar to past studies that employed much-higher frequencies of RF radiation (2450-2884 MHz).

  6. Non-fluoroscopic navigation systems for radiofrequency catheter ablation for supraventricular tachycardia reduce ionising radiation exposure

    PubMed Central

    See, Jason; Amora, Jonah L; Lee, Sheldon; Lim, Paul; Teo, Wee Siong; Tan, Boon Yew; Ho, Kah Leng; Lee, Chee Wan; Ching, Chi Keong

    2016-01-01

    INTRODUCTION The use of non-fluoroscopic systems (NFS) to guide radiofrequency catheter ablation (RFCA) for the treatment of supraventricular tachycardia (SVT) is associated with lower radiation exposure. This study aimed to determine if NFS reduces fluoroscopy time, radiation dose and procedure time. METHODS We prospectively enrolled patients undergoing RFCA for SVT. NFS included EnSite™ NavX™ or CARTO® mapping. We compared procedure and fluoroscopy times, and radiation exposure between NFS and conventional fluoroscopy (CF) cohorts. Procedural success, complications and one-year success rates were reported. RESULTS A total of 200 patients over 27 months were included and RFCA was guided by NFS for 79 patients; those with atrioventricular nodal reentrant tachycardia (AVNRT), left-sided atrioventricular reentrant tachycardia (AVRT) and right-sided AVRT were included (n = 101, 63 and 36, respectively). Fluoroscopy times were significantly lower with NFS than with CF (10.8 ± 11.1 minutes vs. 32.0 ± 27.5 minutes; p < 0.001). The mean fluoroscopic dose area product was also significantly reduced with NFS (NSF: 5,382 ± 5,768 mGy*cm2 vs. CF: 21,070 ± 23,311 mGy*cm2; p < 0.001); for all SVT subtypes. There was no significant reduction in procedure time, except for left-sided AVRT ablation (NFS: 79.2 minutes vs. CF: 116.4 minutes; p = 0.001). Procedural success rates were comparable (NFS: 97.5% vs. CF: 98.3%) and at one-year follow-up, there was no significant difference in the recurrence rates (NFS: 5.2% vs. CF: 4.2%). No clinically significant complications were observed in both groups. CONCLUSION The use of NFS for RFCA for SVT is safe, with significantly reduced radiation dose and fluoroscopy time. PMID:26805664

  7. Influence of electromagnetic radiation on the power balance in a radiofrequency microdischarge with a hollow needle electrode

    SciTech Connect

    Despax, B.; Pascal, O.; Gherardi, N.; Naude, N.; Belinger, A.; Pitchford, L. C.

    2012-10-01

    This study is focused on the power deposition in microplasma jet discharges generated by application of radiofrequency (RF) excitation to a hollow needle electrode. The plasma jet is initiated at atmospheric pressure in open air with a flow of helium through the electrode. We show that in this configuration, a significant part of the injected power is dissipated in electromagnetic radiation. Many recent works have demonstrated the potential of either cold plasma jets or of RF radiation for applications in medicine, and therefore a source that produces both a cold plasma jet and RF radiation could be of interest.

  8. Effects of GSM modulated radio-frequency electromagnetic radiation on permeability of blood-brain barrier in male & female rats.

    PubMed

    Sırav, Bahriye; Seyhan, Nesrin

    2016-09-01

    With the increased use of mobile phones, their biological and health effects have become more important. Usage of mobile phones near the head increases the possibility of effects on brain tissue. This study was designed to investigate the possible effects of pulse modulated 900MHz and 1800MHz radio-frequency radiation on the permeability of blood-brain barrier of rats. Study was performed with 6 groups of young adult male and female wistar albino rats. The permeability of blood-brain barrier to intravenously injected evans blue dye was quantitatively examined for both control and radio-frequency radiarion exposed groups. For male groups; Evans blue content in the whole brain was found to be 0.08±0.01mg% in the control, 0.13±0.03mg% in 900MHz exposed and 0.26±0.05mg% in 1800MHz exposed animals. In both male radio-frequency radiation exposed groups, the permeability of blood-brain barrier found to be increased with respect to the controls (p<0.01). 1800MHz pulse modulated radio-frequency radiation exposure was found more effective on the male animals (p<0.01). For female groups; dye contents in the whole brains were 0.14±0.01mg% in the control, 0.24±0.03mg% in 900MHz exposed and 0.14±0.02mg% in 1800MHz exposed animals. No statistical variance found between the control and 1800MHz exposed animals (p>0.01). However 900MHz pulse modulated radio-frequency exposure was found effective on the permeability of blood-brain barrier of female animals. Results have shown that 20min pulse modulated radio-frequency radiation exposure of 900MHz and 1800MHz induces an effect and increases the permeability of blood-brain barrier of male rats. For females, 900MHz was found effective and it could be concluded that this result may due to the physiological differences between female and male animals. The results of this study suggest that mobile phone radation could lead to increase the permeability of blood-brain barrier under non-thermal exposure levels. More studies are needed

  9. Effects of simultaneous radiofrequency radiation and chemical exposure of mammalian cells. Volume 1. Annual report, 2 January-31 December 1984

    SciTech Connect

    Meltz, M.L.

    1987-08-01

    The major objective of this project was to determine whether radiofrequency radiation (RFR), at power densities and specific absorption rate (SAR) values which can result in temperature increases in the exposure medium, can affect the extent of chemically induced toxicity, mutagenicity, sister chromatid exchange, or chromosome aberrations in mammalian cells. The in-vitro system used for toxicity and mutagenicity studies is the mouse leukemic L5178Y cell thymidine kinase locus mutation assay.

  10. Radiation exposure to operator and patients during cardiac electrophysiology study, radiofrequency catheter ablation and cardiac device implantation procedures

    NASA Astrophysics Data System (ADS)

    Lee, C. H.; Cho, J. H.; Park, S. J.; Kim, J. S.; On, Y. K.; Huh, J.

    2015-10-01

    The purpose of this study was to measure the radiation exposure to operator and patient during cardiac electrophysiology study, radiofrequency catheter ablation and cardiac device implantation procedures and to calculate the allowable number of cases per year. We carried out 9 electrophysiology studies, 40 radiofrequency catheter ablation and 11 cardiac device implantation procedures. To measure occupational radiation dose and dose-area product (DAP), 13 photoluminescence glass dosimeters were placed at eyes (inside and outside lead glass), thyroids (inside and outside thyroid collar), chest (inside and outside lead apron), wrists, genital of the operator (inside lead apron), and 6 of photoluminescence glass dosimeters were placed at eyes, thyroids, chest and genital of the patient. Exposure time and DAP values were 11.7 ± 11.8 min and 23.2 ± 26.2 Gy cm2 for electrophysiology study; 36.5 ± 42.1 min and 822.4 ± 125.5 Gy cm2 for radiofrequency catheter ablation; 16.2 ± 9.3 min and 27.8 ± 16.5 Gy cm2 for cardiac device implantation procedure, prospectively. 4591 electrophysiology studies can be conducted within the occupational exposure limit for the eyes (150 mSv), and 658-electrophysiology studies with radiofrequency catheter ablation can be carried out within the occupational exposure limit for the hands (500 mSv). 1654 cardiac device implantation procedure can be conducted within the occupational exposure limit for the eyes (150 mSv). The amounts of the operator and patient's radiation exposure were comparatively small. So, electrophysiology study, radio frequency catheter ablation and cardiac device implantation procedures are safe when performed with modern equipment and optimized protective radiation protect equipment.

  11. Acoustic radiation force impulse elastography for hepatocellular carcinoma-associated radiofrequency ablation

    PubMed Central

    Kwon, Hee-Jin; Kang, Myong-Jin; Cho, Jin-Han; Oh, Jong-Young; Nam, Kyung-Jin; Han, Sang-Yeong; Lee, Sung Wook

    2011-01-01

    AIM: To evaluate the potential usefulness of acoustic radiation force impulse (ARFI) images for evaluation of hepatocellular carcinomas (HCC)-associated radiofrequency ablation. METHODS: From January 2010 to June 2010, a total of 38 patients with HCC including recurred HCCs after RFA underwent ARFI elastography. The brightness of tumor was checked and the shear wave velocity was measured for the quantification of stiffness. According to the brightness, the tumors were classified as brighter, same color and darker compared with adjacent parenchyma. Using the same methods, 8 patients with recurred HCCs after RFA state were evaluated about the brightness compared with adjacent RFA ablation area. RESULTS: In the 38 patients with HCCs, 20 (52.6%) were brighter than surrounding cirrhotic parenchyma. Another 13 (34.2%) were darker. The others (5 cases, 13.2%) were seen as the same color as the adjacent liver parenchyma. Post-RFA lesions were darker than previous tumor and surrounding parenchyma in all 38 cases. However, recurred HCCs were brighter than the treated site in all 8 cases. CONCLUSION: Using ARFI technique is helpful for differential diagnosis in order to detect recurred HCCs more easily in patients with confusing status. PMID:21528062

  12. Cognitive effects of cellular phones: a possible role of non-radiofrequency radiation factors.

    PubMed

    Hareuveny, Ronen; Eliyahu, Ilan; Luria, Roy; Meiran, Nachshon; Margaliot, Menachem

    2011-10-01

    Some studies found that cognitive functions of human beings may be altered while exposed to radiofrequency radiation (RFR) emitted by cellular phones. In two recent studies, we have found that experiment duration and exposure side (i.e., phone's location--right or left) may have a major influence on the detection of such effects. In this brief follow-up experiment, 29 right-handed male subjects were divided into two groups. Each subject had two standard cellular phones attached to both sides of his head. The subjects performed a spatial working memory task that required either a left-hand or a right-hand response under one of the two exposure conditions: left side of the head or right side. Contrary to our previous studies, in this work external antennas located far away from the subjects were connected to the cellular phones. This setup prevents any emission of RFR from the internal antenna, thus drastically reducing RFR exposure. Despite that, the results remain similar to those obtained in our previous work. These results indicate that some of the effects previously attributed to RFR can be the result of some confounders. PMID:21488064

  13. Effect of radiofrequency radiation on MRNA expression in cultured rodent cells

    SciTech Connect

    Parker, J.E.; Kiel, J.L.; Winters, W.D.

    1988-01-01

    Radiofrequency radiation (RFR) has been reported to induce adverse effects in biological systems, such as teratogenic and embryo lethal effects in mammals particularly during exposures producing significant hyperthermia. Other studies have implicated microwave exposure with causing changes in chromosome number and structure, formation of cataracts in humans rabbits and dogs; and promoting malignant tumor formation in rats, as well as increasing tumor production and leukemias. In addition, microwave exposures have been reported to change the structure of purified double-stranded plasmid DNA, causing it to become nicked and increasing the proportion of relaxed to super coiled molecules. In view of these reports of changes at different levels of cellular function and structure of mammalian systems to microwaves, the authors asked themselves if changes at the level of mRNA expression could be detected after microwave exposure of cultured rodent cells. They chose to look at the mRNA expression of certain oncogenes known to show elevated levels during cell replication, at the heat shock proteins known to respond to stresses other than heat, and at the long terminal repeat (LTR) region of mouse mammary tumor virus in four rodent cell lines.

  14. Normalizing the thermal effects of radiofrequency radiation: body mass versus total body surface area

    SciTech Connect

    Gordon, C.J.

    1987-01-01

    The current guideline for exposure to radiofrequency radiation (RFR) was developed through assessment of the biological effects data collected primarily from the rat. The consensus that a lack of hazardous biological effects occurred below a whole-body-averaged specific absorption rate (SAR) of 4.0 W/kg led to the proposition of a 0.4 W/kg guideline with a built-in safety factor of 10. This paper demonstrates that if the RFR absorption rate in the rat had been normalized with respect to total body surface area rather than body mass, the exposure guideline would be 2.3 W/m2, which translates to an SAR of approximately 0.06 W/kg for an adult human. It is further shown that a given RFR absorption rate, normalized as a fraction of a species' heat loss per unit of surface area, is independent of body mass over a range of 0.03-100 kg; however, a normalization of the RFR absorption rate to heat loss per unit of body mass is highly dependent on the species' mass. Normalizing the rate of RFR absorption to the surface area of the rat indicates that the current RFR exposure guideline of 0.4 W/kg may be too high.

  15. Thermal responses to 5. 6-GHz radiofrequency radiation in anesthetized rats. Effect of chlorpromazine

    SciTech Connect

    Jauchem, J.R.; Frei, M.R.; Heinmets, F.

    1988-01-01

    Anesthetized rats were exposed to 5.6-GHz continuous-wave radiofrequency radiation (RFR) at an average power density of 60 mW/Sq. cm (average specific absorption rate 12 W/kg). Exposure was performed to raise colonic temperature from 38.5 to 39.5C. Following acute administration of chlorpromazine, body temperature exhibited a faster return to baseline temperature when exposure was discontinued. When exposure was initiated at 38.5C and continued until lethal temperature resulted, chlorpromazine-treated animals exhibited significantly shorter survival times than saline-treated animals. Thus, although chlorpromazine enhanced thermoregulatory efficiency at colonic temperature below 39.5 deg C, the drug caused increased susceptibility to terminal RFR. The present results, when compared with previous studies of irradiation at 2.8 GHz, indicate that the effects of chlorpromazine on thermal response to RFR during intermittent and terminal exposure are similar at both 2.8 and 5.6 GHz.

  16. Radio-frequency radiation exposure from AM radio transmitters and childhood leukemia and brain cancer.

    PubMed

    Ha, Mina; Im, Hyoungjune; Lee, Mihye; Kim, Hyun Joo; Kim, Byung-Chan; Gimm, Yoon-Myoung; Pack, Jeong-Ki

    2007-08-01

    Leukemia and brain cancer patients under age 15 years, along with controls with respiratory illnesses who were matched to cases on age, sex, and year of diagnosis (1993-1999), were selected from 14 South Korean hospitals using the South Korean Medical Insurance Data System. Diagnoses were confirmed through the South Korean National Cancer Registry. Residential addresses were obtained from medical records. A newly developed prediction program incorporating a geographic information system that was modified by the results of actual measurements was used to estimate radio-frequency radiation (RFR) exposure from 31 amplitude modulation (AM) radio transmitters with a power of 20 kW or more. A total of 1,928 leukemia patients, 956 brain cancer patients, and 3,082 controls were analyzed. Cancer risks were estimated using conditional logistic regression adjusted for residential area, socioeconomic status, and community population density. The odds ratio for all types of leukemia was 2.15 (95% confidence interval (CI): 1.00, 4.67) among children who resided within 2 km of the nearest AM radio transmitter as compared with those resided more than 20 km from it. For total RFR exposure from all transmitters, odds ratios for lymphocytic leukemia were 1.39 (95% CI: 1.04, 1.86) and 1.59 (95% CI: 1.19, 2.11) for children in the second and third quartiles, respectively, versus the lowest quartile. Brain cancer and infantile cancer were not associated with AM RFR. PMID:17556764

  17. Most cancer in firefighters is due to radio-frequency radiation exposure not inhaled carcinogens.

    PubMed

    Milham, S

    2009-11-01

    Recent reviews and reports of cancer incidence and mortality in firefighters conclude that they are at an increased risk of a number of cancers. These include leukemia, multiple myeloma, non-Hodgkin's lymphoma, male breast cancer, malignant melanoma, and cancers of the brain, stomach, colon, rectum, prostate, urinary bladder, testes, and thyroid. Firefighters are exposed to a long list of recognized or probable carcinogens in combustion products and the presumed route of exposure to these carcinogens is by inhalation. Curiously, respiratory system cancers and diseases are usually not increased in firefighters as they are in workers exposed to known inhaled carcinogens. The list of cancers with increased risk in firefighters strongly overlaps the list of cancers at increased risk in workers exposed to electromagnetic fields (EMF) and radiofrequency radiation (RFR). Firefighters have increased exposure to RFR in the course of their work, from the mobile two-way radio communications devices which they routinely use while fighting fires, and at times from firehouse and fire vehicle radio transmitters. I suggest that some of the increased cancer risk in firefighters is caused by RFR exposure, and is therefore preventable. The precautionary principle should be applied to reduce the risk of cancer in firefighters, and workman's compensation rules will necessarily need to be modified. PMID:19464814

  18. Naltrexone-sensitive analgesia following exposure of mice to 2450-MHz radiofrequency radiation.

    PubMed

    Maillefer, R H; Quock, R M

    1992-09-01

    To determine whether exposure to radiofrequency radiation (RFR) would induce sufficient thermal stress to activate endogenous opioid mechanisms, male Swiss Webster mice were exposed to 10, 15, and 20 mW/cm2 RFR in a 2450-MHz waveguide system for 10 min at specific absorption rates (SARs) of 23.7, 34.6, and 45.5 W/kg, respectively, then tested in the abdominal constriction paradigm. Confinement in the RFR exposure chamber alone did not appreciably alter body temperature but did appear to induce a stress-associated analgesia that was not blocked by naltrexone. Exposure of confined mice to RFR raised body temperature and further increased analgesia in an SAR-dependent manner. The high SAR-induced analgesia, but not the hyperthermia, was blocked by naltrexone. These findings suggest that 1) RFR produces SAR-dependent hyperthermia and analgesia, and 2) RFR-induced analgesia is mediated by opioid mechanisms while confinement-induced analgesia involves nonopioid mechanisms. PMID:1409913

  19. Thermoregulatory responses of rats exposed to 9. 3-GHz radio-frequency radiation

    SciTech Connect

    Frei, M.R.; Jauchem, J.R.; Heinmets, F.

    1987-10-15

    Ketamine-anesthetized Sprague-Dawley rats were exposed in H orientation to far-field 9.3-GHz continuous-wave (CW) and pulsed (2 microseconds 500 pps) radiofrequency radiation (RFR) at average power densities of 30 and 60 mW/sq. cm (whole-body average specific absorption rates of 9.3 and 18.6 W/kg, respectively). Irradiation was conducted to cyclicly increase colonic temperature from 38.5 to 39.5 C. Colonic, tympanic, and subcutaneous temperatures, ECG, blood pressure, and respiratory rate were continuously recorded during experimentation. At both power densities, the subcutaneous and tympanic temperature increases significantly exceeded the colonic temperature increase. At both exposure levels, heart rate increased significantly during irradiation and returned to baseline when exposure was discontinued. Blood pressure and respiratory rate did not significantly change during irradiation. There were no significant differences between the effects of CW and pulsed RFR exposure. The levels of subcutaneous heating and heart rate change were greater, and the times required to achieve and to recover from a 1 C colonic temperature increase were longer than in previous studies conducted at 2.8 GHz. Results of these studies indicate that the carrier frequency used during irradiation markedly affects the pattern of heat distribution and the physiological responses of RF-irradiated animals.

  20. Radiofrequency radiation alters the immune system. II. Modulation of in vivo lymphocyte circulation

    SciTech Connect

    Liburdy, R.P.

    1980-07-01

    In vivo lymphocyte circulation was significantly altered in mice exposed to whole-body radiofrequency radiation (RFR). In vivo lymphocyte circulation was followed by quantitating activity of sodium chromate-51-labeled lymphocytes in the lung, spleen, liver, and bone marrow of animals at different times after iv spleen lymphocyte injection. Immediately after cell injection, animals were exposed to 2.6-GHz RFR (CW) at 25 or 5 mW/cm/sup 2/ (3.8 W/kg) for 1 h. At 1,6, and 24 h aftr lymphocyte injection target organs were removed, weighed, and counted. Sham RFR, warm-air, and steroid-treated groups were included as controls. Hyperthermic RFR exposure (25 mW/cm/sup 2/, 2.0/sup 0/C increase in core temperature) led to a 37% reduction in lymphocytes leaving the lung to migrate into the spleen. In addition, a threefold increse in spleen lymphocytes entering the bone marrow occurred. Significantly, this pattern was also observed in the steroid-treated group; nonthermogenic RFR exposure (5 mWcm/sup 2/) and warm-air exposures did not lead to altered lymphocyte traffic. These results support the idea that steroid release associated with thermal stress and the process of thermoregulation is a significant operatnt factor responsible for RFR effects on the immune system.

  1. Body temperature in the mouse, hamster, and rat exposed to radiofrequency radiation: an interspecies comparison

    SciTech Connect

    Gordon, C.J.; Long, M.D.; Fehlner, K.S.; Stead, A.G.

    1986-01-01

    Colonic temperatures of BALB/c and CBA/J mice, golden hamsters, and Sprague-Dawley rats were taken immediately after exposure for 90 min to radiofrequency (RF) radiation. Exposures were made in 2450 MHz (mouse and hamster) or 600-MHz (rat) waveguide exposure systems while the dose rate, to specific adsorption rate (SAR), was continuously recorded. Experiments were performed on naive, unrestrained animals at ambient temperatures (Ta) of 20 and 30 C. Body mass and Ta were found to be significant factors in influencing the threshold SAR for the elevation of colonic temperature. The threshold SARs at Ta's of 20 and 30 C were, respectively: 27.5 and 12.1 W/kg for the BALB/c mouse; 40.7 and 8.5 W/kg for the CBA/J mouse; 8.7 and 0.61 W/kg for the golden hamster; and 1.58 and 0.4 W/kg for the Sprague-Dawley rat.

  2. Radio-frequency excitation of harmonic microwave radiation from a Penning reflex discharge

    SciTech Connect

    Tate, J.P.; Wharton, C.B. )

    1993-04-01

    Experimental results on multiple-harmonic emission at 8.8 GHz from a Penning reflex discharge (PRD) are reported. Observations of the frequency spectra of microwave emission showed copius harmonic generation of frequencies having two completely different origins: (1) spontaneously excited high harmonics of the electron cyclotron frequency and (2) high harmonics of the frequency of an injected signal independent of the magnetic field strength, a phenomenon reported here for the first time. For spontaneous harmonic emission there was a current threshold, whose magnitude depended on gas pressure and magnetic field strength. When a signal was injected, however, high harmonics (up to the 18th) could be seen at discharge currents well below this threshold value. Comparisons between the two types of radiation are made and discussion of possible mechanisms is provided. It is concluded that the coupling efficiency of the radio-frequency (rf)-excited emission is dependent on the relationship between the rf drive frequency and the electron cyclotron frequency. Finite Larmor radius effects may also influence this coupling. The plasma sheath size will also be a factor in the transfer of energy from the probe to the bulk plasma. Results which seek to elucidate these effects are presented.

  3. Effects of 20-MHz radiofrequency radiation on rat hematology splenic function, and serum chemistry

    SciTech Connect

    Wong, L.S.; Merritt, J.H.; Kiel, J.L.

    1985-08-01

    In this study, Sprague-Dawley rats were exposed in a TEM chamber to 20-MHz (HF-band) continuous-wave radiofrequency radiation (RFR) for 6 hr/days, 5 days/week up to 6 weeks. Randomly sampled rats killed on Days 8, 22, 39, and 42 after initiation of exposure showed no statistically significant difference from controls for body mass, spleen cell density, erythrocyte and leukocyte counts, hematocrit, hemoglobin, methemoglobin, erythrocyte fragility, bilirubin, creatinine, SGPT, alkaline phosphatase, calcium, sodium, potassium, and spleen cell chemiluminescence. Splenic mass differences were statistically significant only on Day 22. Spleen to body mass ratios differed significantly between exposed and control groups on Days 22 and 39. Histologic examination of the rats revealed the successive accumulation of phagocytic cells, lymphoid proliferation, development of lesions, and tissue necrosis characteristic of respiratory mycoplasmosis. In a followup experiment, a separate set of rats was exposed for 6 weeks to identical levels of RFR. No significant differences were found in splenic parameters and spleen cell peroxidative activity. Histologic examination of these animals revealed no evidence of mycoplasma infection. The observed differences between exposed and control animals of the first experiment appear to have resulted from subclinical respiratory mycoplasmosis rather than exposure to RFR.

  4. Radiated radiofrequency immunity testing of automated external defibrillators - modifications of applicable standards are needed

    PubMed Central

    2011-01-01

    Background We studied the worst-case radiated radiofrequency (RF) susceptibility of automated external defibrillators (AEDs) based on the electromagnetic compatibility (EMC) requirements of a current standard for cardiac defibrillators, IEC 60601-2-4. Square wave modulation was used to mimic cardiac physiological frequencies of 1 - 3 Hz. Deviations from the IEC standard were a lower frequency limit of 30 MHz to explore frequencies where the patient-connected leads could resonate. Also testing up to 20 V/m was performed. We tested AEDs with ventricular fibrillation (V-Fib) and normal sinus rhythm signals on the patient leads to enable testing for false negatives (inappropriate "no shock advised" by the AED). Methods We performed radiated exposures in a 10 meter anechoic chamber using two broadband antennas to generate E fields in the 30 - 2500 MHz frequency range at 1% frequency steps. An AED patient simulator was housed in a shielded box and delivered normal and fibrillation waveforms to the AED's patient leads. We developed a technique to screen ECG waveforms stored in each AED for electromagnetic interference at all frequencies without waiting for the long cycle times between analyses (normally 20 to over 200 s). Results Five of the seven AEDs tested were susceptible to RF interference, primarily at frequencies below 80 MHz. Some induced errors could cause AEDs to malfunction and effectively inhibit operator prompts to deliver a shock to a patient experiencing lethal fibrillation. Failures occurred in some AEDs exposed to E fields between 3 V/m and 20 V/m, in the 38 - 50 MHz range. These occurred when the patient simulator was delivering a V-Fib waveform to the AED. Also, we found it is not possible to test modern battery-only-operated AEDs for EMI using a patient simulator if the IEC 60601-2-4 defibrillator standard's simulated patient load is used. Conclusions AEDs experienced potentially life-threatening false-negative failures from radiated RF, primarily

  5. Effects of radiofrequency radiation exposure on blood-brain barrier permeability in male and female rats.

    PubMed

    Sirav, Bahriye; Seyhan, Nesrin

    2011-12-01

    During the last several decades, numerous studies have been performed aiming at the question of whether or not exposure to radiofrequency radiation (RFR) influences the permeability of the blood-brain barrier (BBB). The objective of this study was to investigate the effect of RFR on the permeability of BBB in male and female Wistar albino rats. Right brain, left brain, cerebellum, and total brain were analyzed separately in the study. Rats were exposed to 0.9 and 1.8 GHz continuous-wave (CW) RFR for 20 min (at SARs of 4.26 mW/kg and 1.46 mW/kg, respectively) while under anesthesia. Control rats were sham-exposed. Disruption of BBB integrity was detected spectrophotometrically using the Evans-blue dye, which has been used as a BBB tracer and is known to be bound to serum albumin. Right brain, left brain, cerebellum, and total brain were evaluated for BBB permeability. In female rats, no albumin extravasation was found in in the brain after RFR exposure. A significant increase in albumin was found in the brains of the RF-exposed male rats when compared to sham-exposed male brains. These results suggest that exposure to 0.9 and 1.8 GHz CW RFR at levels below the international limits can affect the vascular permeability in the brain of male rats. The possible risk of RFR exposure in humans is a major concern for the society. Thus, this topic should be investigated more thoroughly in the future. PMID:22047463

  6. Radiofrequency (microwave) radiation exposure of mammalian cells during UV-induced DNA repair synthesis

    SciTech Connect

    Meltz, M.L.; Walker, K.A.; Erwin, D.N.

    1987-05-01

    The effect of continuous-wave (CW) and pulsed-wave (PW) radiofrequency radiation (RFR) in the microwave range on UV-induced DNA repair has been investigated in MRC-5 normal human diploid fibroblasts. RFR exposure at power densities of 1 (or 5) and 10 mW/cm2 gave a maximum specific absorption rate (SAR) (at 10 mW/cm2) of 0.39 +/- 0.15 W/kg for 350 MHz RFR, 4.5 +/- 3.0 W/kg for 850 MHz RFR, and 2.7 +/- 1.6 W/kg for 1.2 GHz RFR. RFR exposures for 1 to 3 h at 37 degrees C, in either continuous-wave or pulsed-wave modes, had no effect on the rate of repair replication label incorporated into preexisting UV-damaged DNA. RFR exposures (PW), with a constant medium temperature of 39 degrees C at 350 and 850 MHz during the repair period after UV damage, also had no effect. Assay for induction of repair synthesis by RFR exposure alone in non-UV irradiated cells was negative for the 350-, 850-, and 1200-MHz CW and PW RFR at 37 degrees C and the 350- and 850-MHz PW RFR at 39 degrees C. RFR does not induce DNA repair under these exposure conditions. In preliminary experiments--with the tissue culture medium maintained at 39 degrees C and RFR exposures (PW) at the frequencies of 350, 850, and 1200 MHz--no effect on incorporation of (/sup 3/H)thymidine into DNA undergoing semiconservative synthesis was observed.

  7. Neurodegenerative changes and apoptosis induced by intrauterine and extrauterine exposure of radiofrequency radiation.

    PubMed

    Güler, Göknur; Ozgur, Elcin; Keles, Hikmet; Tomruk, Arin; Vural, Sevil Atalay; Seyhan, Nesrin

    2016-09-01

    Adverse health effects of radiofrequency radiation (RFR) on the ongoing developmental stages of children from conception to childhood are scientifically anticipated subject. This study was performed to identify the effects of global system for mobile communications (GSM) modulated mobile phone like RFR in 1800MHz frequency on oxidative DNA damage and lipid peroxidation beside the apoptotic cell formation, using histopathological and immunohistochemical methods in the brain tissue of 1-month-old male and female New Zealand White rabbits that were exposed to these fields at their mother's womb and after the birth. Oxidative DNA damage and lipid peroxidation levels were investigated by measuring the 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) levels, respectively. Histopathological changes were observed using by hematoxylin and eosin (HE) staining. Apoptotic cells were detected in the examined organs by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. For both male and female infants; 8-OHdG levels increased in the group exposed to RFR in both intrauterine and extrauterine periods compared to the infants that were never exposed to RFR and the ones were exposed when they reached one month of age (p<0.05). MDA results were different for male and female rabbits. There was no difference between all female infant groups (p>0.05), while only intrauterine exposure significantly causes MDA level increase for the male infants. HE staining revealed mild lessions in neuronal necrobiosis in brain tissues of female rabbits that had only intaruterine exposure and male rabbits had only extrauterine exposure. Gliosis were mildly positive in brain tissues of rabbits that are exposed only intrauterine period, also the group exposed both intrauterine and extrauterine periods. However, there was no apoptotic change detected by TUNEL staining in the brain tissues of all groups. PMID:26520616

  8. Radiofrequency electromagnetic radiation exposure inside the metro tube infrastructure in Warszawa.

    PubMed

    Gryz, Krzysztof; Karpowicz, Jolanta

    2015-09-01

    Antennas from various wireless communications systems [e.g. mobile phones base transceiver stations (BTS) and handsets used by passengers, public Internet access, staff radiophone transmitters used between engine-drivers and traffic operators] emitting radiofrequency electromagnetic radiation (RF-EMR) are used inside underground metro public transportation. Frequency-selective exposimetric investigations of RF-EMR exposure inside the metro infrastructure in Warsaw (inside metro cars passing between stations and on platforms) were performed. The statistical parameters of exposure to the E-field were analyzed for each frequency range and for a total value (representing the wide-band result of measurements of complex exposure). The recorded exposimetric profiles showed the dominant RF-EMR sources: handsets and BTS of mobile communication systems (GSM 900 and UMTS 2100) and local wireless Internet access (WiFi 2G). Investigations showed that the GSM 900 system is the dominant source of exposure - BTS (incessantly active) on platforms, and handsets - used by passengers present nearby during the tube drive. The recorded E-field varies between sources (for BTS were: medians - 0.22 V/m and 75th percentile - 0.37 V/m; and for handsets: medians - 0.28 V/m and 75th percentile - 0.47 V/m). Maximum levels (peaks) of exposure recorded from mobile handsets exceeded 10 V/m (upper limit of used exposimeters). Broadband measurements of E-field, including the dominant signal emitted by staff radiophones (151 MHz), showed that the level of this exposure of engine-drivers does not exceed 2.5 V/m. PMID:26444204

  9. Radiofrequency radiation-induced calcium-ion-efflux enhancement from human and other neuroblastoma cells in culture: (Final technical report)

    SciTech Connect

    Dutta, S.K.; Ghosh, B.; Blackman, C.F.

    1988-01-01

    In order to test the generality of radiofrequency-radiation-induced change in alternation of /sup 45/Ca/sup 2/plus// efflux from avian and feline brain tissues, human neuroblastoma cells were exposed to electromagnetic radiation at 147 MHz, amplitude modulated (AM) at 16 Hz, at specific absorption rates (SAR) of 0.1, 0.05, 0.01, 0.005, 0.001, and 0.0005 Wkg. Significant /sup 45/Ca/sup 2/plus// efflux was obtained at SAR values of 0.05 and 0.005 Wkg. Enchanced efflux at 0.05 Wkg peaked at the 13-to-16 Hz and at the 57.5-to-60 Hz modulation ranges. A Chinese hamster-mouse hybrid neuroblastoma was also shown to exhibit enchanced radiation-induced /sup 45/Ca/sup 2/plus// efflux at an SAR of 0.05 Wkg, using 147 MHz, AM at 16 hz. These results confirm that amplitude-modulated radiofrequency radiation can induce response in cells of nervous tissue origin from widely different animal species including humans. The results are also consistent with reports of similar findings in avian and feline brain tissue reported by others and indicate the general nature of the phenomenon. 9 refs., 3 tabs.

  10. Effects of radiation from a radiofrequency identification (RFID) microchip on human cancer cells.

    PubMed

    Lai, Henry C; Chan, Ho Wing; Singh, Narendra P

    2016-03-01

    Purpose Radiofrequency identification (RFID) microchips are used to remotely identify objects, e.g. an animal in which a chip is implanted. A passive RFID microchip absorbs energy from an external source and emits a radiofrequency identification signal which is then decoded by a detector. In the present study, we investigated the effect of the radiofrequency energy emitted by a RFID microchip on human cancer cells. Materials and methods Molt-4 leukemia, BT474 breast cancer, and HepG2 hepatic cancer cells were exposed in vitro to RFID microchip-emitted radiofrequency field for 1 h. Cells were counted before and after exposure. Effects of pretreatment with the spin-trap compound N-tert-butyl-alpha-phenylnitrone or the iron-chelator deferoxamine were also investigated. Results We found that the energy effectively killed/retarded the growth of the three different types of cancer cells, and the effect was blocked by the spin-trap compound or the iron-chelator, whereas an inactive microchip and energy from the external source had no significant effect on the cells. Conclusions Data of the present study suggest that radiofrequency field from the microchip affects cancer cells via the Fenton Reaction. Implantation of RFID microchips in tumors may provide a new method for cancer treatment. PMID:26872622

  11. Exposure to Radiofrequency Radiation Emitted from Common Mobile Phone Jammers Alters the Pattern of Muscle Contractions: an Animal Model Study

    PubMed Central

    Rafati, A.; Rahimi, S.; Talebi, A.; Soleimani, A.; Haghani, M.; Mortazavi, S. M. J.

    2015-01-01

    Introduction The rapid growth of wireless communication technologies has caused public concerns regarding the biological effects of electromagnetic radiations on human health. Some early reports indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians such as the alterations of the pattern of muscle extractions. This study is aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted from mobile phone jammers on the pulse height of contractions, the time interval between two subsequent contractions and the latency period of frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz). Materials and Methods Frogs were kept in plastic containers in a room. Animals in the jammer group were exposed to radiofrequency (RF) radiation emitted from a common Jammer at a distance of 1m from the jammer’s antenna for 2 hours while the control frogs were only sham exposed. Then animals were sacrificed and isolated gastrocnemius muscles were exposed to on/off jammer radiation for 3 subsequent 10 minute intervals. Isolated gastrocnemius muscles were attached to the force transducer with a string. Using a PowerLab device (26-T), the pattern of muscular contractions was monitored after applying single square pulses of 1V (1 Hz) as stimuli. Results The findings of this study showed that the pulse height of muscle contractions could not be affected by the exposure to electromagnetic fields. However, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions. PMID:26396969

  12. Chronic exposure of cancer-prone mice to low-level 2450 MHz radiofrequency radiation.

    PubMed

    Frei, M R; Berger, R E; Dusch, S J; Guel, V; Jauchem, J R; Merritt, J H; Stedham, M A

    1998-01-01

    The purpose of this study was to determine whether chronic, low-level exposure of mammary-tumor-prone mice to 2450 MHz radiofrequency radiation (RFR) promotes an earlier onset (decreased latency), a greater total incidence, or a faster growth rate of mammary tumors. One hundred C3H/ HeJ mice were exposed in circularly polarized waveguides (CWG) for 18 months (20 h/day, 7 days/wk) to continuous-wave, 2450 MHz RFR at a whole body average specific absorption rate (SAR) of 0.3 W/kg; 100 mice were sham exposed. Before exposure, SARs were determined calorimetrically; during experimentation, SARs were monitored by differential power measurement. All animals were visually inspected twice daily and were removed from the CWG cages for a weekly inspection, palpation, and weighing. From the time of detection, tumor size was measured weekly. Animals that died spontaneously, became moribund, or were killed after 18 months of exposure were completely necropsied; tissues were fixed and subjected to histopathological evaluations. Results showed no significant difference in weight profiles between sham-irradiated and irradiated mice. Concerning mammary carcinomas, there was no significant difference between groups with respect to palpated tumor incidence (sham = 52%; irradiated = 44%), latency to tumor onset (sham = 62.3 +/- 1.2 wk; irradiated = 64.0 +/- 1.6 wk), and rate of tumor growth. In general, histopathological examination revealed no significant differences in numbers of malignant, metastatic, or benign neoplasms between the two groups; a significantly greater incidence of alveolar-bronchiolar adenoma in the sham-irradiated mice was the only exception. In addition, survival analysis showed no significant difference in cumulative percent survival between sham and irradiated animals. Thus, results indicate that under the conditions of this study, long-term, low-level exposure of mammary-tumor-prone mice to 2450 MHz RFR did not affect mammary tumor incidence, latency to tumor

  13. Fetal radiofrequency radiation exposure from 800-1900 mhz-rated cellular telephones affects neurodevelopment and behavior in mice.

    PubMed

    Aldad, Tamir S; Gan, Geliang; Gao, Xiao-Bing; Taylor, Hugh S

    2012-01-01

    Neurobehavioral disorders are increasingly prevalent in children, however their etiology is not well understood. An association between prenatal cellular telephone use and hyperactivity in children has been postulated, yet the direct effects of radiofrequency radiation exposure on neurodevelopment remain unknown. Here we used a mouse model to demonstrate that in-utero radiofrequency exposure from cellular telephones does affect adult behavior. Mice exposed in-utero were hyperactive and had impaired memory as determined using the object recognition, light/dark box and step-down assays. Whole cell patch clamp recordings of miniature excitatory postsynaptic currents (mEPSCs) revealed that these behavioral changes were due to altered neuronal developmental programming. Exposed mice had dose-responsive impaired glutamatergic synaptic transmission onto layer V pyramidal neurons of the prefrontal cortex. We present the first experimental evidence of neuropathology due to in-utero cellular telephone radiation. Further experiments are needed in humans or non-human primates to determine the risk of exposure during pregnancy. PMID:22428084

  14. Influence of radiofrequency radiation on chromosome aberrations in CHO cells and its interaction with DNA-damaging agents.

    PubMed

    Kerbacher, J J; Meltz, M L; Erwin, D N

    1990-09-01

    A limited number of contradictory reports have appeared in the literature about the ability of radiofrequency (rf) radiation to induce chromosome aberrations in different biological systems. The technical documentation associated with such reports is often absent or deficient. In addition, no information is available as to whether any additional genotoxic hazard would result from a simultaneous exposure of mammalian cells to rf radiation and a chemical which (by itself) induces chromosome aberrations. In the work described, we have therefore tested two hypotheses. The first is that rf radiation by itself, at power densities and exposure conditions which are higher than is consistent with accepted safety guidelines, can induce chromosome aberrations in mammalian cells. The second is that, during a simultaneous exposure to a chemical known to be genotoxic, rf radiation can affect molecules, biochemical processes, or cellular organelles, and thus result in an increase or decrease in chromosome aberrations. Mitomycin C (MMC) and Adriamycin (ADR) were selected because they act by different mechanisms, and because they might put normal cells at risk during combined-modality rf radiation (hyperthermia)-chemotherapy treatment of cancer. The studies were performed with suitable 37 degrees C and equivalent convection heating-temperature controls in a manner designed to discriminate between any thermal and possible nonthermal action. Radiofrequency exposures were conducted for 2 h under conditions resulting in measurable heating (a maximum increase of 3.2 degrees C), with pulsed-wave rf radiation at a frequency of 2450 MHz and an average net forward power of 600 W, resulting in an SAR of 33.8 W/kg. Treatments with MMC or ADR were for a total of 2.5 h and encompassed the 2-h rf radiation exposure period. The CHO cells from each of the conditions were subsequently analyzed for chromosome aberrations. In cells exposed to rf radiation alone, and where a maximum temperature of

  15. Mitogen responsiveness after exposure of influenza virus-infected human mononuclear leukocytes to continuous or pulse-modulated radiofrequency radiation

    SciTech Connect

    Roberts, N.J. Jr.; Michaelson, S.M.; Lu, S.T.

    1987-06-01

    Data are available regarding interactions of radiofrequency radiation (RFR) with normal human mononuclear leukocytes. However, no data have emerged regarding effects of RFR on human leukocytes already challenged by a commonly encountered alternate agent, such as a virus. Therefore, in these studies, uninfected (control) and in vitro influenza virus-infected human mononuclear leukocytes were exposed to 2450 MHz RFR as continuous waves or pulse-modulated at 60 or 16 Hz, at a specific absorption rate of 4 mW/ml. Such exposures produced no significant effects on leukocyte viability or on mitogen-stimulated DNA synthesis by either uninfected or influenza virus-infected leukocytes when compared to sham-RFR-exposed of cells.

  16. Cardiovascular changes in unanesthetized and ketamine-anesthetized Sprague-Dawley rats exposed to 2. 8-GHz radiofrequency radiation

    SciTech Connect

    Jauchem, J.R.; Frei, M.R. )

    1991-01-01

    Sprague-Dawley rats were exposed to 2.8-GHz radiofrequency radiation, first while unanesthetized and then while anesthetized with ketamine (150 mg/kg.I.M.). Irradiation at a power density of 60 mW/cm2 (whole-body average specific absorption rate of approximately 14 W/kg) was conducted for sufficient duration to increase colonic temperature from 38.5 to 39.5 degrees C. The time required for the temperature increase was significantly longer in the anesthetized state. During irradiation, heart rate increased significantly both with and without anesthesia, while mean arterial blood pressure increased only when the rats were unanesthetized. The heart rate increase in the anesthetized state contrasts with a lack of change in a previous study of Fischer rats. This difference between anesthetized Sprague-Dawley and Fischer rats should be considered when comparing cardiovascular data obtained from these two strains of rats.

  17. 2-Methoxyethanol metabolism, embryonic distribution, and macromolecular adduct formation in the rat: the effect of radiofrequency radiation-induced hyperthermia.

    PubMed

    Cheever, K L; Swearengin, T F; Edwards, R M; Nelson, B K; Werren, D W; Conover, D L; DeBord, D G

    2001-05-31

    Exposure of pregnant rats to the solvent 2-methoxyethanol (2ME) and radiofrequency (RF) radiation results in greater than additive fetal malformations (Nelson, B.K., Conover, D.L., Brightwell, W.S., Shaw, P.B., Werren, D.W., Edwards, R.M., Lary, J.M., 1991. Marked increase in the teratogenicity of the combined administration of the industrial solvent 2-methoxyethanol and radiofrequency radiation in rats. Teratology 43, 621-34; Nelson, B.K., Conover, D.L., Shaw, P.B., Werren, D.W., Edwards, R.M., Hoberman, A.M., 1994. Interactive developmental toxicity of radiofrequency radiation and 2-methoxyethanol in rats. Teratology 50, 275-93). The current study evaluated the metabolism of 14C-labeled 2ME and the distribution of methoxyacetic acid (MAA) in maternal and embryonic tissues of pregnant Sprague-Dawley rats either exposed to 10 MHz RF radiation or sham conditions. Additionally, adduct formation for both plasma and embryonic protein was tested as a possible biomarker for the observed 2ME/RF teratogenicity. Rats were administered [ethanol-1,2-(14)C]-2ME (150 mg/kg, 161 microCi/rat average) by gavage on gestation day 13 immediately before RF radiation sufficient to elevate body temperature to 42 degrees C for 30 min. Concurrent sham- and RF-exposed rats were sacrificed at 3, 6, 24 or 48 h for harvest of maternal blood, urine, embryos and extra-embryonic fluid. Tissues were either digested for determination of radioactivity or deproteinized with TCA and analyzed by HPLC for quantification of 2ME metabolites. Results show the presence of 2ME and seven metabolites, with the major metabolite, MAA, peaking at 6 h in the tissues tested. MAA, the proximal teratogen, was detectable in maternal serum, urine, embryo and extraembryonic fluid 48 h after dosing. Clearance of total body 14C was significantly reduced for the RF-exposed animals (P<0.05) for the 24-48 h period, but MAA values for serum, embryos and extraembryonic fluid were similar for both sham- and RF-exposed rats

  18. Electromagnetic noise inhibits radiofrequency radiation-induced DNA damage and reactive oxygen species increase in human lens epithelial cells

    PubMed Central

    Wu, Wei; Wang, KaiJun; Ni, Shuang; Ye, PanPan; Yu, YiBo; Ye, Juan; Sun, LiXia

    2008-01-01

    Purpose The goal of this study was to investigate whether superposing of electromagnetic noise could block or attenuate DNA damage and intracellular reactive oxygen species (ROS) increase of cultured human lens epithelial cells (HLECs) induced by acute exposure to 1.8 GHz radiofrequency field (RF) of the Global System for Mobile Communications (GSM). Methods An sXc-1800 RF exposure system was used to produce a GSM signal at 1.8 GHz (217 Hz amplitude-modulated) with the specific absorption rate (SAR) of 1, 2, 3, and 4 W/kg. After 2 h of intermittent exposure, the ROS level was assessed by the fluorescent probe, 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). DNA damage to HLECs was examined by alkaline comet assay and the phosphorylated form of histone variant H2AX (γH2AX) foci formation assay. Results After exposure to 1.8 GHz RF for 2 h, HLECs exhibited significant intracellular ROS increase in the 2, 3, and 4 W/kg groups. RF radiation at the SAR of 3 W/kg and 4 W/kg could induce significant DNA damage, examined by alkaline comet assay, which was used to detect mainly single strand breaks (SSBs), while no statistical difference in double strand breaks (DSBs), evaluated by γH2AX foci, was found between RF exposure (SAR: 3 and 4 W/kg) and sham exposure groups. When RF was superposed with 2 μT electromagnetic noise could block RF-induced ROS increase and DNA damage. Conclusions DNA damage induced by 1.8 GHz radiofrequency field for 2 h, which was mainly SSBs, may be associated with the increased ROS production. Electromagnetic noise could block RF-induced ROS formation and DNA damage. PMID:18509546

  19. Does Occupational Exposure of Shahid Dastghieb International Airport Workers to Radiofrequency Radiation Affect Their Short Term Memory and Reaction Time?

    PubMed Central

    Jarideh, S.; Taeb, S.; Pishva, S. M.; Haghani, M.; Sina, S.; Mortazavi, S. A. R.; Hosseini, M. A.; Nematollahi, S.; Shokrpour, N.; Hassan Shahi, M.; Mortazavi, S. M. J.

    2015-01-01

    Background Airport workers are continuously exposed to different levels of radiofrequency microwave (RF/MW) radiation emitted by radar equipments. Radars are extensively used in military and aviation industries. Over the past several years, our lab has focused on the health effects of exposure to different sources of electromagnetic fields such as cellular phones, mobile base stations, mobile phone jammers, laptop computers, radars, dentistry cavitrons and MRI. The main goal of this study was to investigate if occupational exposure of Shahid Dastghieb international airport workers to radiofrequency radiation affects their short term memory and reaction time. Methods Thirty two airport workers involved in duties at control and approach tower (21 males and 11 females), with the age range of 27-67 years old (mean age of 37.38), participated voluntary in this study. On the other hand, 29 workers (13 males, and 16 females) whose offices were in the city with no exposure history to radar systems were also participated in this study as the control group. The employees’ reaction time and short term memory were analyzed using a standard visual reaction time (VRT) test software and the modified Wechsler memory scale test, respectively. Results The mean± SD values for the reaction times of the airport employees (N=32) and the control group (N=29) were 0.45±0.12 sec and 0.46±0.17 sec, respectively.  Moreover, in the four subset tests; i.e. paired words, forward digit span, backward digit span and word recognition, the following points were obtained for the airport employees and the control group, respectively: (i) pair words test: 28.00±13.13 and 32.07±11.65, (ii) forward digit span: 8.38±1.40 and 9.03±1.32, (iii) backward digit span: 5.54±1.87 and 6.31±1.46, and (iv) word recognition: 5.73±2.36 and 6.50±1.93. These differences were not statistically significant. Conclusion The occupational exposure of the employees to the RF radiation in Shahid Dastghieb

  20. Measurement of DNA damage and apoptosis in Molt-4 cells after in vitro exposure to radiofrequency radiation.

    PubMed

    Hook, Graham J; Zhang, Peng; Lagroye, I; Li, Li; Higashikubo, Ryuji; Moros, Eduardo G; Straube, William L; Pickard, William F; Baty, Jack D; Roti Roti, Joseph L

    2004-02-01

    To determine whether exposure to radiofrequency (RF) radiation can induce DNA damage or apoptosis, Molt-4 T lymphoblastoid cells were exposed with RF fields at frequencies and modulations of the type used by wireless communication devices. Four types of frequency/modulation forms were studied: 847.74 MHz code-division multiple-access (CDMA), 835.62 MHz frequency-division multiple-access (FDMA), 813.56 MHz iDEN(R) (iDEN), and 836.55 MHz time-division multiple-access (TDMA). Exponentially growing cells were exposed to RF radiation for periods up to 24 h using a radial transmission line (RTL) exposure system. The specific absorption rates used were 3.2 W/kg for CDMA and FDMA, 2.4 or 24 mW/kg for iDEN, and 2.6 or 26 mW/kg for TDMA. The temperature in the RTLs was maintained at 37 degrees C +/- 0.3 degrees C. DNA damage was measured using the single-cell gel electrophoresis assay. The annexin V affinity assay was used to detect apoptosis. No statistically significant difference in the level of DNA damage or apoptosis was observed between sham-treated cells and cells exposed to RF radiation for any frequency, modulation or exposure time. Our results show that exposure of Molt-4 cells to CDMA, FDMA, iDEN or TDMA modulated RF radiation does not induce alterations in level of DNA damage or induce apoptosis. PMID:14731070

  1. Long-term bioeffects of 435-MHz radiofrequency radiation on selected blood-borne endpoints in cannulated rats. Volume 6. Cardiovascular studies. Final report, October 1982-June 1985

    SciTech Connect

    Popovic, V.P.; Toler, J.C.; Bonasera, S.J.; Popovic, P.P.; Honeycutt, C.B.

    1988-01-01

    Two hundred adult male white rats with chronically implanted aortic cannulas were randomly divided into 2 groups. Animals in the first group were exposed to low-level pulsed-wave 435-MHz radiofrequency radiation for approximately 22 hours daily, 7 days a week, for 6 months. Animals in the second group were maintained under identical conditions but were not radiated. The cannulas were used to record heart rate and arterial blood pressure in unrestrained, unanesthetized rats. Statistical analysis of the results did not indicate any increase in heart rate or arterial blood pressure of RFR-exposed animals when compared to sham-exposed animals. Thus, chronic exposure to the low-level radiofrequency environment did not induce stress that was manifested as increases in heart rate or mean arterial blood pressure. This result correlated with the conclusion of a previous report demonstrating no RFR effects on plasma norepinephrine and epinephrine concentrations in the group of rats.

  2. Long-term bioeffects of 435-MHz radiofrequency radiation on selected blood-borne endpoints in cannulated rats. Volume 4. Plasma catecholamines. Final report, October 1982-June 1985

    SciTech Connect

    Popovic, V.P.; Toler, J.C.; Bonasera, S.J.; Popovic, P.P.; Honeycutt, C.B.

    1987-08-01

    Two hundred adult male white rates (Sprague-Dawley) with chronically implanted aortic cannulas were randomly divided into two groups. Animals in the first group were exposed to low-level (1.0mW/sq cm) pulsed-wave 435-MHz radiofrequency radiation (RFR) for about 22 h daily, 7 days each week for 6 months. Animals in the second group were maintained under identical conditions but were not irradiated. The aortic cannulas were used to draw microsamples (0.6 mL) of aortic blood from the unrestrained, unanesthetized rats on a cyclic schedule. Plasma catecholamine (nonrepinephrine, epinephrine, and dopamine) concentrations were determined by radioimmunoassays. Statistical analysis of the results did not indicate increased plasma catecholamine concentrations on radiation-exposed animals when compared to sham-exposed animals. Exposure to this nonionizing radiofrequency (RF) environment did not induce stresses that were manifested as an alteration in plasma hormones.

  3. Interaction of ionizing radiation, genetically active chemicals, and radiofrequency radiation in human and rodent cells. Final report 1 Oct 87-30 Sep 89

    SciTech Connect

    Meltz, M.L.; Holahan, P.K.; Smith, S.T.; Kerbacher, J.J.; Ciaravino, V.

    1990-12-01

    The purpose of this project was to investigate the possible interaction between radiofrequency radiation (RFR) and agents which are known to damage DNA. Experiments were performed using exposures of CHO cells to 350, 850, 1200, and 2450 MHz RFR at up to 40 W/kg and temperatures ranging from 37 to 40 C. No genotoxic effect was observed by sister chromotid exchange induction, chromosome aberration induction, or gene mutation (at the thymidine kinase locus). At levels at or below 10 mW/cm2 and specific absorption rates (SARs) at or below 4 W/kg, there was no evidence that DNA repair was induced or repair of preexisting DNA damage was inhibited. Adriamycin but not mitomycin c caused a statistically significant increase in the frequency of aberrant cells at 40 C with or without RFR. These observations support thermal mechanisms of RFR interaction.

  4. Effects of radiofrequency radiation on human ferritin: an in vitro enzymun assay.

    PubMed

    Fattahi-Asl, Jafar; Baradaran-Ghahfarokhi, Molood; Karbalae, Mojtaba; Baradaran-Ghahfarokhi, Milad; Baradaran-Ghahfarokhi, Hamid Reza

    2012-10-01

    Ferritin is a macromolecule and is responsible for the long term iron storage function in human serum and plasma. Recent studies have highlighted the role of cell phone exposure on central nervous system, immune function and reproduction. The aim of this study was to investigate whether the human serum ferritin level could be interfered by the exposure to the 900 MHz GSM cell phones. Fifty human serum wells from 25 normal healthy donors were labeled with ruthenium to form a sandwich complex based on an immunoassay technique. All of them were placed into two batches, and the well heads in the first batch were exposed to 900 MHz exposure emitted from a speech mode cell phone (Nokia, Model 1202, India) for 30 min. Unexposed batch was served as the control sample under identical conditions and was compared with the exposed one in quantitative determination of ferritin using the Wilcoxon test with criterion level of P = 0.050. Human serum wells in the exposed batch showed a significant decrease in serum ferritin relative to the control batch (P = 0.029). The average ± SD ferritin level in the exposed batch was 84.94 ± 1.04 μg/L while it was 87.25 ± 0.83 μg/L for the unexposed batch. Radiofrequency electromagnetic waves emitted from cell phones may lead to oxidative stress and rapid diffusion of the human ferritin level in an in vitro enzymun assay. Also, the enzyme activity can be affected. Effects of exposure from mobile phones must be considered further. PMID:23724375

  5. Effects of combined radiofrequency radiation exposure on levels of reactive oxygen species in neuronal cells.

    PubMed

    Kang, Kyoung Ah; Lee, Hyung Chul; Lee, Je-Jung; Hong, Mi-Na; Park, Myung-Jin; Lee, Yun-Sil; Choi, Hyung-Do; Kim, Nam; Ko, Young-Gyu; Lee, Jae-Seon

    2014-03-01

    The objective of this study was to investigate the effects of the combined RF radiation (837 MHz CDMA plus 1950 MHz WCDMA) signal on levels of intracellular reactive oxygen species (ROS) in neuronal cells. Exposure of the combined RF signal was conducted at specific absorption rate values of 2 W/kg of CDMA plus 2 W/kg of WCDMA for 2 h. Co-exposure to combined RF radiation with either H2O2 or menadione was also performed. The experimental exposure groups were incubator control, sham-exposed, combined RF radiation-exposed with or without either H2O2 or menadione groups. The intracellular ROS level was measured by flow cytometry using the fluorescent probe dichlorofluorescein diacetate. Intracellular ROS levels were not consistently affected by combined RF radiation exposure alone in a time-dependent manner in U87, PC12 or SH-SY5Y cells. In neuronal cells exposed to combined RF radiation with either H2O2 or menadione, intracellular ROS levels showed no statically significant alteration compared with exposure to menadione or H2O2 alone. These findings indicate that neither combined RF radiation alone nor combined RF radiation with menadione or H2O2 influences the intracellular ROS level in neuronal cells such as U87, PC12 or SH-SY5Y. PMID:24105709

  6. The 2100MHz radiofrequency radiation of a 3G-mobile phone and the DNA oxidative damage in brain.

    PubMed

    Sahin, Duygu; Ozgur, Elcin; Guler, Goknur; Tomruk, Arın; Unlu, Ilhan; Sepici-Dinçel, Aylin; Seyhan, Nesrin

    2016-09-01

    We aimed to evaluate the effect of 2100MHz radiofrequency radiation emitted by a generator, simulating a 3G-mobile phone on the brain of rats during 10 and 40 days of exposure. The female rats were randomly divided into four groups. Group I; exposed to 3G modulated 2100MHz RFR signal for 6h/day, 5 consecutive days/wk for 2 weeks, group II; control 10 days, were kept in an inactive exposure set-up for 6h/day, 5 consecutive days/wk for 2 weeks, group III; exposed to 3G modulated 2100MHz RFR signal for 6h/day, 5 consecutive days/wk for 8 weeks and group IV; control 40 days, were kept in an inactive exposure set-up for 6h/day, 5 consecutive days/wk for 8 weeks. After the genomic DNA content of brain was extracted, oxidative DNA damage (8-hydroxy-2'deoxyguanosine, pg/mL) and malondialdehyde (MDA, nmoL/g tissue) levels were determined. Our main finding was the increased oxidative DNA damage to brain after 10 days of exposure with the decreased oxidative DNA damage following 40 days of exposure compared to their control groups. Besides decreased lipid peroxidation end product, MDA, was observed after 40 days of exposure. The measured decreased quantities of damage during the 40 days of exposure could be the means of adapted and increased DNA repair mechanisms. PMID:26775761

  7. Melatonin and a spin-trap compound block radiofrequency electromagnetic radiation-induced DNA strand breaks in rat brain cells.

    PubMed

    Lai, H; Singh, N P

    1997-01-01

    Effects of in vivo microwave exposure on DNA strand breaks, a form of DNA damage, were investigated in rat brain cells. In previous research, we have found that acute (2 hours) exposure to pulsed (2 microseconds pulses, 500 pps) 2450-MHz radiofrequency electromagnetic radiation (RFR) (power density 2 mW/cm2, average whole body specific absorption rate 1.2 W/kg) caused an increase in DNA single- and double-strand breaks in brain cells of the rat when assayed 4 hours post exposure using a microgel electrophoresis assay. In the present study, we found that treatment of rats immediately before and after RFR exposure with either melatonin (1 mg/kg/injection, SC) or the spin-trap compound N-tert-butyl-alpha-phenylnitrone (PBN) (100 mg/kg/injection, i.p.) blocks this effects of RFR. Since both melatonin and PBN are efficient free radical scavengers it is hypothesized that free radicals are involved in RFR-induced DNA damage in the brain cells of rats. Since cumulated DNA strand breaks in brain cells can lead to neurodegenerative diseases and cancer and an excess of free radicals in cells has been suggested to be the cause of various human diseases, data from this study could have important implications for the health effects of RFR exposure. PMID:9261542

  8. Thermal and physiologic responses to 1200-MHz radiofrequency radiation: Differences between exposure in E and H orientation

    SciTech Connect

    Jauchem, J.R.; Frei, M.R.; Padilla, J.M. )

    1990-09-01

    Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 1200-MHz continuous wave radiofrequency radiation in both E and H orientations (long axis of animal parallel to electric or magnetic field, respectively). Power densities were used that resulted in equivalent whole-body specific absorption rates of approximately 8 W/kg in both orientations (20 mW/cm{sup 2} for E and 45 mW/cm{sup 2} for H). Exposure was conducted to repeatedly increase colonic temperature from 38.5 to 39.5{degrees}C in both orientations in the same animal. Irradiation in E orientation resulted in greater colonic, tympanic, left subcutaneous (side toward antenna), and tail heating. The results indicated a more uniform distribution of heat than that which occurred in previous experiments of 2450-MHz irradiation in E and H orientation. A lack of significant differences in blood pressure and heart rate responses between exposures in the two orientations in this study suggest that greater peripheral heating, as was seen in the earlier study of 2450 MHz, is necessary for these differences to occur.

  9. In vitro fertilization of mouse ova by spermatozoa exposed isothermally to radio-frequency radiation

    SciTech Connect

    Cleary, S.F.; Liu, L.M.; Graham, R.; East, J. )

    1989-01-01

    Mouse spermatozoa were exposed in vitro for 1 h to 27- or 2,450-MHz CW RF radiation at SARs of 0 to 90 W/kg under isothermal (37 +/- 0.2 degrees C) conditions. Exposure at either frequency to RF radiation at SARs of 50 W/kg or greater resulted in a statistically significant reduction in the ability of irradiated sperm to fertilize mouse ova in vitro (P less than .05). Over the range of SARs there was no apparent difference in the effects of 27- vs. 2,450-MHz RF radiation. There were no readily detectable exposure effects on spermatozoan morphology, ultrastructure, or capacitation. The reduction of in vitro fertilization is attributed to a direct effect of RF radiation on spermatozoa rather than to heating.

  10. 47 CFR 2.1091 - Radiofrequency radiation exposure evaluation: mobile devices.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... between the transmitter's radiating structure(s) and the body of the user or nearby persons. In this... 22 of this chapter, parts 24, 25, 26 and 27 of this chapter, part 80 of this chapter (ship...

  11. 47 CFR 2.1093 - Radiofrequency radiation exposure evaluation: portable devices.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... device is defined as a transmitting device designed to be used so that the radiating structure(s) of the... 22 of this chapter, parts 24, 25, 26, 27, 80 (ship earth station devices only) and 90 of this...

  12. Does prolonged radiofrequency radiation emitted from Wi-Fi devices induce DNA damage in various tissues of rats?

    PubMed

    Akdag, Mehmet Zulkuf; Dasdag, Suleyman; Canturk, Fazile; Karabulut, Derya; Caner, Yusuf; Adalier, Nur

    2016-09-01

    Wireless internet (Wi-Fi) providers have become essential in our daily lives, as wireless technology is evolving at a dizzying pace. Although there are different frequency generators, one of the most commonly used Wi-Fi devices are 2.4GHz frequency generators. These devices are heavily used in all areas of life but the effect of radiofrequency (RF) radiation emission on users is generally ignored. Yet, an increasing share of the public expresses concern on this issue. Therefore, this study intends to respond to the growing public concern. The purpose of this study is to reveal whether long term exposure of 2.4GHz frequency RF radiation will cause DNA damage of different tissues such as brain, kidney, liver, and skin tissue and testicular tissues of rats. The study was conducted on 16 adult male Wistar-Albino rats. The rats in the experimental group (n=8) were exposed to 2.4GHz frequency radiation for over a year. The rats in the sham control group (n=8) were subjected to the same experimental conditions except the Wi-Fi generator was turned off. After the exposure period was complete the possible DNA damage on the rat's brain, liver, kidney, skin, and testicular tissues was detected through the single cell gel electrophoresis assay (comet) method. The amount of DNA damage was measured as percentage tail DNA value. Based on the DNA damage results determined by the single cell gel electrophoresis (Comet) method, it was found that the% tail DNA values of the brain, kidney, liver, and skin tissues of the rats in the experimental group increased more than those in the control group. The increase of the DNA damage in all tissues was not significant (p>0.05). However the increase of the DNA damage in rat testes tissue was significant (p<0.01). In conclusion, long-term exposure to 2.4GHz RF radiation (Wi-Fi) does not cause DNA damage of the organs investigated in this study except testes. The results of this study indicated that testes are more sensitive organ to RF

  13. ADVANCES IN EXPERIMENTAL EXPOSURE METHODS AND DOSIMETRIC TECHNIQUES USED IN RADIO-FREQUENCY RADIATION BIOLOGICAL EFFECTS STUDIES

    EPA Science Inventory

    The various techniques and methodologies used for exposure and dosimetric assessment in radio-frequency (RF) biological effects studies are reviewed. Techniques are compared and the advantages and disadvantages of each are discussed. Significant progress has been made during the ...

  14. EXPOSURE OF RATS TO 425-MHZ (CW) RADIOFREQUENCY RADIATION: EFFECTS ON LYMPHOCYTES

    EPA Science Inventory

    Four experiments were performed in which six pregnant rats were exposed from day 12 of pregnancy to parturition, for 4 hours a day in a temperature-controlled environment, to 425-MHz (CW) radiation, using a multimode rectangular strip transmission line. Four male pups born to eac...

  15. IMPROVED TECHNIQUE FOR MONITORING ELECTROCARDIOGRAMS DURING EXPOSURE TO RADIO-FREQUENCY RADIATION

    EPA Science Inventory

    Studies were conducted which examined the effects of radio frequency (RF) radiation on heart rate (HR), deep body temperature (TEMP), and electrocardiographic (ECG) waveform parameters in anesthetized rats. One group of animals was exposed to two power levels of continuous wave R...

  16. CALCIUM ION EFFLUX INDUCTION IN BRAIN TISSUE BY RADIO-FREQUENCY RADIATION

    EPA Science Inventory

    One of the most interesting and controversial papers on the biological effects of nonionizing radiation was published by Bawin, Kaczmarek and Adey in 1975. They found a 147 MHz carrier wave could elicit and enhance efflux of calcium ions from chick brain tissue only when amplitud...

  17. Improved technique for monitoring electrocardiograms during exposure to radio-frequency radiation

    SciTech Connect

    Watkinson, W.P.; Gordon, C.J.

    1986-01-01

    Studies were conducted which examined the effects of radio frequency (RF) radiation on heart rate (HR), deep body temperature (TEMP), and electrocardiographic (ECG) waveform parameters in anesthetized rats. One group of animals was exposed to two power levels of continuous wave RF radiation averaging 1.0 and 7.4 W/kg at a frequency of 600 MHz. A second group of animals, treated identically but not exposed to RF radiation, served as a control. The electrodes used to monitor the ECG during RF exposure were fabricated using carbon-loaded Teflon wire, a semiconductor material that does not perturb the RF field. Analyses of the ECG were conducted using a recently developed computer-assisted procedure which quantitates HR and waveform intervals over 25-40 individual ECG complexes. There were no artifacts or arrhythmias in the ECGs of the animals exposed to RF radiation. There was a significant linear correlation between HR and TEMP in the RF-exposed group which was not present in the control group.

  18. BIOLOGICAL EFFECTS OF LONG-TERM EXPOSURE OF RATS TO 970-MHZ RADIOFREQUENCY RADIATION

    EPA Science Inventory

    Rats (N=16) exposed individually in circularly polarized waveguides to 970-MHz electromagnetic radiation (SAR=2.5 mW/g, 22 h daily for 70 consecutive days) had significantly higher serum levels of triglycerides, albumin, and total protein compared with sham-irradiated controls. N...

  19. A survey of radiation dose to patients and operators during radiofrequency ablation using computed tomography

    PubMed Central

    Saidatul, A; Azlan, CA; Megat Amin, MSA; Abdullah, BJJ; Ng, KH

    2010-01-01

    Computed tomography (CT) fluoroscopy is able to give real time images to a physician undertaking minimally invasive procedures such as biopsies, percutaneous drainage, and radio frequency ablation (RFA). Both operators executing the procedure and patients too, are thus at risk of radiation exposure during a CT fluoroscopy. This study focuses on the radiation exposure present during a series of radio frequency ablation (RFA) procedures, and used Gafchromic film (Type XR-QA; International Specialty Products, USA) and thermoluminescent dosimeters (TLD-100H; Bicron, USA) to measure the radiation received by patients undergoing treatment, and also operators subject to scatter radiation. The voltage was held constant at 120 kVp and the current 70mA, with 5mm thickness. The duration of irradiation was between 150-638 seconds. Ultimately, from a sample of 30 liver that have undergone RFA, the study revealed that the operator received the highest dose at the hands, which was followed by the eyes and thyroid, while secondary staff dosage was moderately uniform across all parts of the body that were measured. PMID:21611060

  20. Estimation of Radiofrequency Power Leakage from Microwave Ovens for Dosimetric Assessment at Nonionizing Radiation Exposure Levels

    PubMed Central

    Lopez-Iturri, Peio; de Miguel-Bilbao, Silvia; Aguirre, Erik; Azpilicueta, Leire; Falcone, Francisco; Ramos, Victoria

    2015-01-01

    The electromagnetic field leakage levels of nonionizing radiation from a microwave oven have been estimated within a complex indoor scenario. By employing a hybrid simulation technique, based on coupling full wave simulation with an in-house developed deterministic 3D ray launching code, estimations of the observed electric field values can be obtained for the complete indoor scenario. The microwave oven can be modeled as a time- and frequency-dependent radiating source, in which leakage, basically from the microwave oven door, is propagated along the complete indoor scenario interacting with all of the elements present in it. This method can be of aid in order to assess the impact of such devices on expected exposure levels, allowing adequate minimization strategies such as optimal location to be applied. PMID:25705676

  1. Estimation of radiofrequency power leakage from microwave ovens for dosimetric assessment at nonionizing radiation exposure levels.

    PubMed

    Lopez-Iturri, Peio; de Miguel-Bilbao, Silvia; Aguirre, Erik; Azpilicueta, Leire; Falcone, Francisco; Ramos, Victoria

    2015-01-01

    The electromagnetic field leakage levels of nonionizing radiation from a microwave oven have been estimated within a complex indoor scenario. By employing a hybrid simulation technique, based on coupling full wave simulation with an in-house developed deterministic 3D ray launching code, estimations of the observed electric field values can be obtained for the complete indoor scenario. The microwave oven can be modeled as a time- and frequency-dependent radiating source, in which leakage, basically from the microwave oven door, is propagated along the complete indoor scenario interacting with all of the elements present in it. This method can be of aid in order to assess the impact of such devices on expected exposure levels, allowing adequate minimization strategies such as optimal location to be applied. PMID:25705676

  2. Critique of the literature on bioeffects of radio-frequency radiation. A comprehensive review pertinent to Air Force operations. Final report, June 1982-October 1986

    SciTech Connect

    Heynick, L.N.

    1987-06-01

    This report analyzes research results and other pertinent information on the biological effects of radiofrequency radiation (RFR). The frequency range of primary interest is 10 kHz to 300 GHz. The main purpose of this report is to serve as a basic reference for other documents dealing with the environmental impact of proposed or currently operating USAF emitter systems with regards to health and safety aspects of exposure to RFR. The report is divided into 7 sections with various aspects of the present knowledge regarding biological effects of RFR. More than 600 references from the world's literature are cited.

  3. Measurement of radiofrequency fields

    NASA Astrophysics Data System (ADS)

    Leonowich, J. A.

    1992-05-01

    We are literally surrounded by radiofrequency (RFR) and microwave radiation, from both natural and man-made sources. The identification and control of man-made sources of RFR has become a high priority of radiation safety professionals in recent years. For the purposes of this paper, we will consider RFR to cover the frequencies from 3 kHz to 300 MHz, and microwaves from 300 MHz to 300 GHz, and will use the term RFR interchangeably to describe both. Electromagnetic radiation below 3 kHz is considered Extremely Low Frequency (ELF) and will not be discussed in this paper. Unlike x- and gamma radiation, RFR is non-ionizing. The energy of any RFR photon is insufficient to produce ionizations in matter. The measurement and control of RFR hazards is therefore fundamentally different from ionizing radiation. The purpose of this paper is to acquaint the reader with the fundamental issues involved in measuring and safely using RFR fields.

  4. Definition of procedure to study bioeffects of radiofrequency radiation on cell growth and differentiation. Final report, 1 March-30 October 1986

    SciTech Connect

    Toler, J.C.; Bonasera, S.J.

    1987-05-01

    This research program was conducted for the purpose of evaluating the feasibility of using an existing multi-animal radiation facility to expose a large population of experimental animals to electromagnetic radiation in the radiofrequency portion of the spectrum. The major conclusion of this program was that the multi-animal facility at the Georgia Tech Research Institute would provide a suitable exposure environment for investigating chronic RFR effects on the growth and differentiation of rapidly growing mammalian cells in vivo. This conclusion was reached in collaboration with experts in experimental and diagnostic pathology from Pathology Associates, Inc., Ijamsville, Maryland. The Appendix to this report presents a proposed protocol for a follow-on research program to investigate RFR bioeffects on cell growth and differentiation. This protocol identifies an animal model, animal population, exposure environment, exposure duration, and tissue assessment scheme appropriate for the proposed follow-on investigation.

  5. Genetic damage in mammalian somatic cells exposed to radiofrequency radiation: a meta-analysis of data from 63 publications (1990-2005).

    PubMed

    VIjayalaxmi; Prihoda, Thomas J

    2008-05-01

    During the last several decades, numerous researchers have examined the potential of in vitro and /or in vivo exposure of radiofrequency( RF) radiation to damage the genetic material in mammalian somatic cells. A meta-analysis of reported data was conducted to obtain a quantitative estimate ( with 95% confidence intervals) of genotoxicity in RF-radiation-exposed cells compared with sham-exposed/unexposed control cells. The extent of genotoxicity was assessed for various end points, including single- and double-strand breaks in the DNA, incidence of chromosomal aberrations, micronuclei and sister chromatid exchanges. Among the several variables in the experimental protocols used in individual investigations, the influence of three specific variables related to RF-radiation exposure characteristics was examined in the meta-analysis: frequency, specific absorption rate, and exposure as continuous-wave, pulsed-wave and occupationally exposed/cell phone users. The overall data indicated that (1) the difference between RF-radiation exposure was small with few exceptions; (2) at certain RF radiation exposure conditions, there were statistically significant increases in genotoxicity for some end points; and (3) the mean indices for chromosomal aberrations and micronuclei in RF-radiation -exposed and sham-/unexposed controls were within the spontaneous levels reported in the historical database. Considerable evidence for publication bias was found in the meta-analysis. PMID:18494173

  6. Adaptive response in mouse bone-marrow stromal cells exposed to 900-MHz radiofrequency fields: Gamma-radiation-induced DNA strand breaks and repair.

    PubMed

    Ji, Yongxin; He, Qina; Sun, Yulong; Tong, Jian; Cao, Yi

    2016-01-01

    The aim of this study was to examine whether radiofrequency field (RF) preexposure induced adaptive responses (AR) in mouse bone-marrow stromal cells (BMSC) and the mechanisms underlying the observed findings. Cells were preexposed to 900-MHz radiofrequency fields (RF) at 120 μW/cm(2) power intensity for 4 h/d for 5 d. Some cells were subjected to 1.5 Gy γ-radiation (GR) 4 h following the last RF exposure. The intensity of strand breaks in the DNA was assessed immediately at 4 h. Subsequently, some BMSC were examined at 30, 60, 90, or 120 min utilizing the alkaline comet assay and γ-H2AX foci technique. Data showed no significant differences in number and intensity of strand breaks in DNA between RF-exposed and control cells. A significant increase in number and intensity of DNA strand breaks was noted in cells exposed to GR exposure alone. RF followed by GR exposure significantly decreased number of strand breaks and resulted in faster kinetics of repair of DNA strand breaks compared to GR alone. Thus, data suggest that RF preexposure protected cells from damage induced by GR. Evidence indicates that in RF-mediated AR more rapid repair kinetics occurs under conditions of GR-induced damage, which may be attributed to diminished DNA strand breakage. PMID:27267824

  7. Studying the protein expression in human B lymphoblastoid cells exposed to 1.8-GHz (GSM) radiofrequency radiation (RFR) with protein microarray.

    PubMed

    Zhijian, Chen; Xiaoxue, Li; Wei, Zheng; Yezhen, Lu; Jianlin, Lou; Deqiang, Lu; Shijie, Chen; Lifen, Jin; Jiliang, He

    2013-03-29

    In the present study, the protein microarray was used to investigate the protein expression in human B-cell lymphoblastoid cells intermittently exposed to 1.8-GHz GSM radiofrequency radiation (RFR) at the specific absorption rate (SAR) of 2.0 W/kg for 24 h. The differential expression of 27 proteins was found, which were related to DNA damage repair, apoptosis, oncogenesis, cell cycle and proliferation (ratio >1.5-fold, P<0.05). The results validated with Western blot assay indicated that the expression of RPA32 was significantly down-regulated (P<0.05) while the expression of p73 was significantly up-regulated in RFR exposure group (P<0.05). Because of the crucial roles of those proteins in DNA repair and cell apoptosis, the results of present investigation may explain the biological effects of RFR on DNA damage/repair and cell apoptosis. PMID:23454122

  8. Cytogenetic studies in human blood lymphocytes exposed in vitro to radiofrequency radiation at a cellular telephone frequency (835.62 MHz, FDMA).

    PubMed

    Vijayalaxmi; Leal, B Z; Meltz, M L; Pickard, W F; Bisht, K S; Roti Roti JL; Straube, W L; Moros, E G

    2001-01-01

    Freshly collected peripheral blood samples from four healthy human volunteers were diluted with RPMI 1640 tissue culture medium and exposed in sterile T-75 tissue culture flasks in vitro for 24 h to 835.62 MHz radiofrequency (RF) radiation, a frequency employed for customer-to-base station transmission of cellular telephone communications. An analog signal was used, and the access technology was frequency division multiple access (FDMA, continuous wave). A nominal net forward power of 68 W was used, and the nominal power density at the center of the exposure flask was 860 W/m(2). The mean specific absorption rate in the exposure flask was 4.4 or 5.0 W/kg. Aliquots of diluted blood that were sham-exposed or exposed in vitro to an acute dose of 1.50 Gy of gamma radiation were used as negative or positive controls. Immediately after the exposures, the lymphocytes were stimulated with a mitogen, phytohemagglutinin, and cultured for 48 or 72 h to determine the extent of genetic damage, as assessed from the frequencies of chromosomal aberrations and micronuclei. The extent of alteration in the kinetics of cell proliferation was determined from the mitotic indices in 48-h cultures and from the incidence of binucleate cells in 72-h cultures. The data indicated no significant differences between RF-radiation- and sham-exposed lymphocytes with respect to mitotic indices, incidence of exchange aberrations, excess fragments, binucleate cells, and micronuclei. In contrast, the response of the lymphocytes exposed to gamma radiation was significantly different from both RF-radiation- and sham-exposed cells for all of these indices. Thus, under the experimental conditions tested, there is no evidence for the induction of chromosomal aberrations and micronuclei in human blood lymphocytes exposed in vitro for 24 h to 835.62 MHz RF radiation at SARs of 4.4 or 5.0 W/kg. PMID:11121222

  9. New Horizons in Enhancing the Proliferation and Differentiation of Neural Stem Cells Using Stimulatory Effects of the Short Time Exposure to Radiofrequency Radiation.

    PubMed

    Eghlidospour, M; Mortazavi, S M J; Yousefi, F; Mortazavi, S A R

    2015-09-01

    Mobile phone use and wireless communication technology have grown explosively over the past decades. This rapid growth has caused widespread global concern about the potential detrimental effects of this technology on human health. Stem cells generate specialized cell types of the tissue in which they reside through normal differentiation pathways. Considering the undeniable importance of stem cells in modern medicine, numerous studies have been performed on the effects of ionizing and non-ionizing radiation on cellular processes such as: proliferation, differentiation, cell cycle and DNA repair processes. We have conducted extensive studies on beneficial (stimulatory) or detrimental biological effects of exposure to different sources of electromagnetic fields such as mobile phones, mobile phone base stations, mobile phone jammers, radar systems, magnetic resonance imaging (MRI) systems and dentistry cavitrons over the past years. In this article, recent studies on the biological effects of non-ionizing electromagnetic radiation in the range of radiofrequency (RF) on some important features of stem cells such as their proliferation and differentiation are reviewed. Studies reviewed in this paper indicate that the stimulatory or inhibitory effects of RF radiation on the proliferation and differentiation of stem cells depend on various factors such as the biological systems, experiment conditions, the frequency and intensity of RF and the duration of exposure. PMID:26396965

  10. New Horizons in Enhancing the Proliferation and Differentiation of Neural Stem Cells Using Stimulatory Effects of the Short Time Exposure to Radiofrequency Radiation

    PubMed Central

    Eghlidospour, M.; Mortazavi, S. M. J.; Yousefi, F.; Mortazavi, S. A. R.

    2015-01-01

    Mobile phone use and wireless communication technology have grown explosively over the past decades. This rapid growth has caused widespread global concern about the potential detrimental effects of this technology on human health. Stem cells generate specialized cell types of the tissue in which they reside through normal differentiation pathways. Considering the undeniable importance of stem cells in modern medicine, numerous studies have been performed on the effects of ionizing and non-ionizing radiation on cellular processes such as: proliferation, differentiation, cell cycle and DNA repair processes. We have conducted extensive studies on beneficial (stimulatory) or detrimental biological effects of exposure to different sources of electromagnetic fields such as mobile phones, mobile phone base stations, mobile phone jammers, radar systems, magnetic resonance imaging (MRI) systems and dentistry cavitrons over the past years. In this article, recent studies on the biological effects of non-ionizing electromagnetic radiation in the range of radiofrequency (RF) on some important features of stem cells such as their proliferation and differentiation are reviewed. Studies reviewed in this paper indicate that the stimulatory or inhibitory effects of RF radiation on the proliferation and differentiation of stem cells depend on various factors such as the biological systems, experiment conditions, the frequency and intensity of RF and the duration of exposure. PMID:26396965

  11. Cellular- and molecular- level responses after radiofrequency radiation exposure, alone or in combination with x rays or chemicals. Annual technical report, 1 Apr 91-31 Mar 92

    SciTech Connect

    Meltz, M.L.

    1992-07-30

    The focus of the first year's activities, at a time when a major recruitment of personnel was underway, revolved around: selection of the appropriate cell line for performing the mammalian cell mutagenicity studies; preliminary studies with the Balb/c 3T3 cell transformation assay; mutation spectrum analysis of the spontaneous mutants arising in AS52 and BH4 chinese hamster ovary (CHO) cell lines; liposome encapsulation studies of the polymer diazoluminomelanin (DALM); and redesign of the thermal control system originally constructed as a prototype for the Radiofrequency Radiation Division at USAF Armstrong Laboratory. Most importantly, although the original proposal called for the study of the possible mutagenic interaction of microwaves and ionizing radiation using the AS52 line of CHO cells, the results of the mutation spectrum analysis study led to the decision to alter future protocols to perform these studies with the BH4 cells; otherwise, the experiments would predominantly be measuring small deletion type mutations, and would not have enough sensitivity to pick up alterations of other types of mutation which might occur due to the microwave exposures. In addition, the liposome studies revealed the difficulty of encapsulating chemically synthesized DALM in this biological system; these studies will need to be furthered using other resources. The redesign and construction of a modified thermal control system was begun, allowing for one control unit to perform the temperature measurement and temperature control functions in two separate incubator systems.

  12. The effect of low level radiofrequency electromagnetic radiation on the excretion rates of stress hormones in operators during 24-hour shifts.

    PubMed

    Vangelova, K; Israel, M; Mihaylov, S

    2002-06-01

    The aim of the study was to investigate the effect of long term exposure to low level radiofrequency (RF) electromagnetic (EM) radiation on the excretion rates of stress hormones in satellite station operators during 24-hour shifts. Twelve male operators at a satellite station for TV communications and space research were studied during 24-hour shifts. Dosimetric evaluation of the exposure was carried out and showed low level exposure with specific absorption of 0.1127 J.kg-1. A control group of 12 unexposed male operators with similar job task and the same shift system were studied, too. The 11-oxycorticosteroids (11-OCS), adrenaline and noradrenaline were followed by spectrofluorimetric methods on 3-hour intervals during the 24-hour shifts. The data were analyzed by tests for interindividual analysis, Cosinor analysis and analysis of variance (ANOVA). Significant increase in the 24-hour excretion of 11-OCS and disorders in its circadian rhythm, manifested by increase in the mesor, decrease in the amplitude and shift in the acrophase were found in the exposed operators. The changes in the excretion rates of the catecholamines were significant and showed greater variability of both variables. The long term effect of the exposure to low-level RF EM radiation evoked pronounced stress reaction with changes in the circadian rhythm of 11-OCS and increased variability of catecholamines secretion. The possible health hazards associated with observed alteration in the stress system need to be clarified by identification of their significance and prognostic relevance. PMID:12096679

  13. Survey of the Effects of Exposure to 900 MHz Radiofrequency Radiation Emitted by a GSM Mobile Phone on the Pattern of Muscle Contractions in an Animal Model

    PubMed Central

    Mortazavi, S. M. J.; Rahimi, S.; Talebi, A.; Soleimani, A.; Rafati, A.

    2015-01-01

    Background: The rapid development of wireless telecommunication technologies over the past decades, has led to significant changes in the exposure of the general public to electromagnetic fields. Nowadays, people are continuously exposed to different sources of electromagnetic fields such as mobile phones, mobile base stations, cordless phones, Wi-Fi routers, and power lines. Therefore, the last decade witnessed a rapidly growing concern about the possible health effects of exposure to electromagnetic fields emitted by these sources. Materials and Methods: In this study that was aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted by a GSM mobile phone on the pattern of contraction in frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz), pulse height of contractions, the time interval between two subsequent contractions and the latency period were measured. Results: Our findings showed that the pulse height of contractions muscle could be affected by the exposure to electromagnetic fields. Especially, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion: These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions. PMID:26396968

  14. Long-term bioeffects of 435-MHz radiofrequency radiation on selected blood-borne endpoints in cannulated rats. Volume 2. Plasma ACTH (adrenocorticotropic hormone) and plasma corticosterone. Final report, 20 August 1984-16 February 1986

    SciTech Connect

    Popovic, V.P.; Toler, J.C.; Bonasera, S.J.; Popovic, P.P.; Honeycutt, C.B.

    1987-08-01

    Two hundred adult male white rats with chronically implanted aortic cannulas were randomly divided into two groups. Animals in the first group were exposed to low-level (1.0 mW/cm2) pulsed-wave 435-MHz radiofrequency radiation (RFR) for approximately 22 h daily, 7 days each week, for 6 months. Animals in the second group were maintained under identical conditions, but were not radiated. The cannulas were used to draw microsamples (0.3 mL) of aortic blood from the unrestrained, unanesthetized rats on a cyclic schedule. Plasma adrenocorticotropic hormone (ACTH) and plasma corticosterone concentrations were determined by radioimmunoassays hormone (ACTH) and plasma corticosterone concentrations were determined by radioimmunoassays. Statistical analysis of the results did not indicate increased plasma ACTH and plasma corticosterone concentrations in exposed animals when compared to sham-exposed animals. Exposure to this low-level radiofrequency environment did not induce stresses that were manifested as an alteration in plasma hormones.

  15. Measurement of radiofrequency fields

    SciTech Connect

    Leonowich, J.A.

    1992-05-01

    We are literally surrounded by radiofrequency (RFR) and microwave radiation, from both natural and man-made sources. The identification and control of man-made sources of RFR has become a high priority of radiation safety professionals in recent years. For the purposes of this paper, we will consider RFR to cover the frequencies from 3 kHz to 300 MHz, and microwaves from 300 MHz to 300 GHz, and will use the term RFR interchangeably to describe both. Electromagnetic radiation and field below 3 kHz is considered Extremely Low Frequency (ELF) and will not be discussed in this paper. Unlike x- and gamma radiation, RFR is non-ionizing. The energy of any RFR photon is insufficient to produce ionizations in matter. The measurement and control of RFR hazards is therefore fundamentally different from ionizing radiation. The purpose of this paper is to acquaint the reader with the fundamental issues involved in measuring and safely using RFR fields. 23 refs.

  16. Medicina array demonstrator: calibration and radiation pattern characterization using a UAV-mounted radio-frequency source

    NASA Astrophysics Data System (ADS)

    Pupillo, G.; Naldi, G.; Bianchi, G.; Mattana, A.; Monari, J.; Perini, F.; Poloni, M.; Schiaffino, M.; Bolli, P.; Lingua, A.; Aicardi, I.; Bendea, H.; Maschio, P.; Piras, M.; Virone, G.; Paonessa, F.; Farooqui, Z.; Tibaldi, A.; Addamo, G.; Peverini, O. A.; Tascone, R.; Wijnholds, S. J.

    2015-06-01

    One of the most challenging aspects of the new-generation Low-Frequency Aperture Array (LFAA) radio telescopes is instrument calibration. The operational LOw-Frequency ARray (LOFAR) instrument and the future LFAA element of the Square Kilometre Array (SKA) require advanced calibration techniques to reach the expected outstanding performance. In this framework, a small array, called Medicina Array Demonstrator (MAD), has been designed and installed in Italy to provide a test bench for antenna characterization and calibration techniques based on a flying artificial test source. A radio-frequency tone is transmitted through a dipole antenna mounted on a micro Unmanned Aerial Vehicle (UAV) (hexacopter) and received by each element of the array. A modern digital FPGA-based back-end is responsible for both data-acquisition and data-reduction. A simple amplitude and phase equalization algorithm is exploited for array calibration owing to the high stability and accuracy of the developed artificial test source. Both the measured embedded element patterns and calibrated array patterns are found to be in good agreement with the simulated data. The successful measurement campaign has demonstrated that a UAV-mounted test source provides a means to accurately validate and calibrate the full-polarized response of an antenna/array in operating conditions, including consequently effects like mutual coupling between the array elements and contribution of the environment to the antenna patterns. A similar system can therefore find a future application in the SKA-LFAA context.

  17. Effects of simultaneous radiofrequency radiation and chemical exposure of mammalian cells. Volume 2. Final report, 2 January 1984-31 December 1986

    SciTech Connect

    Meltz, M.L.; Ciaravino, V.; Kerbacher, J.J.; Eagan, P.

    1988-07-01

    A circulating water-bath exposure system was designed for in vitro radio-frequency radiation (RFR) exposure studies in the 915- to 2450-MHz range. A continuously rotating styrofoam float, holding ten T-25 tissue-culture flasks, averages out field heterogeneity and allows mixing in the medium in the flasks. The presence of cells in the exposure flask (as attached monolayer or cell suspension) did not result in an SAR different from that measured in the medium without cells present. Two hypotheses are posed relative to the mutagenic activity of RFR: (a) that RFR by itself is genotoxic to mammalian cells in vitro; and (b) that a simultaneous exposure of mammalian cells to RFR during treatment with a genotoxic chemical will result in an alteration of the genotoxic activity of the chemical alone. RFR exposure alone (at moderate power levels which resulted in a temperature increase in the cell-culture medium of no more than 3 C) is not mutagenic. During simultaneous treatment, the RFR does not affect either the inhibition of cell growth or the extent of mutagenesis resulting from the chemical treatment alone. The same two hypotheses were explored for induction of sister chromatid exchanges (SCEs) and chromosome aberrations in Chinese hamster ovary cells which were similarly exposed to RFR and chemicals. The chemicals studied for SCE induction were mitomycin C (MMC) and Adriamycin.

  18. Nanometer-scale elongation rate fluctuations in the Myriophyllum aquaticum (Parrot feather) stem were altered by radio-frequency electromagnetic radiation

    PubMed Central

    Senavirathna, Mudalige Don Hiranya Jayasanka; Asaeda, Takashi; Thilakarathne, Bodhipaksha Lalith Sanjaya; Kadono, Hirofumi

    2014-01-01

    The emission of radio-frequency electromagnetic radiation (EMR) by various wireless communication base stations has increased in recent years. While there is wide concern about the effects of EMR on humans and animals, the influence of EMR on plants is not well understood. In this study, we investigated the effect of EMR on the growth dynamics of Myriophyllum aquaticum (Parrot feather) by measuring the nanometric elongation rate fluctuation (NERF) using a statistical interferometry technique. Plants were exposed to 2 GHz EMR at a maximum of 1.42 Wm−2 for 1 h. After continuous exposure to EMR, M. aquaticum plants exhibited a statistically significant 51 ± 16% reduction in NERF standard deviation. Temperature observations revealed that EMR exposure did not cause dielectric heating of the plants. Therefore, the reduced NERF was due to a non-thermal effect caused by EMR exposure. The alteration in NERF continued for at least 2.5 h after EMR exposure and no significant recovery was found in post-EMR NERF during the experimental period. PMID:24670369

  19. Application of a temperature-dependent fluorescent dye (Rhodamine B) to the measurement of radiofrequency radiation-induced temperature changes in biological samples.

    PubMed

    Chen, Yuen Y; Wood, Andrew W

    2009-10-01

    We have applied a non-contact method for studying the temperature changes produced by radiofrequency (RF) radiation specifically to small biological samples. A temperature-dependent fluorescent dye, Rhodamine B, as imaged by laser scanning confocal microscopy (LSCM) was used to do this. The results were calibrated against real-time temperature measurements from fiber optic probes, with a calibration factor of 3.4% intensity change degrees C(-1) and a reproducibility of +/-6%. This non-contact method provided two-dimensional and three-dimensional images of temperature change and distributions in biological samples, at a spatial resolution of a few micrometers and with an estimated absolute precision of around 1.5 degrees C, with a differential precision of 0.4 degree C. Temperature rise within tissue was found to be non-uniform. Estimates of specific absorption rate (SAR) from absorbed power measurements were greater than those estimated from rate of temperature rise, measured at 1 min intervals, probably because this interval is too long to permit accurate estimation of initial temperature rise following start of RF exposure. Future experiments will aim to explore this. PMID:19507188

  20. Studying the protein expression in human B lymphoblastoid cells exposed to 1.8-GHz (GSM) radiofrequency radiation (RFR) with protein microarray

    SciTech Connect

    Zhijian, Chen; Institute of Environmental Health, Medical College, Zhejiang University, Hangzhou 310058, Zhejiang ; Xiaoxue, Li; Wei, Zheng; Yezhen, Lu; Jianlin, Lou; Deqiang, Lu; Shijie, Chen; Lifen, Jin; Jiliang, He

    2013-03-29

    Highlights: ► Protein microarray shows the differential expression of 27 proteins induced by RFR. ► RPA32 related to DNA repair is down-regulated in Western blot. ► p73 related to cell genome stability and apoptosis is up-regulated in Western blot. -- Abstract: In the present study, the protein microarray was used to investigate the protein expression in human B-cell lymphoblastoid cells intermittently exposed to 1.8-GHz GSM radiofrequency radiation (RFR) at the specific absorption rate (SAR) of 2.0 W/kg for 24 h. The differential expression of 27 proteins was found, which were related to DNA damage repair, apoptosis, oncogenesis, cell cycle and proliferation (ratio >1.5-fold, P < 0.05). The results validated with Western blot assay indicated that the expression of RPA32 was significantly down-regulated (P < 0.05) while the expression of p73 was significantly up-regulated in RFR exposure group (P < 0.05). Because of the crucial roles of those proteins in DNA repair and cell apoptosis, the results of present investigation may explain the biological effects of RFR on DNA damage/repair and cell apoptosis.

  1. Frequency-dependent energy absorption in the body and tail of the rodent carcass exposed to radiofrequency radiation. Final report, 31 June-31 December 1985

    SciTech Connect

    Bixby, R.R.; Padilla, J.M.

    1987-04-01

    The proportion of energy absorbed by the tail of a rat carcass was determined. Male (288 g - 457 g) and female (195 g - 249 g) Sprague-Dawley rat carcasses were exposed to far-field, continuous-wave radiofrequency radiation (RFR). The carcasses were split into two mixed groups: one group was exposed to 700-MHz RFR; and the other, to 350-MHz RFR. Immediately after each exposure, the tail was severed, and the specific absorption rates (SAR) of the tail and body were determined by Dewar flask calorimetry. For example, a 195 g female exposed to 700 MHz yielded SARs of 1.26 and 3.64 mW/g (normalized to 1 nW/cm2 incident power density) for its body and tail, respectively; the tail contributed 6.7% to the total energy absorption. For a 205 g female exposed to 350 MHz, however, the tail contributed 19.0% to the whole-body absorption. Normalized SARs of 0.40 and 4.03 nW/g per mW/cm2 were obtained for the body and tail, respectively.

  2. Effects of radiofrequency radiation and simultaneous exposure with mitomycin C on the frequency of sister chromatid exchanges in Chinese hamster ovary cells

    SciTech Connect

    Ciaravino, V.; Meltz, M.L.; Erwin, D.N.

    1987-01-01

    Chinese hamster ovary (CHO) cells were exposed for 2 hr with and without mitomycin C (MMC) (1 X 10(-8)M) to pulsed wave radiofrequency radiation (RFR) at 2450 MHz. The repetition rate of 25,000 pulses per sec (pps), pulse width of 10 microseconds, and exposure geometry used, resulted in a specific absorption rate (SAR) of 33.8 W/kg. The following exposure regimens were used: a 37 degrees C water bath control; a water bath temperature control (TC) in which the continuously monitored medium temperature closely followed the temperature rise in the RFR-exposed flasks; and the RFR-exposed cells in a water bath set at 37 degrees C prior to exposure. RFR exposure resulted in a maximum cell culture medium temperature of 39.2 degrees C. In the absence of MMC, there was no significant increase in sister chromatid exchange (SCE) in the RFR-exposed or TC groups over that of the 37 degrees C control. When a simultaneous treatment of RFR and MMC occurred there was no statistical difference in SCE frequency from that caused by chemical treatment alone.

  3. Effects of radiofrequency radiation and simultaneous exposure with mitomycin C on the frequency of sister chromatid exchanges in Chinese hamster ovary cells

    SciTech Connect

    Ciaravino, V.; Meltz, M.L.; Erwin, D.N.

    1987-01-01

    Chinese hamster ovary (CHO) cells were exposed for 2 hr with and without mitomycin C (MMC) to pulsed wave radiofrequency radiation (RFR) at 2450 MHz. The repetition rate of 25,000 pulses per sec (pps), and exposure geometry used, resulted in a specific absorption rate (SAR) of 33.8 W/kg. The following exposure regimens were used: 1) a 37 C water bath control; 2) a water bath temperature control (TC) in which the continuously monitored medium temperature closely followed teh temperature rise in the RFR-exposed flasks; and 3) the RFR-exposed cells in a water bath set at 37 C prior to exposure. RFR exposure resulted in a maximum cell culture medium temperature of 39.2 C. In the absence of MMC, there was no significant increase in sister chromatid exchange (SCE) in the RFR-exposed or TC groups over that of teh 37 C control. When a simultaneous treatment of RFR and MMC occurred there was no statistical difference in SCE frequency from that caused by chemical treatment alone.

  4. Definition of procedures for chronic exposure of cancer-prone mice to low-level 2,450-MHz radiofrequency radiation. Final report, Jan-Apr 91

    SciTech Connect

    Frei, M.R.; Merritt, J.H.

    1991-09-01

    Several published reports have implied that long-term, low-level exposure to radio-frequency radiation (RFR) may influence the growth and/or differentiation of mammalian cells in vivo. Specifically, the issue involves whether or not such RFR exposure can cause cells to differentiate into an invasive form (tumor induction) or can act as a promoter of tumor expression. To address this issue, the United States Air Force sponsors a project involving long-term exposure of tumor-prone mice to low-level 435-MHz RFR. An earlier onset, greater incidence, or faster growth rate of tumors in the irradiated group, as compared to sham irradiated controls, would suggest an enhanced tumor promotion potential. This investigation is essentially a parallel study to that being conducted at 435 MHz. The critical difference is the exposure frequency; this study will be conducted at 2,450 MHz, which is near the resonant frequency for mice. Knowledge gained from this study will contribute to the ongoing evaluation of safety standards for human exposure to RFR which is essential to the protection of military operational personnel and the general public.

  5. Absence of a synergistic effect between moderate-power radio-frequency electromagnetic radiation and adriamycin on cell-cycle progression and sister-chromatid exchange.

    PubMed

    Ciaravino, V; Meltz, M L; Erwin, D N

    1991-01-01

    In our laboratories we are conducting investigations of potential interactions between radio-frequency electromagnetic radiation (RFR) and chemicals that are toxic by different mechanisms to mammalian cells. The RFR is being tested at frequencies in the microwave range and at different power levels. We report here on the 1) ability of simultaneous RFR exposures to alter the distribution of cells in first and second mitoses from that after treatment by adriamycin alone, and 2) on the ability of simultaneous RFR exposure to alter the extent of sister chromatid exchanges (SCEs) induced by adriamycin alone. This chemical was selected because of its reported mechanism of action and because it is of interest in the treatment of cancer. In our studies, Chinese hamster ovary (CHO) cells were exposed for 2 h simultaneously to adriamycin and pulsed RFR at a frequency of 2,450 MHz and a specific absorption rate of 33.8 W/Kg. The maximal temperature (in the tissue-culture medium) was 39.7 +/- 0.2 degrees C. The experiments were controlled for chemical and RFR exposures, as well as for temperature. Verified statistically, the data indicate that the RFR did not affect changes in cell progression caused by adriamycin, and the RFR did not change the number of SCEs that were induced by the adriamycin, which adriamycin is known to affect cells by damaging their membranes and DNA. PMID:1759979

  6. Comparative study of cell cycle kinetics and induction of apoptosis or necrosis after exposure of human Mono Mac 6 cells to radiofrequency radiation.

    PubMed

    Lantow, M; Viergutz, T; Weiss, D G; Simkó, M

    2006-09-01

    The possible harmful effects of radiofrequency electromagnetic fields (RF EMFs) are controversial. We have used human Mono Mac 6 cells to investigate the influence of RF EMFs in vitro on cell cycle alterations and BrdU uptake, as well as the induction of apoptosis and necrosis in human Mono Mac 6 cells, using flow cytometry after exposure to a 1,800 MHz, 2 W/kg specific absorption rate (SAR), GSM-DTX signal for 12 h. No statistically significant differences in the induction of apoptosis or necrosis, cell cycle kinetics, or BrdU uptake were detected after RF EMF exposure compared to sham or incubator controls. However, in the positive control cells treated with gliotoxin and PMA (phorbol 12 myristate-13 acetate), a significant increase in apoptotic and necrotic cells was seen. Cell cycle analysis or BrdU incorporation for 72 h showed no differences between RF EMF- or sham-exposed cells, whereas PMA treatment induced a significant accumulation of cells in G(0)/G(1)-phase and a reduction in S-phase cells. RF EMF radiation did not induce cell cycle alterations or changes in BrdU incorporation or induce apoptosis and necrosis in Mono Mac 6 cells under the exposure conditions used. PMID:16953672

  7. Alteration of glycine receptor immunoreactivity in the auditory brainstem of mice following three months of exposure to radiofrequency radiation at SAR 4.0 W/kg

    PubMed Central

    MASKEY, DHIRAJ; KIM, HYUNG GUN; SUH, MYUNG-WHAN; ROH, GU SEOB; KIM, MYEUNG JU

    2014-01-01

    The increasing use of mobile communication has triggered an interest in its possible effects on the regulation of neurotransmitter signals. Due to the close proximity of mobile phones to hearing-related brain regions during usage, its use may lead to a decrease in the ability to segregate sounds, leading to serious auditory dysfunction caused by the prolonged exposure to radiofrequency (RF) radiation. The interplay among auditory processing, excitation and inhibitory molecule interactions plays a major role in auditory function. In particular, inhibitory molecules, such a glycine, are predominantly localized in the auditory brainstem. However, the effects of exposure to RF radiation on auditory function have not been reported to date. Thus, the aim of the present study was to investigate the effects of exposure to RF radiation on glycine receptor (GlyR) immunoreactivity (IR) in the auditory brainstem region at 835 MHz with a specific absorption rate of 4.0 W/kg for three months using free-floating immunohistochemistry. Compared with the sham control (SC) group, a significant loss of staining intensity of neuropils and cells in the different subdivisions of the auditory brainstem regions was observed in the mice exposed to RF radiation (E4 group). A decrease in the number of GlyR immunoreactive cells was also noted in the cochlear nuclear complex [anteroventral cochlear nucleus (AVCN), 31.09%; dorsal cochlear nucleus (DCN), 14.08%; posteroventral cochlear nucleus (PVCN), 32.79%] and the superior olivary complex (SOC) [lateral superior olivary nucleus (LSO), 36.85%; superior paraolivary nucleus (SPN), 24.33%, medial superior olivary nucleus (MSO), 23.23%; medial nucleus of the trapezoid body (MNTB), 10.15%] of the mice in the E4 group. Auditory brainstem response (ABR) analysis also revealed a significant threshold elevation of in the exposed (E4) group, which may be associated with auditory dysfunction. The present study suggests that the auditory brainstem region

  8. Effect of long-term exposure of 2.4 GHz radiofrequency radiation emitted from Wi-Fi equipment on testes functions.

    PubMed

    Dasdag, Suleyman; Taş, Muzaffer; Akdag, Mehmet Zulkuf; Yegin, Korkut

    2015-03-01

    The aim of this study was to investigate long-term effects of radiofrequency radiation (RFR) emitted from a Wireless Fidelity (Wi-Fi) system on testes. The study was carried out on 16 Wistar Albino adult male rats by dividing them into two groups such as sham (n: 8) and exposure (n: 8). Rats in the exposure group were exposed to 2.4 GHz RFR radiation for 24 h/d during 12 months (1 year). The same procedure was applied to the rats in the sham control group except the Wi-Fi system was turned off. Immediately after the last exposure, rats were sacrificed and reproductive organs were removed. Motility (%), concentration (×10(6)/mL), tail defects (%), head defects (%) and total morphologic defects (%) of sperms and weight of testes (g), left epididymis (g), prostate (g), seminal vesicles (g) were determined. Seminiferous tubules diameter (μm) and tunica albuginea thickness (μm) were also measured. However, the results were evaluated by using Johnsen's score. Head defects increased in the exposure group (p < 0.05) while weight of the epididymis and seminal vesicles, seminiferous tubules diameter and tunica albuginea thickness were decreased in the exposure group (p < 0.01, p < 0.001, p < 0.0001). However, other alterations of other parameters were not found significant (p > 0.05). In conclusion, we observed that long-term exposure of 2.4 GHz RF emitted from Wi-Fi (2420 μW/kg, 1 g average) affects some of the reproductive parameters of male rats. We suggest Wi-Fi users to avoid long-term exposure of RF emissions from Wi-Fi equipment. PMID:24460421

  9. Radiofrequency Ablation of Liver Tumors

    MedlinePlus

    ... Other equipment such as needle electrodes, an electrical generator and grounding pads may also be used. Radiofrequency ... retractable electrodes that extend when needed. The radiofrequency generator produces electrical currents in the range of radiofrequency ...

  10. Effects of 2. 45-GHz microwave and 100-MHz radiofrequency radiation on liposome permeability at the phase transition temperature

    SciTech Connect

    Liu, L.M.; Cleary, S.F.

    1988-01-01

    Large unilamellar dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) liposomes loaded with an aqueous chemotherapeutic drug, cytosine arabinofuranoside (ARA-C), were exposed for 30 min to 60 W/kg continuous-wave (CW) 100-MHz or 2.45-GHz radiation in vitro at temperatures between 37 degrees C and 43 degrees C. Liposomes were exposed in HEPES buffer or in HEPES buffer supplemented with 44% by volume fetal calf serum (FCS). Characteristic phase transition responses were detected in the range of 39 degrees C to 40 degrees C with the presence of FCS, increasing maximum % release of /sup 3/H-ARA-C by 20% relative to HEPES suspension. Neither frequency of electromagnetic radiation had any detectable effect on liposome permeability or the location of the phase transition in the presence or absence of FCS.

  11. Radiofrequency radiation hazard survey, 141 Tactical Control System, Ramey PR. Final report for period ending 29 March 1990

    SciTech Connect

    Montgomery, N.D.

    1990-05-01

    At the request of 156th TAC Clinic Bioenvironmental Engineer, AFOEHL personnel surveyed radio frequency radiation (RFR) hazards from the AN/TPS-43E transportable radar at the 141st Tactical Control Squadron, Ramey PR. During the survey, final installation checks were being performed on a new AN/FPS-93 radar, so a RFR hazard survey was performed on that unit as well. Measurements showed no hazard from either radar while the antennas are rotating. The AN/TPS-43E is mechanically interlocked so it will not radiate while the antenna is stopped. Operating instructions should specify immediate deactivation of the radar transmitter in case of interlock failure. The AN/FPS-93 will produce a hazard if the transmitter is operated while the antenna is stopped. The hazardous area is along the beam axis and is only accessible by persons climbing on the interior or exterior of the radome, or on the antenna structure itself. The unit Radiation Safety Officer should be notified when individuals are working on or in the radome to assure that they are not exposed to the direct beam of the radar. In the future, an AN/FPS-6 radar will be installed at the site. A theoretical evaluation is included which should be verified by direct measurement when operational.

  12. Radio-frequency measurements of coherent transition and Cherenkov radiation: Implications for high-energy neutrino detection

    SciTech Connect

    Gorham, Peter W.; Saltzberg, David P.; Schoessow, Paul; Gai, Wei; Power, John G.; Konecny, Richard; Conde, M. E.

    2000-12-01

    We report on measurements of (11--18)-cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator. The electrons were observed both in a configuration where they produced primarily transition radiation from an aluminum foil, and in a configuration designed for the electrons to produce Cherenkov radiation in a silica sand target. Our aim was to emulate the large electron excess expected to develop during an electromagnetic cascade initiated by an ultrahigh-energy particle. Such charge asymmetries are predicted to produce strong coherent radio pulses, which are the basis for several experiments to detect high-energy neutrinos from the showers they induce in Antarctic ice and in the lunar regolith. We detected coherent emission which we attribute both to transition and possibly Cherenkov radiation at different levels depending on the experimental conditions. We discuss implications for experiments relying on radio emission for detection of electromagnetic cascades produced by ultrahigh-energy neutrinos.

  13. Radio-frequency measurements of coherent transition and cherenkov radiation: implications for high-energy neutrino detection

    PubMed

    Gorham; Saltzberg; Schoessow; Gai; Power; Konecny; Conde

    2000-12-01

    We report on measurements of (11-18)-cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator. The electrons were observed both in a configuration where they produced primarily transition radiation from an aluminum foil, and in a configuration designed for the electrons to produce Cherenkov radiation in a silica sand target. Our aim was to emulate the large electron excess expected to develop during an electromagnetic cascade initiated by an ultrahigh-energy particle. Such charge asymmetries are predicted to produce strong coherent radio pulses, which are the basis for several experiments to detect high-energy neutrinos from the showers they induce in Antarctic ice and in the lunar regolith. We detected coherent emission which we attribute both to transition and possibly Cherenkov radiation at different levels depending on the experimental conditions. We discuss implications for experiments relying on radio emission for detection of electromagnetic cascades produced by ultrahigh-energy neutrinos. PMID:11138159

  14. Klebsiella pneumonia, a Microorganism that Approves the Non-linear Responses to Antibiotics and Window Theory after Exposure to Wi-Fi 2.4 GHz Electromagnetic Radiofrequency Radiation

    PubMed Central

    Taheri, M.; Mortazavi, S. M. J.; Moradi, M.; Mansouri, Sh.; Nouri, F.; Mortazavi, S. A. R.; Bahmanzadegan, F.

    2015-01-01

    Background Drug resistance is widely believed to be an increasingly serious threat to global public health. We have previously reported that short term exposure of microorganisms to diagnostic ultrasound waves could significantly alter their sensitivity to antibiotics. In our previous studies, Klebsiella pneumoniae showed major differences in the sensitivity to antibiotics in exposed and non-exposed samples. This study was aimed at investigating the alteration of antibiotic resistance of Klebsiella pneumonia, after exposure to Wi-Fi 2.4 GHz electromagnetic radiofrequency radiation. Materials and Methods In this in vitro study, three replicate agar plates were used for each test. The antibiotic susceptibility test was carried out using disc diffusion method on Mueller Hinton agar plates and the inhibition zones in both control and exposed groups were measured. A common Wi-Fi router was used in this study as the radiofrequency exposure source. Irradiated samples were exposed to Wi-Fi radiofrequency radiation for 3, 4.5 and 8 hours. Results Statistically significant variations of sensitivity to antibiotics were found for all studied antibiotics after 4.5 hours of RF exposure, compared to non-exposed bacteria. Interestingly, the mean diameters of the inhibition zones after 3 hours of exposure were less than those exposed for 4.5 hours. Following this rise in the sensitivity to antibiotics, a fall was observed in the bacteria exposed for 8 hours for all studied antibiotics. Conclusion The findings of this study show a statistically significant rise in the sensitivity of Klebsiella pneumoniae to different antibiotics after 4.5 hours of exposure to 2.4 GHz Wi-Fi radiation, followed by a fall after 8 hours of exposure. These observations can be interpreted by the concept of non-linearity in the responses of Klebsiella pneumoniae to different antibiotics after exposure to electromagnetic radiofrequency radiation. As in this study a minimum level of effect was needed for the

  15. Cooled radiofrequency ablation for bilateral greater occipital neuralgia.

    PubMed

    Vu, Tiffany; Chhatre, Akhil

    2014-01-01

    This report describes a case of bilateral greater occipital neuralgia treated with cooled radiofrequency ablation. The case is considered in relation to a review of greater occipital neuralgia, continuous thermal and pulsed radiofrequency ablation, and current medical literature on cooled radiofrequency ablation. In this case, a 35-year-old female with a 2.5-year history of chronic suboccipital bilateral headaches, described as constant, burning, and pulsating pain that started at the suboccipital region and radiated into her vertex. She was diagnosed with bilateral greater occipital neuralgia. She underwent cooled radiofrequency ablation of bilateral greater occipital nerves with minimal side effects and 75% pain reduction. Cooled radiofrequency ablation of the greater occipital nerve in challenging cases is an alternative to pulsed and continuous RFA to alleviate pain with less side effects and potential for long-term efficacy. PMID:24716017

  16. Nanoscale memristive radiofrequency switches

    NASA Astrophysics Data System (ADS)

    Pi, Shuang; Ghadiri-Sadrabadi, Mohammad; Bardin, Joseph C.; Xia, Qiangfei

    2015-06-01

    Radiofrequency switches are critical components in wireless communication systems and consumer electronics. Emerging devices include switches based on microelectromechanical systems and phase-change materials. However, these devices suffer from disadvantages such as large physical dimensions and high actuation voltages. Here we propose and demonstrate a nanoscale radiofrequency switch based on a memristive device. The device can be programmed with a voltage as low as 0.4 V and has an ON/OFF conductance ratio up to 1012 with long state retention. We measure the radiofrequency performance of the switch up to 110 GHz and demonstrate low insertion loss (0.3 dB at 40 GHz), high isolation (30 dB at 40 GHz), an average cutoff frequency of 35 THz and competitive linearity and power-handling capability. Our results suggest that, in addition to their application in memory and computing, memristive devices are also a leading contender for radiofrequency switch applications.

  17. Radiofrequency Ablation of Lung Tumors

    MedlinePlus

    ... computed tomography (CT) imaging, needle electrodes , an electrical generator and grounding pads are used. There are two ... retractable electrodes that extend when needed. The radiofrequency generator produces electrical currents in the range of radiofrequency ...

  18. Radiofrequency plasma antenna generated by femtosecond laser filaments in air

    SciTech Connect

    Brelet, Y.; Houard, A.; Point, G.; Prade, B.; Carbonnel, J.; Andre, Y.-B.; Mysyrowicz, A.; Arantchouk, L.; Pellet, M.

    2012-12-24

    We demonstrate tunable radiofrequency emission from a meter-long linear plasma column produced in air at atmospheric pressure. A short-lived plasma column is initially produced by femtosecond filamentation and subsequently converted into a long-lived discharge column by application of an external high voltage field. Radiofrequency excitation is fed to the plasma by induction and detected remotely as electromagnetic radiation by a classical antenna.

  19. Minimally Invasive Radiofrequency Devices.

    PubMed

    Sadick, Neil; Rothaus, Kenneth O

    2016-07-01

    This article reviews minimally invasive radiofrequency options for skin tightening, focusing on describing their mechanism of action and clinical profile in terms of safety and efficacy and presenting peer-reviewed articles associated with the specific technologies. Treatments offered by minimally invasive radiofrequency devices (fractional, microneedling, temperature-controlled) are increasing in popularity due to the dramatic effects they can have without requiring skin excision, downtime, or even extreme financial burden from the patient's perspective. Clinical applications thus far have yielded impressive results in treating signs of the aging face and neck, either as stand-alone or as postoperative maintenance treatments. PMID:27363771

  20. Radiofrequency (mobile telephones) Exposures and Health Risks: Findings and Controversies - Linet

    Cancer.gov

    Radiofrequency (mobile telephones) Exposures and Health Risks: Findings and Controversies by Dr. Martha Linet - part of the Radiation Epidemiology and Dosimetry Course on the health effects of radiation exposure

  1. Nanoscale memristive radiofrequency switches.

    PubMed

    Pi, Shuang; Ghadiri-Sadrabadi, Mohammad; Bardin, Joseph C; Xia, Qiangfei

    2015-01-01

    Radiofrequency switches are critical components in wireless communication systems and consumer electronics. Emerging devices include switches based on microelectromechanical systems and phase-change materials. However, these devices suffer from disadvantages such as large physical dimensions and high actuation voltages. Here we propose and demonstrate a nanoscale radiofrequency switch based on a memristive device. The device can be programmed with a voltage as low as 0.4 V and has an ON/OFF conductance ratio up to 10(12) with long state retention. We measure the radiofrequency performance of the switch up to 110 GHz and demonstrate low insertion loss (0.3 dB at 40 GHz), high isolation (30 dB at 40 GHz), an average cutoff frequency of 35 THz and competitive linearity and power-handling capability. Our results suggest that, in addition to their application in memory and computing, memristive devices are also a leading contender for radiofrequency switch applications. PMID:26108890

  2. Radiofrequency Ablation of Cancer

    PubMed Central

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2008-01-01

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized. PMID:15383844

  3. Radiofrequency Ablation of Cancer

    SciTech Connect

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2004-09-15

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized.

  4. Radiofrequency in cosmetic dermatology.

    PubMed

    Beasley, Karen L; Weiss, Robert A

    2014-01-01

    The demand for noninvasive methods of facial and body rejuvenation has experienced exponential growth over the last decade. There is a particular interest in safe and effective ways to decrease skin laxity and smooth irregular body contours and texture without downtime. These noninvasive treatments are being sought after because less time for recovery means less time lost from work and social endeavors. Radiofrequency (RF) treatments are traditionally titrated to be nonablative and are optimal for those wishing to avoid recovery time. Not only is there minimal recovery but also a high level of safety with aesthetic RF treatments. PMID:24267424

  5. Free radical release and HSP70 expression in two human immune-relevant cell lines after exposure to 1800 MHz radiofrequency radiation.

    PubMed

    Lantow, M; Schuderer, J; Hartwig, C; Simkó, M

    2006-01-01

    The goal of this study was to investigate whether radiofrequency (RF) electromagnetic-field (EMF) exposure at 1800 MHz causes production of free radicals and/or expression of heat-shock proteins (HSP70) in human immune-relevant cell systems. Human Mono Mac 6 and K562 cells were used to examine free radical release after exposure to incubator control, sham, RF EMFs, PMA, LPS, heat (40 degrees C) or co-exposure conditions. Several signals were used: continuous-wave, several typical modulations of the Global System for Mobile Communications (GSM): GSM-non DTX (speaking only), GSM-DTX (hearing only), GSM-Talk (34% speaking and 66% hearing) at specific absorption rates (SARs) of 0.5, 1.0, 1.5 and 2.0 W/kg. Heat and PMA treatment induced a significant increase in superoxide radical anions and in ROS production in the Mono Mac 6 cells when compared to sham and/or incubator conditions. No significant differences in free radical production were detected after RF EMF exposure or in the respective controls, and no additional effects on superoxide radical anion production were detected after co-exposure to RF EMFs+PMA or RF EMFs+LPS. The GSM-DTX signal at 2 W/kg produced a significant difference in free radical production when the data were compared to sham because of the decreasing sham value. This difference disappeared when data were compared to the incubator controls. To determine the involvement of heat-shock proteins as a possible inhibitor of free radical production, we investigated the HSP70 expression level after different RF EMF exposures; no significant effects were detected. PMID:16392966

  6. Radiofrequency attenuator and method

    DOEpatents

    Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.; Agrawal, Anoop; Hall, Simon B.

    2009-01-20

    Radiofrequency attenuator and method. The attenuator includes a pair of transparent windows. A chamber between the windows is filled with molten salt. Preferred molten salts include quarternary ammonium cations and fluorine-containing anions such as tetrafluoroborate (BF.sub.4.sup.-), hexafluorophosphate (PF.sub.6.sup.-), hexafluoroarsenate (AsF.sub.6.sup.-), trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Radicals or radical cations may be added to or electrochemically generated in the molten salt to enhance the RF attenuation.

  7. Radiofrequency attenuator and method

    DOEpatents

    Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.; Agrawal, Anoop; Hall, Simon B.

    2009-11-10

    Radiofrequency attenuator and method. The attenuator includes a pair of transparent windows. A chamber between the windows is filled with molten salt. Preferred molten salts include quarternary ammonium cations and fluorine-containing anions such as tetrafluoroborate (BF.sub.4.sup.-), hexafluorophosphate (PF.sub.6.sup.-), hexafluoroarsenate (AsF.sub.6.sup.-), trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3 C.sup.-). Radicals or radical cations may be added to or electrochemically generated in the molten salt to enhance the RF attenuation.

  8. Superconducting radiofrequency window assembly

    DOEpatents

    Phillips, H.L.; Elliott, T.S.

    1997-03-11

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly has a superconducting metal-ceramic design. The srf window assembly comprises a superconducting frame, a ceramic plate having a superconducting metallized area, and a superconducting eyelet for sealing plate into frame. The plate is brazed to eyelet which is then electron beam welded to frame. A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator. 11 figs.

  9. Superconductive radiofrequency window assembly

    DOEpatents

    Phillips, H.L.; Elliott, T.S.

    1998-05-19

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The SRF window assembly has a superconducting metal-ceramic design. The SRF window assembly comprises a superconducting frame, a ceramic plate having a superconducting metallized area, and a superconducting eyelet for sealing plate into frame. The plate is brazed to eyelet which is then electron beam welded to frame. A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the SRF window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator. 11 figs.

  10. Radiofrequency Ablation Therapy for Solid Tumors

    SciTech Connect

    Kam, Anthony

    2002-12-04

    Surgical resection, systemic chemotherapy, and local radiation have been the conventional treatments for localized solid cancer. Because certain patients are not candidates for tumor resection and because many tumors are poorly responsive to chemotherapy and radiation, there has been an impetus to develop alternative therapies. Radiofrequency ablation (RFA) is a minimally invasive therapy for localized solid cancers that has gained considerable attention in the last 12 years. Advantages of minimally invasive therapies over surgery include less recovery time, lower morbidity and mortality, eligibility of more patients, and lower cost. RFA has been applied most extensively to inoperable hepatic tumors. It is investigational for tumors in the kidney, lung, bone, breast, and adrenal gland. This colloquium will review the mechanism, techniques, limitations, and clinical applications of RFA. The ultimate role that RFA will play in cancer therapy will depend on the results of long-term follow-up and prospective randomized trials.

  11. Biplanar Radiofrequency Coil Design

    NASA Astrophysics Data System (ADS)

    Roberts, D. A.; Insko, E. K.; Bolinger, L.; Leigh, J. S.

    A novel geometry for radiofrequency coil design is described. In this geometry, longitudinal wires of the coil lie on two parallel planes. The currents in the wires of one plane run in the direction opposite to those of the other plane. An analytic solution is provided for the field produced by infinite surface currents running in the biplanar geometry. For the case of discrete wires, computer-generated field maps imply that the homogeneity and sensitivity of the biplanar design are superior to those of a saddle coil, but worse than those obtained in an equivalent discrete cosine or birdcage coil design. Optimization of this coil design was performed using computer simulations. The measured B1 map of an optimized, single-tuned biplanar coil compares favorably to that of an equivalent discrete cosine coil, demonstrating excellent homogeneity in the central region of the coil. A 30 × 24 × 40 cm biplanar coil has been coupled to a 1.5 T imaging system. Images of the human abdomen generated with this coil demonstrate a high degree of homogeneity across nearly all of the sensitive region of the coil.

  12. Superconductive radiofrequency window assembly

    DOEpatents

    Phillips, Harry Lawrence; Elliott, Thomas S.

    1998-01-01

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly (20) has a superconducting metal-ceramic design. The srf window assembly (20) comprises a superconducting frame (30), a ceramic plate (40) having a superconducting metallized area, and a superconducting eyelet (50) for sealing plate (40) into frame (30). The plate (40) is brazed to eyelet (50) which is then electron beam welded to frame (30). A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator.

  13. Superconducting radiofrequency window assembly

    DOEpatents

    Phillips, Harry L.; Elliott, Thomas S.

    1997-01-01

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly (20) has a superconducting metal-ceramic design. The srf window assembly (20) comprises a superconducting frame (30), a ceramic plate (40) having a superconducting metallized area, and a superconducting eyelet (50) for sealing plate (40) into frame (30). The plate (40) is brazed to eyelet (50) which is then electron beam welded to frame (30). A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator.

  14. Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation using Superconducting Tunnel Junctions with Radio-Frequency Single-Electron Transistors

    NASA Technical Reports Server (NTRS)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Wollack, E. J.; Schoelkopf, R. J.; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    The science drivers for the SPIRIT/SPECS missions demand sensitive, fast, compact, low-power, large-format detector arrays for high resolution imaging and spectroscopy in the far infrared and submillimeter. Detector arrays with 10,000 pixels and sensitivity less than 10(exp 20)-20 W/Hz(exp 20)0.5 are needed. Antenna-coupled superconducting tunnel junction detectors with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique when forming arrays. The device consists of an antenna structure to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure currents through tunnel junction contacts to the absorber volume. We will describe optimization of device parameters, and recent results on fabrication techniques for producing devices with high yield for detector arrays. We will also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

  15. Light modulated electron beam driven radiofrequency emitter

    DOEpatents

    Wilson, M.T.; Tallerico, P.J.

    1979-10-10

    The disclosure relates to a light modulated electron beam-driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

  16. New-generation radiofrequency technology.

    PubMed

    Krueger, Nils; Sadick, Neil S

    2013-01-01

    Radiofrequency (RF) technology has become a standard treatment in aesthetic medicine with many indications due to its versatility, efficacy, and safety. It is used worldwide for cellulite reduction; acne scar revision; and treatment of hypertrophic scars and keloids, rosacea, and inflammatory acne in all skin types. However, the most common indication for RF technology is the nonablative tightening of tissue to improve skin laxity and reduce wrinkles. Radiofrequency devices are classified as unipolar, bipolar, or multipolar depending on the number of electrodes used. Additional modalities include fractional RF; sublative RF; phase-controlled RF; and combination RF therapies that apply light, massage, or pulsed electromagnetic fields (PEMFs). This article reviews studies and case series on these devices. Radiofrequency technology for aesthetic medicine has seen rapid advancements since it was used for skin tightening in 2003. Future developments will continue to keep RF technology at the forefront of the dermatologist's armamentarium for skin tightening and rejuvenation. PMID:23461058

  17. Emerging indications of endoscopic radiofrequency ablation

    PubMed Central

    Becq, Aymeric; Camus, Marine; Rahmi, Gabriel; de Parades, Vincent; Marteau, Philippe

    2015-01-01

    Introduction Radiofrequency ablation (RFA) is a well-validated treatment of dysplastic Barrett's esophagus. Other indications of endoscopic RFA are under evaluation. Results Four prospective studies (total 69 patients) have shown that RFA achieved complete remission of early esophageal squamous intra-epithelial neoplasia at a rate of 80%, but with a substantial risk of stricture. In the setting of gastric antral vascular ectasia, two prospective monocenter studies, and a retrospective multicenter study, (total 51 patients), suggest that RFA is efficacious in terms of reducing transfusion dependency. In the setting of chronic hemorrhagic radiation proctopathy, a prospective monocenter study and a retrospective multicenter study (total 56 patients) suggest that RFA is an efficient treatment. A retrospective comparative study (64 patients) suggests that RFA improves stents patency in malignant biliary strictures. Conclusions Endoscopic RFA is an upcoming treatment modality in early esophageal squamous intra-epithelial neoplasia, as well as in gastric, rectal, and biliary diseases. PMID:26279839

  18. Microwave Radiation Detector

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.

    1984-01-01

    Direct photon detector responds to microwave frequencies. Method based on trapped-ion frequency-generation standards proposed to detect radio-frequency (RF) radiation at 40.5 GHz. Technique used for directdetection (RF) communication, radar, and radio astronomy.

  19. Bray-Liebhafsky oscillatory reaction in the radiofrequency electromagnetic field

    NASA Astrophysics Data System (ADS)

    Stanisavljev, Dragomir R.; Velikić, Zoran; Veselinović, Dragan S.; Jacić, Nevena V.; Milenković, Maja C.

    2014-09-01

    Oscillatory Bray-Liebhafsky (BL) reaction is capacitively coupled with the electromagnetic radiation in the frequency range 60-110 MHz. Because of the specific reaction dynamics characterized by several characteristic parameters (induction period, period between chemical oscillations and their amplitude) it served as a good model system for the investigation of the effects of radiofrequent (RF) radiation. RF power of up to 0.2 W did not produce observable changes of the BL reaction parameters in the limit of the experiment reproductivity. Results indicate that, under the given experimental conditions, both dissipative and reactive properties of the solution are not considerably coupled with the RF electrical field.

  20. Addressed qubit manipulation in radio-frequency dressed lattices

    NASA Astrophysics Data System (ADS)

    Sinuco-León, G. A.; Garraway, B. M.

    2016-03-01

    Precise control over qubits encoded as internal states of ultracold atoms in arrays of potential wells is a key element for atomtronics applications in quantum information, quantum simulation and atomic microscopy. Here we theoretically study atoms trapped in an array of radio-frequency dressed potential wells and propose a scheme for engineering fast and high-fidelity single-qubit gates with low error due to cross-talk. In this proposal, atom trapping and qubit manipulation relies exclusively on long-wave radiation making it suitable for atom-chip technology. We demonstrate that selective qubit addressing with resonant microwaves can be programmed by controlling static and radio-frequency currents in microfabricated conductors. These results should enable studies of neutral-atom quantum computing architectures, powered by low-frequency electromagnetic fields with the benefit of simple schemes for controlling individual qubits in large ensembles.

  1. Continuous Cavitation Designed for Enhancing Radiofrequency Ablation via a Special Radiofrequency Solidoid Vaporization Process.

    PubMed

    Zhang, Kun; Li, Pei; Chen, Hangrong; Bo, Xiaowan; Li, Xiaolong; Xu, Huixiong

    2016-02-23

    Lowering power output and radiation time during radiofrequency (RF) ablation is still a challenge. Although it is documented that metal-based magnetothermal conversion and microbubbles-based inertial cavitation have been tried to overcome above issues, disputed toxicity and poor magnetothermal conversion efficiency for metal-based nanoparticles and violent but transient cavitation for microbubbles are inappropriate for enhancing RF ablation. In this report, a strategy, i.e., continuous cavitation, has been proposed, and solid menthol-encapsulated poly lactide-glycolide acid (PLGA) nanocapsules have been constructed, as a proof of concept, to validate the role of such a continuous cavitation principle in continuously enhancing RF ablation. The synthesized PLGA-based nanocapsules can respond to RF to generate menthol bubbles via distinctive radiofrequency solidoid vaporization (RSV) process, meanwhile significantly enhance ultrasound imaging for HeLa solid tumor, and further facilitate RF ablation via the continuous cavitation, as systematically demonstrated both in vitro and in vivo. Importantly, this RSV strategy can overcome drawbacks and limitations of acoustic droplet vaporization (ADV) and optical droplet vaporization (ODV), and will probably find broad applications in further cancer theranostics. PMID:26800221

  2. Directional Radio-Frequency Identification Tag Reader

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J.; Taylor, John D.; Henderson, John J.

    2004-01-01

    A directional radio-frequency identification (RFID) tag reader has been designed to facilitate finding a specific object among many objects in a crowded room. The device could be an adjunct to an electronic inventory system that tracks RFID-tagged objects as they move through reader-equipped doorways. Whereas commercial RFID-tag readers do not measure directions to tagged objects, the device is equipped with a phased-array antenna and a received signal-strength indicator (RSSI) circuit for measuring direction. At the beginning of operation, it is set to address only the RFID tag of interest. It then continuously transmits a signal to interrogate that tag while varying the radiation pattern of the antenna. It identifies the direction to the tag as the radiation pattern direction of peak strength of the signal returned by the tag. An approximate distance to the tag is calculated from the peak signal strength. The direction and distance can be displayed on a screen. A prototype containing a Yagi antenna was found to be capable of detecting a 915.5-MHz tag at a distance of approximately equal to 15 ft (approximately equal to 4.6 m).

  3. Radiofrequency Physics for Minimally Invasive Aesthetic Surgery.

    PubMed

    Levy, Adam S; Grant, Robert T; Rothaus, Kenneth O

    2016-07-01

    Radiofrequency energy has a wide range of medical applications, including noninvasive treatment of wrinkles and body contouring. This technology works by differential heating of skin and soft tissue layers causing dermal remodeling or adipolysis, ultimately leading to observable effects. This article reviews the physics of radiofrequency as applied clinically. PMID:27363769

  4. Aesthetic Applications of Radiofrequency Devices.

    PubMed

    Sadick, Neil; Rothaus, Kenneth O

    2016-07-01

    Radiofrequency (RF)-based devices are used to improve face and neck laxity, a major feature of aging that until recently could only be addressed with surgery. Although these treatments are not meant to replace surgical procedures, patient satisfaction studies have been consistently high. For physicians offering these skin rejuvenation procedures, it is essential to have intimate knowledge of how the devices work, select appropriate candidates, set realistic expectations, and combine treatments to optimize outcomes. This article discusses the various noninvasive RF technologies currently in use and reviews pertinent clinical studies evaluating their efficacy and safety. PMID:27363770

  5. Band-selective radiofrequency pulses

    NASA Astrophysics Data System (ADS)

    Geen, Helen; Freeman, Ray

    A theoretical treatment is given of the general problem of designing amplitude-modulated radiofrequency pulses that will excite a specified band of frequencies within a high-resolution NMR spectrum with uniform intensity and phase but with negligible excitation elsewhere. First a trial pulse envelope is defined in terms of a finite Fourier series and its frequency-domain profile calculated through the Bloch equations. The result is compared with the desired target profile to give a multidimensional error surface. The method of simulated annealing is then used to find the global minimum on this surface and the result refined by standard gradient-descent optimization. In this manner, a family of new shaped radio-frequency pulses, known as BURP ( band-selective, uniform response, pure-phase) pulses, has been created. These are of two classes—pulses that excite or invert z magnetization and those that act as general-rotation πr/2 or π pulses irrespective of the initial condition of the nuclear magnetization. It was found convenient to design the latter class as amplitude-modulated time-symmetric pulses. Tables of Fourier coefficients and pulse-shape ordinates are given for practical implementation of BURP pulses, together with the calculated frequency-domain responses and experimental verifications. Examples of the application of band-selective pulses in conventional and multidimensional spectroscopy are given. Pure-phase pulses of this type should also find applications in magnetic resonance imaging where refocusing schemes are undesirable.

  6. Radiofrequency Ablation of Metastatic Pheochromocytoma

    PubMed Central

    Venkatesan, Aradhana M.; Locklin, Julia; Lai, Edwin W.; Adams, Karen T.; Fojo, Antonio Tito; Pacak, Karel; Wood, Bradford J.

    2013-01-01

    In the present report on the preliminary safety and effectiveness of radiofrequency (RF) ablation for pheochromocytoma metastases, seven metastases were treated in six patients (mean size, 3.4 cm; range, 2.2–6 cm). α- and β-adrenergic and catecholamine synthesis inhibition and intraprocedural anesthesia monitoring were used. Safety was assessed by recording ablation-related complications. Complete ablation was defined as a lack of enhancement within the ablation zone on follow-up computed tomography. No serious adverse sequelae were observed. Complete ablation was achieved in six of seven metastases (mean follow-up, 12.3 months; range, 2.5–28 months). In conclusion, RF ablation may be safely performed for metastatic pheochromocytoma given careful attention to peri-procedural management. PMID:19875067

  7. Trigeminal Neuralgia and Radiofrequency Lesioning

    PubMed Central

    Eugene, Andy R.

    2016-01-01

    Trigeminal Neuralgia is a disorder that is characterized with electrical-type shocking pain in the face and jaw. This pain may either present as sharp unbearable pain unilateral or bilaterally. There is no definite etiology for this condition. There are various treatment methods that are currently being used to relieve the pain. One of the pharmacological treatments is Carbamazepine and the most prevalent surgical treatments include Gamma Knife Surgery (GKS), Microvascular Decompression (MVD) and Radiofrequency Lesioning (RFL). Although, MVD is the most used surgical method it is not an option for all the patients due to the intensity of the procedure. RFL is used when MVD is not suitable. In this paper we present the various options in the treatment of Trigeminal Neuralgia. PMID:26770820

  8. Adaptive Response in Animals Exposed to Non-Ionizing Radiofrequency Fields: Some Underlying Mechanisms

    PubMed Central

    Cao, Yi; Tong, Jian

    2014-01-01

    During the last few years, our research group has been investigating the phenomenon of adaptive response in animals exposed to non-ionizing radiofrequency fields. The results from several separate studies indicated a significant increase in survival, decreases in genetic damage as well as oxidative damage and, alterations in several cellular processes in mice pre-exposed to radiofrequency fields and subsequently subjected to sub-lethal or lethal doses of γ-radiation or injected with bleomycin, a radiomimetic chemical mutagen. These observations indicated the induction of adaptive response providing the animals the ability to resist subsequent damage. Similar studies conducted by independent researchers in mice and rats have supported our observation on increased survival. In this paper, we have presented a brief review of all of our own and other independent investigations on radiofrequency fields-induced adaptive response and some underlying mechanisms discussed. PMID:24758897

  9. Non-invasive radiofrequency ablation of malignancies mediated by quantum dots, gold nanoparticles and carbon nanotubes

    PubMed Central

    Glazer, Evan S; Curley, Steven A

    2013-01-01

    Various types of nanoparticles efficiently heat in radiofrequency fields, which can potentially be used to produce cancer cell cytotoxicity within minutes. Multifunctional and targeted nanoparticles have demonstrated effective cancer control in vivo without significant toxicity associated with radiofrequency field exposure. Importantly, animals treated systemically with targeted nanoparticles smaller than 50 nm demonstrate tumor necrosis after radiofrequency field exposure without acute or chronic toxicity to normal tissues. Likewise, the future holds great promise for multifunctional imaging as well as multimodality therapy with chemotherapeutic molecules and ionizing radiation sensitizing agents attached to nanoparticle constructs. However, the appropriate balance of safety and efficacy for diagnosis, therapy, and therapeutic monitoring with these nanoparticles remains to be fully elucidated. PMID:22826886

  10. Esophageal papilloma: Flexible endoscopic ablation by radiofrequency

    PubMed Central

    del Genio, Gianmattia; del Genio, Federica; Schettino, Pietro; Limongelli, Paolo; Tolone, Salvatore; Brusciano, Luigi; Avellino, Manuela; Vitiello, Chiara; Docimo, Giovanni; Pezzullo, Angelo; Docimo, Ludovico

    2015-01-01

    Squamous papilloma of the esophagus is a rare benign lesion of the esophagus. Radiofrequency ablation is an established endoscopic technique for the eradication of Barrett esophagus. No cases of endoscopic ablation of esophageal papilloma by radiofrequency ablation (RFA) have been reported. We report a case of esophageal papilloma successfully treated with a single session of radiofrequency ablation. Endoscopic ablation of the lesion was achieved by radiofrequency using a new catheter inserted through the working channel of endoscope. The esophageal ablated tissue was removed by a specifically designed cup. Complete ablation was confirmed at 3 mo by endoscopy with biopsies. This case supports feasibility and safety of as a new potential indication for BarrxTM RFA in patients with esophageal papilloma. PMID:25789102

  11. Radiofrequency quadrupole accelerators and their applications

    SciTech Connect

    Stokes, R.H.; Wangler, T.P.

    1988-01-01

    This review of Radiofrequency Quadrupole (RFQ) Acelerators contains a short history of Soviet and Los Alamos RFQ developments, RFQ beam dynamics, resonator structures, and the characteristics and performance of RFQ accelerators. (AIP)

  12. Radiofrequency ablation for hepatocellular carcinoma.

    PubMed

    Nishikawa, Hiroki; Kimura, Toru; Kita, Ryuichi; Osaki, Yukio

    2013-09-01

    Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related mortality worldwide. Unfortunately, only 20% of HCC patients are amenable to curative therapy (liver transplantation or surgical resection). Locoregional therapies such as radiofrequency ablation (RFA), percutaneous ethanol injection, microwave coagulation therapy, and transcatheter arterial chemoembolisation play a key role in the management of HCC. The choice of the treatment modality depends on the size of the tumour, tumour location, anatomic considerations and the number of tumours present and liver function. RFA therapy for HCC can be performed safely using a percutaneous, laparoscopic, or an open approach, even in patients with poor functional reserve. Since the introduction of RFA, several randomised controlled trials and non-randomised studies comparing RFA and other therapies for HCC have been conducted. In addition, in the last decade there have been technical advances in RFA therapy for HCC, resulting in significant improvement in the prognosis of HCC patients treated with this modality. In this review, we primarily focus on percutaneous RFA therapy for HCC and refer to current knowledge and future perspectives for this therapy. We also discuss new emerging ablation techniques. PMID:23937321

  13. Percutaneous Tumor Ablation with Radiofrequency

    PubMed Central

    Wood, Bradford J.; Ramkaransingh, Jeffrey R.; Fojo, Tito; Walther, McClellan M.; Libutti, Stephen K.

    2008-01-01

    BACKGROUND Radiofrequency thermal ablation (RFA) is a new minimally invasive treatment for localized cancer. Minimally invasive surgical options require less resources, time, recovery, and cost, and often offer reduced morbidity and mortality, compared with more invasive methods. To be useful, image-guided, minimally invasive, local treatments will have to meet those expectations without sacrificing efficacy. METHODS Image-guided, local cancer treatment relies on the assumption that local disease control may improve survival. Recent developments in ablative techniques are being applied to patients with inoperable, small, or solitary liver tumors, recurrent metachronous hereditary renal cell carcinoma, and neoplasms in the bone, lung, breast, and adrenal gland. RESULTS Recent refinements in ablation technology enable large tumor volumes to be treated with image-guided needle placement, either percutaneously, laparoscopically, or with open surgery. Local disease control potentially could result in improved survival, or enhanced operability. CONCLUSIONS Consensus indications in oncology are ill-defined, despite widespread proliferation of the technology. A brief review is presented of the current status of image-guided tumor ablation therapy. More rigorous scientific review, long-term follow-up, and randomized prospective trials are needed to help define the role of RFA in oncology. PMID:11900230

  14. The radiofrequency magnetic dipole discharge

    NASA Astrophysics Data System (ADS)

    Martines, E.; Zuin, M.; Marcante, M.; Cavazzana, R.; Fassina, A.; Spolaore, M.

    2016-05-01

    This paper describes a novel and simple concept of plasma source, which is able to produce a radiofrequency magnetized discharge with minimal power requirements. The source is based on the magnetron concept and uses a permanent magnet as an active electrode. The dipolar field produced by the magnet confines the electrons, which cause further ionization, thus producing a toroidally shaped plasma in the equatorial region around the electrode. A plasma can be ignited with such scheme with power levels as low as 5 W. Paschen curves have been built for four different working gases, showing that in Helium or Neon, plasma breakdown is easily obtained also at atmospheric pressure. The plasma properties have been measured using a balanced Langmuir probe, showing that the electron temperature is around 3-4 eV and higher in the cathode proximity. Plasma densities of the order of 1016 m-3 have been obtained, with a good positive scaling with applied power. Overall, the electron pressure appears to be strongly correlated with the magnetic field magnitude in the measurement point.

  15. 21 CFR 882.4725 - Radiofrequency lesion probe.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... (a) Identification. A radiofrequency lesion probe is a device connected to a radiofrequency (RF) lesion generator to deliver the RF energy to the site within the nervous system where a lesion is...

  16. 21 CFR 882.4725 - Radiofrequency lesion probe.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... (a) Identification. A radiofrequency lesion probe is a device connected to a radiofrequency (RF) lesion generator to deliver the RF energy to the site within the nervous system where a lesion is...

  17. 21 CFR 882.4725 - Radiofrequency lesion probe.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... (a) Identification. A radiofrequency lesion probe is a device connected to a radiofrequency (RF) lesion generator to deliver the RF energy to the site within the nervous system where a lesion is...

  18. 21 CFR 882.4725 - Radiofrequency lesion probe.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... (a) Identification. A radiofrequency lesion probe is a device connected to a radiofrequency (RF) lesion generator to deliver the RF energy to the site within the nervous system where a lesion is...

  19. 47 CFR 2.801 - Radiofrequency device defined.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MATTERS; GENERAL RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.801 Radiofrequency device..., but are not limited to: (a) The various types of radio communication transmitting devices...

  20. 47 CFR 2.801 - Radiofrequency device defined.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Radiofrequency device defined. 2.801 Section 2.801 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.801 Radiofrequency device defined. As used in this part,...

  1. 47 CFR 2.801 - Radiofrequency device defined.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Radiofrequency device defined. 2.801 Section 2.801 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.801 Radiofrequency device defined. As used in this part,...

  2. 47 CFR 2.801 - Radiofrequency device defined.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Radiofrequency device defined. 2.801 Section 2.801 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.801 Radiofrequency device defined. As used in this part,...

  3. 47 CFR 2.801 - Radiofrequency device defined.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Radiofrequency device defined. 2.801 Section 2.801 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.801 Radiofrequency device defined. As used in this part,...

  4. Radiofrequency ablation technique eradicating palpebral margin neoplasm

    PubMed Central

    Jiang, Tian-Yu; Wang, Xing-Lin; Suo, Wei; He, Qing-Hua; Xiao, Hong-Yu

    2011-01-01

    AIM To report the study on radiofrequency ablation technique for eradication of palpebral margin neoplasm and its clinical effects. METHODS One hundred and six cases with the palpebral margin neoplasm were performed surgical removal with radiofrequency ablation technique. The 1-2 months postoperative follow-up was investigated and the lost cases were excluded from statistics. The continuing follow-up lasted about 6-16months. RESULTS One hundred cases underwent one treatment and 6 cases underwent two treatments. Six cases were missed. All the cases followed up healed well without pigmentation or scar left, nor eyelash loss or palpebral margin deformation. No case was recurrent. CONCLUSION Radiofrequency ablation has significant efficiency in eradicating the palpebral margin neoplasm. PMID:22553639

  5. Anthropogenic radiofrequency electromagnetic fields as an emerging threat to wildlife orientation.

    PubMed

    Balmori, Alfonso

    2015-06-15

    The rate of scientific activity regarding the effects of anthropogenic electromagnetic radiation in the radiofrequency (RF) range on animals and plants has been small despite the fact that this topic is relevant to the fields of experimental biology, ecology and conservation due to its remarkable expansion over the past 20 years. Current evidence indicates that exposure at levels that are found in the environment (in urban areas and near base stations) may particularly alter the receptor organs to orient in the magnetic field of the earth. These results could have important implications for migratory birds and insects, especially in urban areas, but could also apply to birds and insects in natural and protected areas where there are powerful base station emitters of radiofrequencies. Therefore, more research on the effects of electromagnetic radiation in nature is needed to investigate this emerging threat. PMID:25747364

  6. Percutaneous Radiofrequency Ablation for Treatment of Recurrent Retroperitoneal Liposarcoma

    SciTech Connect

    Keil, Sebastian Bruners, Philipp; Brehmer, Bernhard; Mahnken, Andreas Horst

    2008-07-15

    Percutaneous CT-guided radiofrequency ablation (RFA) is becoming more and more established in the treatment of various neoplasms, including retroperitoneal tumors of the kidneys and the adrenal glands. We report the case of RFA in a patient suffering from the third relapse of a retroperitoneal liposarcoma in the left psoas muscle. After repeated surgical resection and supportive radiation therapy of a primary retroperitoneal liposarcoma and two surgically treated recurrences, including replacement of the ureter by a fraction of the ileum, there was no option for further surgery. Thus, we considered RFA as the most suitable treatment option. Monopolar RFA was performed in a single session with a 2-cm umbrella-shaped LeVeen probe. During a 27-month follow-up period the patient remained free of tumor.

  7. Multiplexed infrared photodetection using resonant radio-frequency circuits

    NASA Astrophysics Data System (ADS)

    Liu, R.; Lu, R.; Roberts, C.; Gong, S.; Allen, J. W.; Allen, M. S.; Wenner, B. R.; Wasserman, D.

    2016-02-01

    We demonstrate a room-temperature semiconductor-based photodetector where readout is achieved using a resonant radio-frequency (RF) circuit consisting of a microstrip split-ring resonator coupled to a microstrip busline, fabricated on a semiconductor substrate. The RF resonant circuits are characterized at RF frequencies as function of resonator geometry, as well as for their response to incident IR radiation. The detectors are modeled analytically and using commercial simulation software, with good agreement to our experimental results. Though the detector sensitivity is weak, the detector architecture offers the potential for multiplexing arrays of detectors on a single read-out line, in addition to high speed response for either direct coupling of optical signals to RF circuitry, or alternatively, carrier dynamics characterization of semiconductor, or other, material systems.

  8. Managing turbinate hypertrophy: coblation vs. radiofrequency treatment.

    PubMed

    Passali, D; Loglisci, M; Politi, L; Passali, G C; Kern, E

    2016-06-01

    The role of inferior turbinate hypertrophy in the reduction of nasal airflow is well established. Although chronic nasal obstruction is not life- threatening, it significantly impairs patients' quality of life, affecting many aspects of daily activities; therefore, patients seek medical intervention. 40 patients were selected (27 males and 13 females) between 27 and 64 years of age with a symptom of nasal obstruction. The patients were divided in two groups: Group 1: coblation, 25 patients (18 males and 7 females); Group 2: radiofrequency, 15 patients (7 males and 6 females). These 40 patients were followed for 3 years. Patients were analyzed using both subjective and objective methods. The visual analog scale (VAS) subjective data and objective data including both active anterior rhinomanometry and acoustic rhinometry were recorded and analyzed. Data were collected pre-operatively and at 1 and 3 years post-operatively. According to our data, both coblation and radiofrequency turbinate reduction benefit patients with good results. The complications, found during the follow-up, are limited to minimal bleeding and crusting. Coblation and radiofrequency were significantly less painful than others procedures during the early post-operative period. In our study, both coblation and radiofrequency provide an improvement in nasal airflow with a reduction in nasal obstructive symptoms in the short term, but their efficacy tended to decrease within 3 years. PMID:26321749

  9. Assessment of outdoor radiofrequency electromagnetic field exposure through hotspot localization using kriging-based sequential sampling.

    PubMed

    Aerts, Sam; Deschrijver, Dirk; Verloock, Leen; Dhaene, Tom; Martens, Luc; Joseph, Wout

    2013-10-01

    In this study, a novel methodology is proposed to create heat maps that accurately pinpoint the outdoor locations with elevated exposure to radiofrequency electromagnetic fields (RF-EMF) in an extensive urban region (or, hotspots), and that would allow local authorities and epidemiologists to efficiently assess the locations and spectral composition of these hotspots, while at the same time developing a global picture of the exposure in the area. Moreover, no prior knowledge about the presence of radiofrequency radiation sources (e.g., base station parameters) is required. After building a surrogate model from the available data using kriging, the proposed method makes use of an iterative sampling strategy that selects new measurement locations at spots which are deemed to contain the most valuable information-inside hotspots or in search of them-based on the prediction uncertainty of the model. The method was tested and validated in an urban subarea of Ghent, Belgium with a size of approximately 1 km2. In total, 600 input and 50 validation measurements were performed using a broadband probe. Five hotspots were discovered and assessed, with maximum total electric-field strengths ranging from 1.3 to 3.1 V/m, satisfying the reference levels issued by the International Commission on Non-Ionizing Radiation Protection for exposure of the general public to RF-EMF. Spectrum analyzer measurements in these hotspots revealed five radiofrequency signals with a relevant contribution to the exposure. The radiofrequency radiation emitted by 900 MHz Global System for Mobile Communications (GSM) base stations was always dominant, with contributions ranging from 45% to 100%. Finally, validation of the subsequent surrogate models shows high prediction accuracy, with the final model featuring an average relative error of less than 2dB (factor 1.26 in electric-field strength), a correlation coefficient of 0.7, and a specificity of 0.96. PMID:23759207

  10. Radio-frequency heating of the coronal plasma during flares

    NASA Technical Reports Server (NTRS)

    Melrose, D. B.; Dulk, G. A.

    1984-01-01

    A model is developed for the radio-frequency (RF) heating of soft X-ray emitting plasma in solar flares due to absorption of amplified cyclotron radiation. The radiation, carrying approximately 10 to the 27th to approximately 10 to the 30th erg/s, is generated through maser emission following partial precipitation of electrons in one or more flaring loops. The maser operates in a large number of small regions, each producing an 'elementary burst' (EB) of short duration. This radiation propagates either directly or after reflection to the second-harmonic absorption layer, where it is absorbed by thermal electrons. The properties of EBs and the heating of the electrons in the absorption layer are discussed in detail. RF heating and evaporation models for the production of soft X-ray emitting plasma are compared. Properties of the RF heating model that explain observed features are energy transport across field lines, rapid heating (in approximately 1 s) of coronal plasma to approximately 3 x 10 to the 7th K, and instigation of turbulent velocities up to the ion sound speed.

  11. The optimal radiofrequency temperature in radiofrequency thermocoagulation for idiopathic trigeminal neuralgia

    PubMed Central

    Tang, Yuan-Zhang; Yang, Li-Qiang; Yue, Jian-Ning; Wang, Xiao-Ping; HE, Liang-Liang; NI, Jia-Xiang

    2016-01-01

    Abstract Objective: Our previous study evaluated the effectiveness and safety of radiofrequency thermocoagulation (RFT) of trigeminal gasserian ganglion for idiopathic trigeminal neuralgia (ITN). The aim of this study was to evaluate the optimal radiofrequency temperature of computed tomography (CT)-guided RFT for treatment of ITN. Methods: A retrospective study of patients with ITN treated with a single CT-guided RFT procedure between January 2002 and December 2013. Patients were divided into ≤75 °C, 75 °C, and ≥80 °C groups according to the highest radiofrequency temperature used. Pain relief was graded from poor to excellent, and facial numbness/dysesthesia from I (absent) to IV (most severe). Results: A total of 1161 RFT procedures were undertaken in the 1137 patients. The mean follow-up time was 46 ± 31 months. There were no significant differences in the rate of excellent pain relief according to the radiofrequency temperature used. However, more patients experienced with no facial numbness or facial numbness gradually resolved and those patients treated at 75 °C had a lower rate of grade IV facial numbness/dysesthesia than other groups. Conclusions: The optimal radiofrequency temperature to maximize pain relief and minimize facial numbness or dysesthesia may be 75 °C, but this requires confirmation. PMID:27428194

  12. Health implications of exposure to radiofrequency/microwave energies

    PubMed Central

    Michaelson, S M

    1982-01-01

    ABSTRACT The rapid development of and the increase in the number and variety of devices that emit microwave/radiofrequency (MW/RF) energies has resulted in a growing interest regarding the potential effects on health of these energies. The frequency ranges considered in this review are: 300 kHz to 300 MHz (radiofrequency) and 300 MHz to 300 GHz (microwaves). Investigations have shown that exposure to certain power densities for several minutes or hours can result in pathophysiological manifestations in laboratory animals. Such effects may or may not be characterised by a measurable rise in temperature, which is a function of thermal regulatory processes and active adaptation by the animal. The end result is either a reversible or irreversible change, depending on the irradiation conditions and the physiological state of the animal. At lower power densities, evidence of pathological changes or physiological alteration is non-existent or equivocal. Much discussion, nevertheless, has taken place on the relative importance of thermal or non-thermal effects of radiofrequency and microwave radiation. Several retrospective studies have been done on human populations exposed or believed to have been exposed to MW/RF energies. Those performed in the US have not shown any relationship of altered morbidity or mortality to MW/RF exposure. Reactions referrable to the central nervous system and cardiovascular effects from exposure of man to microwave energy have been reported mostly in Eastern European publications. Individuals suffering from various ailments or psychological factors may exhibit the same dysfunctions of the central nervous and cardiovascular systems as those reported to result from exposure to MW/RF; thus it is extremely difficult, if not impossible, to rule out other factors in attempting to relate MW/RF exposure to clinical conditions. There is a need to set limits on the amount of exposure to MW/RF energies that individuals can accept with safety. Operative

  13. Creating Feshbach resonances for ultracold molecule formation with radio-frequency fields

    NASA Astrophysics Data System (ADS)

    Owens, Daniel J.; Xie, Ting; Hutson, Jeremy M.

    2016-08-01

    We show that radio-frequency (rf) radiation may be used to create Feshbach resonances in ultracold gases of alkali-metal atoms at desired magnetic fields that are convenient for atomic cooling and degeneracy. For the case of 39K+133Cs , where there are no rf-free resonances in regions where Cs may be cooled to degeneracy, we show that a resonance may be created near 21 G with 69.2 MHz rf radiation. This resonance is almost lossless with circularly polarized rf, and the molecules created are long-lived even with plane-polarized rf.

  14. Radiofrequency ablation of abdominal wall endometrioma.

    PubMed

    Carrafiello, Gianpaolo; Fontana, Federico; Pellegrino, Carlo; Mangini, Monica; Cabrini, Luca; Mariani, Davide; Piacentino, Filippo; Cuffari, Salvatore; Laganà, Domenico; Fugazzola, Carlo

    2009-11-01

    Extraperitoneal endometriosis is the presence of ectopic, functional endometrium outside the peritoneal cavity, and its occurrence is exceedingly rare. Diagnostic imaging--including ultrasound, duplex ultrasonography, and magnetic resonance imaging--in the preoperative assessment of patients with suspected abdominal wall endometriosis (AWE) is helpful for detection and accurate determination of the extent of disease. The treatment of choice for AWE is surgical excision. In addition, medical therapies can be used. We present one case of AWE treated with percutaneous radiofrequency ablation under ultrasound guidance. There were no major complications, and the patient's symptoms improved. In selected patients, radiofrequency ablation can be used safely for the treatment of AWE; however, further studies are needed to confirm this hypothesis. PMID:19184197

  15. Radiofrequency-oxidation treatment of sewage sludge.

    PubMed

    Srinivasan, Asha; Young, Chris; Liao, Ping H; Lo, Kwang V

    2015-12-01

    A novel thermal-chemical treatment technology using radiofrequency heating and oxidants (hydrogen peroxide, ozone and a combination of both) was used for the treatment of sewage sludge. This was to evaluate the process effectiveness on cell disintegration and nutrient release of sludge, physical property changes such as particle size distribution, dewaterability and settleability, and their inter-relationships. The effectiveness of treatment processes was in the following order, from the most to least: thermal-oxidation process, oxidation process and thermal process. The thermal-oxidation process greatly increased cell disintegration and nutrient release, improved settleability, and decreased particle sizes. The treatment scheme involving ozone addition followed by hydrogen peroxide and radiofrequency heating yielded the highest soluble chemical oxygen demand, volatile fatty acids, ammonia and metals, while proffering the shortest capillary suction time and excellent settling properties. PMID:26233925

  16. Bilateral vision loss associated with radiofrequency exposure

    PubMed Central

    Liu, Dianna; Cruz, Franz Marie; Subramanian, Prem S

    2012-01-01

    A 57-year-old otherwise healthy woman presented with painless binocular vision loss 1 week after direct application of radiofrequency energy to her orbits. She had no light perception bilaterally. Pupils were dilated and not reactive to light. Fundoscopic exam initially showed optic disc swelling in the right eye and a normal-appearing disc in the left eye. Magnetic resonance imaging of the brain and orbits showed gadolinium enhancement of both intraorbital optic nerves. She underwent a course of high-dose steroid treatment without recovery of vision. Optic discs were pale 11 weeks after injury. With exclusion of other possible causes, this represents a unique case of irreversible binocular optic nerve damage and blindness secondary to radiofrequency exposure. PMID:23271888

  17. Fraxelated radiofrequency device for acne scars

    NASA Astrophysics Data System (ADS)

    Rao, Babar K.; Khokher, Sairah

    2012-09-01

    Acne scars can be improved with various treatments such as topical creams, chemical peels, dermal fillers, microdermabrasion, laser, and radiofrequency devices. Some of these treatments especially lasers and deep chemical peels can have significant side effects such as post inflammatory hyperpigmentation in darker skin types. Fraxelated RF Laser devices have been reported to have lower incidence of side effects in all skin phototypes. Nine patients between ages 18 and 35 of various skin phototypes were selected from a private practice and treated with a RF fraxelated device (E-matrix) for acne scars. Outcomes were measured by physician observation, subjective feedback received by patients, and comparison of before and after photographs. In this small group of patients with various skin phototypes, fraxelated radiofrequency device improved acne scars with minimal side effects and downtime.

  18. Radiofrequency and microwave interactions between biomolecular systems.

    PubMed

    Kučera, Ondřej; Cifra, Michal

    2016-01-01

    The knowledge of mechanisms underlying interactions between biological systems, be they biomacromolecules or living cells, is crucial for understanding physiology, as well as for possible prevention, diagnostics and therapy of pathological states. Apart from known chemical and direct contact electrical signaling pathways, electromagnetic phenomena were proposed by some authors to mediate non-chemical interactions on both intracellular and intercellular levels. Here, we discuss perspectives in the research of nanoscale electromagnetic interactions between biosystems on radiofrequency and microwave wavelengths. Based on our analysis, the main perspectives are in (i) the micro and nanoscale characterization of both passive and active radiofrequency properties of biomacromolecules and cells, (ii) experimental determination of viscous damping of biomacromolecule structural vibrations and (iii) detailed analysis of energetic circumstances of electromagnetic interactions between oscillating polar biomacromolecules. Current cutting-edge nanotechnology and computational techniques start to enable such studies so we can expect new interesting insights into electromagnetic aspects of molecular biophysics of cell signaling. PMID:26174548

  19. Superconducting surface impedance under radiofrequency field

    DOE PAGESBeta

    Xiao, Binping P.; Reece, Charles E.; Kelley, Michael J.

    2013-04-26

    Based on BCS theory with moving Cooper pairs, the electron states distribution at 0K and the probability of electron occupation with finite temperature have been derived and applied to anomalous skin effect theory to obtain the surface impedance of a superconductor under radiofrequency (RF) field. We present the numerical results for Nb and compare these with representative RF field-dependent effective surface resistance measurements from a 1.5 GHz resonant structure.

  20. Radiofrequency Wire Recanalization of Chronically Thrombosed TIPS.

    PubMed

    Majdalany, Bill S; Elliott, Eric D; Michaels, Anthony J; Hanje, A James; Saad, Wael E A

    2016-07-01

    Radiofrequency (RF) guide wires have been applied to cardiac interventions, recanalization of central venous thromboses, and to cross biliary occlusions. Herein, the use of a RF wire technique to revise chronically occluded transjugular intrahepatic portosystemic shunts (TIPS) is described. In both cases, conventional TIPS revision techniques failed to revise the chronically thrombosed TIPS. RF wire recanalization was successfully performed through each of the chronically thrombosed TIPS, demonstrating initial safety and feasibility in this application. PMID:26902703

  1. Ultrasound-guided Pulsed Radiofrequency of the Third Occipital Nerve

    PubMed Central

    Kim, Eung Don; Kim, Young Hoon; Park, Chong Min; Kwak, Jung Ah

    2013-01-01

    A C2-3 zygapophygeal joint is a major source of cervicogenic headache. Radiofrequency (RF) neurotomy is preformed widely for zygapophygeal joint pain. Conventional RF denervation technique is generally performed under fluoroscopic control. Recently, ultrasound-guided radiofrequency on zygapophygeal joint has emerged as an alternative method. We report our experiences of two successful ultrasound-guided pulsed radiofrequencies on 39-year-old and 42-year-old males, who complained occipital headache and posterior neck pain. PMID:23614084

  2. Radiofrequency Microtenotomy for Elbow Epicondylitis: Midterm Results.

    PubMed

    Tasto, James P; Richmond, John M; Cummings, Jeffrey R; Hardesty, Renee; Amiel, David

    2016-01-01

    We conducted a prospective, nonrandomized, single-center clinical study to evaluate the safety and midterm effectiveness of microtenotomy using a radiofrequency probe to treat chronic tendinosis of the elbow. All patients had failed conservative treatment for 6 months. The radiofrequency-based microtenotomy was performed using the Topaz Microdebrider (ArthroCare). Patients were followed annually for up to 9 years postoperatively. Pain status was documented using a visual analog scale self-reported measure. Eighty consecutive patients with tendinosis of the elbow were enrolled; 69 patients were treated for lateral epicondylitis and 11 for medial epicondylitis. The duration of follow-up ranged from 6 months to 9 years (mean, 2.5 years). Ninety-one percent of the patients reported a successful outcome. Within the lateral epicondylitis group, the preoperative visual analog scale improved from 6.9 to 1.3 postoperatively and demonstrated an 81% improvement (P ≤ .01). For the medial epicondylitis patients, the preoperative visual analog scale improved from 6.1 to 1.3 after surgery, a 79% improvement (P ≤ .01). No complications were reported. Radiofrequency-based microtenotomy is a safe and effective procedure for elbow epicondylitis. The results are durable with successful outcomes observed at 9 years after surgery. PMID:26761915

  3. Biological indicators in response to radiofrequency/microwave exposure.

    PubMed

    Marjanović, Ana Marija; Pavičić, Ivan; Trošić, Ivančica

    2012-09-01

    Over the years, due to rapid technological progress, radiation from man-made sources exceeded that of natural origin. There is a general concern regarding a growing number of appliances that use radiofrequency/ microwave (RF/MW) radiation with particular emphasis on mobile communication systems. Since nonthermal biological effects and mechanisms of RF/MW radiation are still uncertain, laboratory studies on animal models, tissues, cells, and cell free system are of extraordinary importance in bioelectromagnetic research. We believe that such investigations play a supporting role in public risk assessment. Cellular systems with the potential for a clear response to RF/MW exposures should be used in those studies. It is known that organism is a complex electrochemical system where processes of oxidation and reduction regularly occur. One of the plausible mechanisms is connected with generation of reactive oxygen species (ROS). Depending on concentration, ROS can have both beneficial and deleterious effects. Positive effects are connected with cell signalling, defence against infectious agents, and proliferative cell ability. On the other hand, excessive production, which overloads antioxidant defence mechanism, leads to cellular damage with serious potential for disease development. ROS concentration increase within the cell caused by RF/MW radiation seems to be a biologically relevant hypothesis to give clear insight into the RF/MW action at non-thermal level of radiation. In order to better understand the exact mechanism of action and its consequences, further research is needed in the field. We would like to present current knowledge on possible biological mechanisms of RF/MW actions. PMID:23152390

  4. Diverse Radiofrequency Sensitivity and Radiofrequency Effects of Mobile or Cordless Phone near Fields Exposure in Drosophila melanogaster

    PubMed Central

    Geronikolou, Styliani; Zimeras, Stelios; Davos, Constantinos H.; Michalopoulos, Ioannis; Tsitomeneas, Stephanos

    2014-01-01

    Introduction The impact of electromagnetic fields on health is of increasing scientific interest. The aim of this study was to examine how the Drosophila melanogaster animal model is affected when exposed to portable or mobile phone fields. Methods/Results Two experiments have been designed and performed in the same laboratory conditions. Insect cultures were exposed to the near field of a 2G mobile phone (the GSM 2G networks support and complement in parallel the 3G wide band or in other words the transmission of information via voice signals is served by the 2G technology in both mobile phones generations) and a 1880 MHz cordless phone both digitally modulated by human voice. Comparison with advanced statistics of the egg laying of the second generation exposed and non-exposed cultures showed limited statistical significance for the cordless phone exposed culture and statistical significance for the 900 MHz exposed insects. We calculated by physics, simulated and illustrated in three dimensional figures the calculated near fields of radiation inside the experimenting vials and their difference. Comparison of the power of the two fields showed that the difference between them becomes null when the experimental cylinder radius and the height of the antenna increase. Conclusions/Significance Our results suggest a possible radiofrequency sensitivity difference in insects which may be due to the distance from the antenna or to unexplored intimate factors. Comparing the near fields of the two frequencies bands, we see similar not identical geometry in length and height from the antenna and that lower frequencies tend to drive to increased radiofrequency effects. PMID:25402465

  5. Mechanisms of biological effects of radiofrequency electromagnetic fields: an overview

    SciTech Connect

    Erwin, D.N.

    1988-11-01

    Manmade sources of electromagnetic (EM) fields, and therefore human exposures to them, continue to increase. Public concerns stem from the effects reported in the literature, the visibility of the sources, and somewhat from confusion between EM fields and ionizing radiation. Protecting humans from the real hazards and allaying groundless fears requires a self-consistent body of scientific data concerning effects of the fields, levels of exposures which cause those effects, and which effects are deleterious (or beneficial or neutral). With that knowledge, appropriate guidelines for safety can be devised, while preserving the beneficial uses of radiofrequency radiation (RFR) energy for military or civilian purposes. The task is monumental because of the large and growing number of biological endpoints and the infinite array of RFR exposure conditions under which those endpoints might be examined. The only way to reach this goal is to understand the mechanisms by which EM fields interact with tissues. As in other fields of science, a mechanistic understanding of RFR effects will enable scientists to generalize from a selected few experiments to derive the laws of RFR bioeffects. This article gives an overview of present knowledge of those mechanisms and the part that the USAF School of Aerospace Medicine has played in expanding that knowledge. 91 references.

  6. Association of Exposure to Radio-Frequency Electromagnetic Field Radiation (RF-EMFR) Generated by Mobile Phone Base Stations with Glycated Hemoglobin (HbA1c) and Risk of Type 2 Diabetes Mellitus

    PubMed Central

    Meo, Sultan Ayoub; Alsubaie, Yazeed; Almubarak, Zaid; Almutawa, Hisham; AlQasem, Yazeed; Muhammed Hasanato, Rana

    2015-01-01

    Installation of mobile phone base stations in residential areas has initiated public debate about possible adverse effects on human health. This study aimed to determine the association of exposure to radio frequency electromagnetic field radiation (RF-EMFR) generated by mobile phone base stations with glycated hemoglobin (HbA1c) and occurrence of type 2 diabetes mellitus. For this study, two different elementary schools (school-1 and school-2) were selected. We recruited 159 students in total; 96 male students from school-1, with age range 12–16 years, and 63 male students with age range 12–17 years from school-2. Mobile phone base stations with towers existed about 200 m away from the school buildings. RF-EMFR was measured inside both schools. In school-1, RF-EMFR was 9.601 nW/cm2 at frequency of 925 MHz, and students had been exposed to RF-EMFR for a duration of 6 h daily, five days in a week. In school-2, RF-EMFR was 1.909 nW/cm2 at frequency of 925 MHz and students had been exposed for 6 h daily, five days in a week. 5–6 mL blood was collected from all the students and HbA1c was measured by using a Dimension Xpand Plus Integrated Chemistry System, Siemens. The mean HbA1c for the students who were exposed to high RF-EMFR was significantly higher (5.44 ± 0.22) than the mean HbA1c for the students who were exposed to low RF-EMFR (5.32 ± 0.34) (p = 0.007). Moreover, students who were exposed to high RF-EMFR generated by MPBS had a significantly higher risk of type 2 diabetes mellitus (p = 0.016) relative to their counterparts who were exposed to low RF-EMFR. It is concluded that exposure to high RF-EMFR generated by MPBS is associated with elevated levels of HbA1c and risk of type 2 diabetes mellitus. PMID:26580639

  7. Association of Exposure to Radio-Frequency Electromagnetic Field Radiation (RF-EMFR) Generated by Mobile Phone Base Stations with Glycated Hemoglobin (HbA1c) and Risk of Type 2 Diabetes Mellitus.

    PubMed

    Meo, Sultan Ayoub; Alsubaie, Yazeed; Almubarak, Zaid; Almutawa, Hisham; AlQasem, Yazeed; Hasanato, Rana Muhammed

    2015-11-01

    Installation of mobile phone base stations in residential areas has initiated public debate about possible adverse effects on human health. This study aimed to determine the association of exposure to radio frequency electromagnetic field radiation (RF-EMFR) generated by mobile phone base stations with glycated hemoglobin (HbA1c) and occurrence of type 2 diabetes mellitus. For this study, two different elementary schools (school-1 and school-2) were selected. We recruited 159 students in total; 96 male students from school-1, with age range 12-16 years, and 63 male students with age range 12-17 years from school-2. Mobile phone base stations with towers existed about 200 m away from the school buildings. RF-EMFR was measured inside both schools. In school-1, RF-EMFR was 9.601 nW/cm² at frequency of 925 MHz, and students had been exposed to RF-EMFR for a duration of 6 h daily, five days in a week. In school-2, RF-EMFR was 1.909 nW/cm² at frequency of 925 MHz and students had been exposed for 6 h daily, five days in a week. 5-6 mL blood was collected from all the students and HbA1c was measured by using a Dimension Xpand Plus Integrated Chemistry System, Siemens. The mean HbA1c for the students who were exposed to high RF-EMFR was significantly higher (5.44 ± 0.22) than the mean HbA1c for the students who were exposed to low RF-EMFR (5.32 ± 0.34) (p = 0.007). Moreover, students who were exposed to high RF-EMFR generated by MPBS had a significantly higher risk of type 2 diabetes mellitus (p = 0.016) relative to their counterparts who were exposed to low RF-EMFR. It is concluded that exposure to high RF-EMFR generated by MPBS is associated with elevated levels of HbA1c and risk of type 2 diabetes mellitus. PMID:26580639

  8. Radiation

    NASA Video Gallery

    Outside the protective cocoon of Earth's atmosphere, the universe is full of harmful radiation. Astronauts who live and work in space are exposed not only to ultraviolet rays but also to space radi...

  9. 21 CFR 886.4100 - Radiofrequency electrosurgical cautery apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiofrequency electrosurgical cautery apparatus. 886.4100 Section 886.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4100 Radiofrequency electrosurgical cautery apparatus....

  10. 21 CFR 882.4725 - Radiofrequency lesion probe.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiofrequency lesion probe. 882.4725 Section 882.4725 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4725 Radiofrequency lesion probe. (a) Identification. A...

  11. 21 CFR 886.4100 - Radiofrequency electrosurgical cautery apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiofrequency electrosurgical cautery apparatus. 886.4100 Section 886.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4100 Radiofrequency electrosurgical cautery apparatus....

  12. 21 CFR 886.4100 - Radiofrequency electrosurgical cautery apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiofrequency electrosurgical cautery apparatus. 886.4100 Section 886.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4100 Radiofrequency electrosurgical cautery apparatus....

  13. 21 CFR 882.4400 - Radiofrequency lesion generator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiofrequency lesion generator. 882.4400 Section 882.4400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lesion generator. (a) Identification. A radiofrequency lesion generator is a device used to...

  14. 21 CFR 882.4400 - Radiofrequency lesion generator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiofrequency lesion generator. 882.4400 Section 882.4400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lesion generator. (a) Identification. A radiofrequency lesion generator is a device used to...

  15. 21 CFR 882.4400 - Radiofrequency lesion generator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiofrequency lesion generator. 882.4400 Section 882.4400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lesion generator. (a) Identification. A radiofrequency lesion generator is a device used to...

  16. 21 CFR 882.4400 - Radiofrequency lesion generator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiofrequency lesion generator. 882.4400 Section 882.4400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lesion generator. (a) Identification. A radiofrequency lesion generator is a device used to...

  17. 21 CFR 882.4400 - Radiofrequency lesion generator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiofrequency lesion generator. 882.4400 Section 882.4400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lesion generator. (a) Identification. A radiofrequency lesion generator is a device used to...

  18. 21 CFR 886.4100 - Radiofrequency electrosurgical cautery apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiofrequency electrosurgical cautery apparatus. 886.4100 Section 886.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... electrosurgical cautery apparatus. (a) Identification. A radiofrequency electrosurgical cautery apparatus is an...

  19. Active stabilization of ion trap radiofrequency potentials

    NASA Astrophysics Data System (ADS)

    Johnson, K. G.; Wong-Campos, J. D.; Restelli, A.; Landsman, K. A.; Neyenhuis, B.; Mizrahi, J.; Monroe, C.

    2016-05-01

    We actively stabilize the harmonic oscillation frequency of a laser-cooled atomic ion confined in a radiofrequency (rf) Paul trap by sampling and rectifying the high voltage rf applied to the trap electrodes. We are able to stabilize the 1 MHz atomic oscillation frequency to be better than 10 Hz or 10 ppm. This represents a suppression of ambient noise on the rf circuit by 34 dB. This technique could impact the sensitivity of ion trap mass spectrometry and the fidelity of quantum operations in ion trap quantum information applications.

  20. Radiofrequency Ablation Complicated by Skin Burn

    PubMed Central

    Huffman, S.D.; Huffman, N.P.; Lewandowski, Robert J.; Brown, Daniel B.

    2011-01-01

    Radiofrequency (RF) ablation has been increasingly utilized as a minimally invasive treatment for primary and metastatic liver tumors, as well as tumors in the kidneys, bones, and adrenal glands. The development of high-current RF ablation has subsequently led to an increased risk of thermal skin injuries at the grounding pad site. The incidence of skin burns in recent studies ranges from 0.1–3.2% for severe skin burns (second-/third-degree), and from 5–33% for first-degree burns.1–3 PMID:22654258

  1. Radiofrequency in Cosmetic Dermatology: An Update.

    PubMed

    Dunbar, Scott W; Goldberg, David J

    2015-11-01

    Treatment options for cosmetic improvement of the skin and body continue to grow more numerous with each passing year. The decline in utilization of invasive surgical treatments for aging and body contour correlates with the recent rise in laser and light devices. These light based technologies transmit either a single or broad wavelength of amplified light to the skin, resulting in volumetric tissue heating. Depending on the chromophore targeted and wavelength applied, varied applications exist to treat numerous cosmetic concerns. Radiofrequency (RF) devices have become more popular recently as science has advanced and brought new, safer, and better therapies. PMID:26580871

  2. Radiofrequency Ablation to Prevent Sudden Cardiac Death

    PubMed Central

    Atoui, Moustapha; Gunda, Sampath; Lakkireddy, Dhanunjaya; Mahapatra, Srijoy

    2015-01-01

    Radiofrequency ablation may prevent or treat atrial and ventricular arrhythmias. Since some of these arrhythmias are associated with sudden cardiac death, it has been hypothesized that ablation may prevent sudden death in certain cases. We performed a literature search to better understand under which circumstances ablation may prevent sudden death and found little randomized data demonstrating the long-term effects of ablation. Current literature shows that ablation clearly prevents symptoms of arrhythmia and may reduce the incidence of sudden cardiac death in select patients, although data does not indicate improved mortality. Ongoing clinical trials are needed to better define the role of ablation in preventing sudden cardiac death. PMID:26306130

  3. Radiofrequency ablation for benign thyroid nodules.

    PubMed

    Bernardi, S; Stacul, F; Zecchin, M; Dobrinja, C; Zanconati, F; Fabris, B

    2016-09-01

    Benign thyroid nodules are an extremely common occurrence. Radiofrequency ablation (RFA) is gaining ground as an effective technique for their treatment, in case they become symptomatic. Here we review what are the current indications to RFA, its outcomes in terms of efficacy, tolerability, and cost, and also how it compares to the other conventional and experimental treatment modalities for benign thyroid nodules. Moreover, we will also address the issue of treating with this technique patients with cardiac pacemakers (PM) or implantable cardioverter-defibrillators (ICD), as it is a rather frequent occurrence that has never been addressed in detail in the literature. PMID:27098804

  4. Radio Frequency Radiation (RFR) measurements in operational settings

    NASA Astrophysics Data System (ADS)

    Graham, R. B.

    1984-12-01

    This report is an overview and summary of how the USAF carries out the field measurement aspects of the radiofrequency radiation protection program and offers some broad guidelines as to how other agencies might accomplish the same mission.

  5. Radio-frequency scanning tunnelling microscopy.

    PubMed

    Kemiktarak, U; Ndukum, T; Schwab, K C; Ekinci, K L

    2007-11-01

    The scanning tunnelling microscope (STM) relies on localized electron tunnelling between a sharp probe tip and a conducting sample to attain atomic-scale spatial resolution. In the 25-year period since its invention, the STM has helped uncover a wealth of phenomena in diverse physical systems--ranging from semiconductors to superconductors to atomic and molecular nanosystems. A severe limitation in scanning tunnelling microscopy is the low temporal resolution, originating from the diminished high-frequency response of the tunnel current readout circuitry. Here we overcome this limitation by measuring the reflection from a resonant inductor-capacitor circuit in which the tunnel junction is embedded, and demonstrate electronic bandwidths as high as 10 MHz. This approximately 100-fold bandwidth improvement on the state of the art translates into fast surface topography as well as delicate measurements in mesoscopic electronics and mechanics. Broadband noise measurements across the tunnel junction using this radio-frequency STM have allowed us to perform thermometry at the nanometre scale. Furthermore, we have detected high-frequency mechanical motion with a sensitivity approaching approximately 15 fm Hz(-1/2). This sensitivity is on par with the highest available from nanoscale optical and electrical displacement detection techniques, and the radio-frequency STM is expected to be capable of quantum-limited position measurements. PMID:17972882

  6. Neurohumoral indicators of efficacy radiofrequency cardiac denervation

    NASA Astrophysics Data System (ADS)

    Evtushenko, A. V.; Evtushenko, V. V.; Saushkina, Yu. V.; Lishmanov, Yu. B.; Pokushalov, E. A.; Sergeevichev, D. S.; Gusakova, A. M.; Suslova, T. E.; Dymbrylova, O. N.; Bykov, A. N.; Syryamkin, V. I.; Kistenev, Yu. V.; Anfinogenova, Ya. D.; Smyshlyaev, K. A.; Lotkov, A. I.; Kurlov, I. O.

    2015-11-01

    In this study, we compared pre- and postoperative parameters of the cardiac sympathetic innervation. The aim of the study was to examine the approaches to evaluating the quality of radiofrequency (RF)-induced cardiac denervation by using non-invasive and laboratory methods. The study included 32 people with long-lasting persistent atrial fibrillation (AF). The patients were divided into 2 groups according to the objectives of the study: group 1 (main) - 21 patients with mitral valve diseases, which simultaneously with radiofrequency ablation (RFA) AF carried out on the effects of the paraganglionic nervous plexuses by C. Pappone (2004) and N. Doll (2008) schemes. The second group (control) contained 11 patients with heart diseases in sinus rhythm (the RF denervation not been performed). All patients, who underwent surgical treatment, were received examination of cardiac sympathetic tone by using 123I-MIBG. All of them made blood analysis from ascending aorta and coronary sinus to determine the level of norepinephrine and its metabolites before and after cardiac denervation. Data of radionuclide examination are correlating with laboratory data.

  7. Neurohumoral indicators of efficacy radiofrequency cardiac denervation

    SciTech Connect

    Evtushenko, A. V. Evtushenko, V. V.; Saushkina, Yu. V.; Gusakova, A. M.; Suslova, T. E.; Dymbrylova, O. N.; Smyshlyaev, K. A.; Kurlov, I. O.; Lishmanov, Yu. B.; Anfinogenova, Ya. D.; Sergeevichev, D. S.; Bykov, A. N.; Syryamkin, V. I.; Kistenev, Yu. V.; Lotkov, A. I.; Pokushalov, E. A.

    2015-11-17

    In this study, we compared pre- and postoperative parameters of the cardiac sympathetic innervation. The aim of the study was to examine the approaches to evaluating the quality of radiofrequency (RF)-induced cardiac denervation by using non-invasive and laboratory methods. The study included 32 people with long-lasting persistent atrial fibrillation (AF). The patients were divided into 2 groups according to the objectives of the study: group 1 (main) - 21 patients with mitral valve diseases, which simultaneously with radiofrequency ablation (RFA) AF carried out on the effects of the paraganglionic nervous plexuses by C. Pappone (2004) and N. Doll (2008) schemes. The second group (control) contained 11 patients with heart diseases in sinus rhythm (the RF denervation not been performed). All patients, who underwent surgical treatment, were received examination of cardiac sympathetic tone by using {sup 123}I-MIBG. All of them made blood analysis from ascending aorta and coronary sinus to determine the level of norepinephrine and its metabolites before and after cardiac denervation. Data of radionuclide examination are correlating with laboratory data.

  8. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    NASA Astrophysics Data System (ADS)

    Li, Guo; Li, He-Ping; Wang, Li-Yan; Wang, Sen; Zhao, Hong-Xin; Sun, Wen-Ting; Xing, Xin-Hui; Bao, Cheng-Yu

    2008-06-01

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  9. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    SciTech Connect

    Li Guo; Li Heping; Wang Sen; Sun Wenting; Bao Chengyu; Wang Liyan; Zhao Hongxin; Xing Xinhui

    2008-06-02

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  10. Transmission of Mössbauer rays through ferromagnets in radio-frequency magnetic field

    NASA Astrophysics Data System (ADS)

    Dzyublik, A. Ya.; Sadykov, E. K.; Petrov, G. I.; Arinin, V. V.; Vagizov, F. G.; Spivak, V. Yu.

    2013-08-01

    The transmission of Mössbauer radiation through a thick ferromagnetic crystal, exposed to a radio-frequency (rf) magnetic field, is studied. The quantum-mechanical dynamical scattering theory is developed, taking into account the periodical reversals of the magnetic field at the nuclei. The Mössbauer forward scattering (FS) spectra of the weak ferromagnet FeBO3 placed into rf field are measured. It is found that the coherent gamma wave in the crystal absorbs or emits only couples of the rf photons. As a result, the FS spectra consist of equidistant lines spaced by twice the frequency of the rf field in contrast to the absorption spectra.

  11. 47 CFR 1.1310 - Radiofrequency radiation exposure limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... American National Standards Institute (ANSI) for localized SAR in § 4.2 of “IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz,” ANSI/IEEE... density are also generally based on criteria recommended by the ANSI in § 4.1 of “IEEE Standard for...

  12. 47 CFR 1.1310 - Radiofrequency radiation exposure limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... recommended by the American National Standards Institute (ANSI) in Section 4.1 of “IEEE Standard for Safety.../IEEE C95.1-1992, Copyright 1992 by the Institute of Electrical and Electronics Engineers, Inc.,...

  13. 47 CFR 1.1310 - Radiofrequency radiation exposure limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... American National Standards Institute (ANSI) for localized SAR in § 4.2 of “IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz,” ANSI/IEEE... density are also generally based on criteria recommended by the ANSI in § 4.1 of “IEEE Standard for...

  14. 47 CFR 1.1310 - Radiofrequency radiation exposure limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... frequency range from 100 MHz to 1500 MHz, exposure limits for field strength and power density are also...) Frequency range(MHz) Electric field strength(V/m) Magnetic field strength(A/m) Power density(mW/cm2... equivalent power density Note 1 to Table 1: Occupational/controlled limits apply in situations in...

  15. EEDF evolution in pulsed radio-frequency plasmas

    NASA Astrophysics Data System (ADS)

    El Otell, Ziad; Bowden, Mark; Braithwaite, Nicholas

    2012-10-01

    We investigate the evolution of the electron energy distribution function (EEDF) in pulsed radio-frequency plasmas using a simple form of trace rare gas optical emission spectroscopy. For steady-state discharges, methods exist to determine electron temperatures and EEDFs using emission measurements and collisional radiative models. However, these methods rely on the EEDF being stable and are difficult to use in the rapidly changing transients in a pulsed discharge. We assess a simpler technique in which we compare the time-dependence of emission from different plasma species in order to infer information about the evolution of the EEDF. The study was carried out in a capacitively coupled rf discharge generated in a Gaseous Electronic Conference (GEC) reference reactor. The gas mixture consisted of mainly argon with small amounts of xenon and krypton. Emission was measured on specific lines from argon, krypton and xenon, chosen due to their emission being predominantly due to direct excitation from the ground state. For the case of square pulse excitation, the EEDF in the early part of each pulse was dominated by beam-like electrons with high energy. This beam-like EEDF phase was absent when a pulse with a less steep rise time was used.

  16. In vitro and in vivo genotoxicity of radiofrequency fields.

    PubMed

    Verschaeve, L; Juutilainen, J; Lagroye, I; Miyakoshi, J; Saunders, R; de Seze, R; Tenforde, T; van Rongen, E; Veyret, B; Xu, Z

    2010-12-01

    There has been growing concern about the possibility of adverse health effects resulting from exposure to radiofrequency radiations (RFR), such as those emitted by wireless communication devices. Since the introduction of mobile phones many studies have been conducted regarding alleged health effects but there is still some uncertainty and no definitive conclusions have been reached so far. Although thermal effects are well understood they are not of great concern as they are unlikely to result from the typical low-level RFR exposures. Concern rests essentially with the possibility that RFR-exposure may induce non-thermal and/or long-term health effects such as an increased cancer risk. Consequently, possible genetic effects have often been studied but with mixed results. In this paper we review the data on alleged RFR-induced genetic effects from in vitro and in vivo investigations as well as from human cytogenetic biomonitoring surveys. Attention is also paid to combined exposures of RFR with chemical or physical agents. Again, however, no entirely consistent picture emerges. Many of the positive studies may well be due to thermal exposures, but a few studies suggest that biological effects can be seen at low levels of exposure. Overall, however, the evidence for low-level genotoxic effects is very weak. PMID:20955816

  17. Compact Superconducting Radio-frequency Accelerators and Innovative RF Systems

    SciTech Connect

    Kephart, Robert; Chattopadhyay, Swaapan; Milton, Stephen

    2015-04-10

    We will present several new technical and design breakthroughs that enable the creation of a new class of compact linear electron accelerators for industrial purposes. Use of Superconducting Radio-Frequency (SRF) cavities allow accelerators less than 1.5 M in length to create electron beams beyond 10 MeV and with average beam powers measured in 10’s of KW. These machines can have the capability to vary the output energy dynamically to produce brehmstrahlung x-rays of varying spectral coverage for applications such as rapid scanning of moving cargo for security purposes. Such compact accelerators will also be cost effective for many existing and new industrial applications. Examples include radiation crosslinking of plastics and rubbers, creation of pure materials with surface properties radically altered from the bulk, modification of bulk or surface optical properties of materials, sterilization of medical instruments animal solid or liquid waste, and destruction of organic compounds in industrial waste water effluents. Small enough to be located on a mobile platform, such accelerators will enable new remediation methods for chemical and biological spills and/or in-situ crosslinking of materials. We will describe one current design under development at Fermilab including plans for prototype and value-engineering to reduce costs. We will also describe development of new nano-structured field-emitter arrays as sources of electrons, new methods for fabricating and cooling superconducting RF cavities, and a new novel RF power source based on magnetrons with full phase and amplitude control.

  18. Thermal compression and molding of atherosclerotic vascular tissue with use of radiofrequency energy: implications for radiofrequency balloon angioplasty

    SciTech Connect

    Lee, B.I.; Becker, G.J.; Waller, B.F.; Barry, K.J.; Connolly, R.J.; Kaplan, J.; Shapiro, A.R.; Nardella, P.C.

    1989-04-01

    The combined delivery of pressure and thermal energy may effectively remodel intraluminal atherosclerotic plaque and fuse intimal tears. To test these hypotheses with use of a non-laser thermal energy source, radiofrequency energy was delivered to postmortem human atherosclerotic vessels from a metal hot-tip catheter, block-mounted bipolar electrodes and from a prototype radiofrequency balloon catheter. Sixty-two radiofrequency doses delivered from a metal electrode tip produced dose-dependent ablation of atherosclerotic plaque, ranging from clean and shallow craters with histologic evidence of thermal compression at doses less than 40 J to tissue charring and vaporization at higher (greater than 80 J) doses. Lesion dimensions ranged between 3.14 and 3.79 mm in diameter and 0.20 and 0.47 mm in depth. Tissue perforation was not observed. To test the potential for radiofrequency fusion of intimal tears, 5 atm of pressure and 200 J radiofrequency energy were delivered from block-mounted bipolar electrodes to 48 segments of human atherosclerotic aorta, which had been manually separated into intima-media and media-adventitial layers. Significantly stronger tissue fusion resulted (28.5 +/- 3.3 g) with radiofrequency compared with that with pressure alone (4.8 +/- 0.26 g; p less than 0.0001). A prototype radiofrequency balloon catheter was used to deliver 3 atm of balloon pressure with or without 200 J radiofrequency energy to 20 postmortem human atherosclerotic arterial segments. In 10 of 10 radiofrequency-treated vessels, thermal molding of both normal and atherosclerotic vessel wall segments resulted with increased luminal diameter and histologic evidence of medial myocyte damage.

  19. Electromagnetic limits to radiofrequency (RF) neuronal telemetry

    NASA Astrophysics Data System (ADS)

    Diaz, R. E.; Sebastian, T.

    2013-12-01

    The viability of a radiofrequency (RF) telemetry channel for reporting individual neuron activity wirelessly from an embedded antenna to an external receiver is determined. Comparing the power at the transmitting antenna required for the desired Channel Capacity, to the maximum power that this antenna can dissipate in the body without altering or damaging surrounding tissue reveals the severe penalty incurred by miniaturization of the antenna. Using both Specific Absorption Rate (SAR) and thermal damage limits as constraints, and 300 Kbps as the required capacity for telemetry streams 100 ms in duration, the model shows that conventional antennas smaller than 0.1 mm could not support human neuronal telemetry to a remote receiver (1 m away.) Reducing the antenna to 10 microns in size to enable the monitoring of single human neuron signals to a receiver at the surface of the head would require operating with a channel capacity of only 0.3 bps.

  20. Palliative Radiofrequency Ablation for Recurrent Prostate Cancer

    SciTech Connect

    Jindal, Gaurav; Friedman, Marc; Locklin, Julia Wood, Bradford J.

    2006-06-15

    Percutaneous radiofrequency ablation (RFA) is a minimally invasive local therapy for cancer. Its efficacy is now becoming well documented in many different organs, including liver, kidney, and lung. The goal of RFA is typically complete eradication of a tumor in lieu of an invasive surgical procedure. However, RFA can also play an important role in the palliative care of cancer patients. Tumors which are surgically unresectable and incompatible for complete ablation present the opportunity for RFA to be used in a new paradigm. Cancer pain runs the gamut from minor discomfort relieved with mild pain medication to unrelenting suffering for the patient, poorly controlled by conventional means. RFA is a tool which can potentially palliate intractable cancer pain. We present here a case in which RFA provided pain relief in a patient with metastatic prostate cancer with pain uncontrolled by conventional methods.

  1. Optical generation of radio-frequency power

    SciTech Connect

    Hietala, V.M.; Vawter, G.A.; Brennan, T.M.; Hammons, B.E.; Meyer, W.J.

    1994-11-01

    An optical technique for high-power radio-frequency (RF) signal generation is described. The technique uses a unique photodetector based on a traveling-wave design driven by an appropriately modulated light source. The traveling-wave photodetector (TWPD) exhibits simultaneously a theoretical quantum efficiency approaching 100 % and a very large electrical bandwidth. Additionally, it is capable of dissipating the high-power levels required for the RF generation technique. The modulated light source is formed by either the beating together of two lasers or by the direct modulation of a light source. A system example is given which predicts RF power levels of 100`s of mW`s at millimeter wave frequencies with a theoretical ``wall-plug`` efficiency approaching 34%.

  2. Radiofrequency thermal ablation of renal tumors.

    PubMed

    De Filippo, Massimo; Bozzetti, Francesca; Martora, Rosa; Zagaria, Raffaella; Ferretti, Stefania; Macarini, Luca; Brunese, Luca; Rotondo, Antonio; Rossi, Cristina

    2014-07-01

    Percutaneous radiofrequency ablation (PRFA) of renal malignancies is currently a therapeutic option for patients who are not able to undergo surgery. Some authors consider PRFA as the therapeutic standard in the treatment of renal neoplasms in non-operable patients due to comorbid conditions and in patients with mild-moderate renal failure, to preserve residual renal functionality. The use of PRFA has become more and more widespread due to a rise in the incidental detection of renal cell carcinomas with the ever-increasing use of Imaging for the study of abdominal diseases. Clinical studies indicate that RF ablation is an effective therapy with a low level of risk of complications, which provides good results in selected patients over short and medium term periods of time, however up to now few long-term studies have been carried out which can confirm the effectiveness of PRFA. PMID:25024061

  3. Radio-frequency low-coherence interferometry.

    PubMed

    Fernández-Pousa, Carlos R; Mora, José; Maestre, Haroldo; Corral, Pablo

    2014-06-15

    A method for retrieving low-coherence interferograms, based on the use of a microwave photonics filter, is proposed and demonstrated. The method is equivalent to the double-interferometer technique, with the scanning interferometer replaced by an analog fiber-optics link and the visibility recorded as the amplitude of its radio-frequency (RF) response. As a low-coherence interferometry system, it shows a decrease of resolution induced by the fiber's third-order dispersion (β3). As a displacement sensor, it provides highly linear and slope-scalable readouts of the interferometer's optical path difference in terms of RF, even in the presence of third-order dispersion. In a proof-of-concept experiment, we demonstrate 20-μm displacement readouts using C-band EDFA sources and standard single-mode fiber. PMID:24978555

  4. Radiofrequency Electromagnetic Field Map of Timisoara

    NASA Astrophysics Data System (ADS)

    Stefu, N.; Solyom, I.; Arama, A.

    2015-12-01

    There are many electromagnetic field (EMF) sources nowadays acting simultaneously, especially in urban areas, making the theoretical estimation of electromagnetic power at ground level very difficult. This paper reports on EMF maps built with measurements collected in Timisoara, at various radiofrequencies. A grid of 15×15 squares was built (approximate resolution 400m x 400m) and measurements of the average and maximum values of the electric field E, magnetic field H and total power density S at 0.9, 1.8 and 2.4 GHz were collected in every node of the grid. Positions of the nodes in terms of latitude and longitude were also collected. Maps were built presenting the spatial distribution of the measured quantities over Timisoara. Potential influences of EMF on public health are discussed.

  5. Radio-frequency quadrupole linear accelerator

    SciTech Connect

    Wangler, T.P.; Stokes, R.H.

    1980-01-01

    The radio-frequency quadrupole (RFQ) is a new linear accelerator concept in which rf electric fields are used to focus, bunch, and accelerate the beam. Because the RFQ can provide strong focusing at low velocities, it can capture a high-current dc ion beam from a low-voltage source and accelerate it to an energy of 1 MeV/nucleon within a distance of a few meters. A recent experimental test at the Los Alamos Scientific Laboratory (LASL) has confirmed the expected performance of this structure and has stimulated interest in a wide variety of applications. The general properties of the RFQ are reviewed and examples of applications of this new accelerator are presented.

  6. Multiparametric imaging with heterogeneous radiofrequency fields

    PubMed Central

    Cloos, Martijn A.; Knoll, Florian; Zhao, Tiejun; Block, Kai T.; Bruno, Mary; Wiggins, Graham C.; Sodickson, Daniel K.

    2016-01-01

    Magnetic resonance imaging (MRI) has become an unrivalled medical diagnostic technique able to map tissue anatomy and physiology non-invasively. MRI measurements are meticulously engineered to control experimental conditions across the sample. However, residual radiofrequency (RF) field inhomogeneities are often unavoidable, leading to artefacts that degrade the diagnostic and scientific value of the images. Here we show that, paradoxically, these artefacts can be eliminated by deliberately interweaving freely varying heterogeneous RF fields into a magnetic resonance fingerprinting data-acquisition process. Observations made based on simulations are experimentally confirmed at 7 Tesla (T), and the clinical implications of this new paradigm are illustrated with in vivo measurements near an orthopaedic implant at 3T. These results show that it is possible to perform quantitative multiparametric imaging with heterogeneous RF fields, and to liberate MRI from the traditional struggle for control over the RF field uniformity. PMID:27526996

  7. Multiparametric imaging with heterogeneous radiofrequency fields.

    PubMed

    Cloos, Martijn A; Knoll, Florian; Zhao, Tiejun; Block, Kai T; Bruno, Mary; Wiggins, Graham C; Sodickson, Daniel K

    2016-01-01

    Magnetic resonance imaging (MRI) has become an unrivalled medical diagnostic technique able to map tissue anatomy and physiology non-invasively. MRI measurements are meticulously engineered to control experimental conditions across the sample. However, residual radiofrequency (RF) field inhomogeneities are often unavoidable, leading to artefacts that degrade the diagnostic and scientific value of the images. Here we show that, paradoxically, these artefacts can be eliminated by deliberately interweaving freely varying heterogeneous RF fields into a magnetic resonance fingerprinting data-acquisition process. Observations made based on simulations are experimentally confirmed at 7 Tesla (T), and the clinical implications of this new paradigm are illustrated with in vivo measurements near an orthopaedic implant at 3T. These results show that it is possible to perform quantitative multiparametric imaging with heterogeneous RF fields, and to liberate MRI from the traditional struggle for control over the RF field uniformity. PMID:27526996

  8. Assessment of outdoor radiofrequency electromagnetic field exposure through hotspot localization using kriging-based sequential sampling

    SciTech Connect

    Aerts, Sam Deschrijver, Dirk; Verloock, Leen; Dhaene, Tom; Martens, Luc; Joseph, Wout

    2013-10-15

    In this study, a novel methodology is proposed to create heat maps that accurately pinpoint the outdoor locations with elevated exposure to radiofrequency electromagnetic fields (RF-EMF) in an extensive urban region (or, hotspots), and that would allow local authorities and epidemiologists to efficiently assess the locations and spectral composition of these hotspots, while at the same time developing a global picture of the exposure in the area. Moreover, no prior knowledge about the presence of radiofrequency radiation sources (e.g., base station parameters) is required. After building a surrogate model from the available data using kriging, the proposed method makes use of an iterative sampling strategy that selects new measurement locations at spots which are deemed to contain the most valuable information—inside hotspots or in search of them—based on the prediction uncertainty of the model. The method was tested and validated in an urban subarea of Ghent, Belgium with a size of approximately 1 km{sup 2}. In total, 600 input and 50 validation measurements were performed using a broadband probe. Five hotspots were discovered and assessed, with maximum total electric-field strengths ranging from 1.3 to 3.1 V/m, satisfying the reference levels issued by the International Commission on Non-Ionizing Radiation Protection for exposure of the general public to RF-EMF. Spectrum analyzer measurements in these hotspots revealed five radiofrequency signals with a relevant contribution to the exposure. The radiofrequency radiation emitted by 900 MHz Global System for Mobile Communications (GSM) base stations was always dominant, with contributions ranging from 45% to 100%. Finally, validation of the subsequent surrogate models shows high prediction accuracy, with the final model featuring an average relative error of less than 2 dB (factor 1.26 in electric-field strength), a correlation coefficient of 0.7, and a specificity of 0.96. -- Highlights: • We present an

  9. Auditory response to pulsed radiofrequency energy.

    PubMed

    Elder, J A; Chou, C K

    2003-01-01

    The human auditory response to pulses of radiofrequency (RF) energy, commonly called RF hearing, is a well established phenomenon. RF induced sounds can be characterized as low intensity sounds because, in general, a quiet environment is required for the auditory response. The sound is similar to other common sounds such as a click, buzz, hiss, knock, or chirp. Effective radiofrequencies range from 2.4 to 10000 MHz, but an individual's ability to hear RF induced sounds is dependent upon high frequency acoustic hearing in the kHz range above about 5 kHz. The site of conversion of RF energy to acoustic energy is within or peripheral to the cochlea, and once the cochlea is stimulated, the detection of RF induced sounds in humans and RF induced auditory responses in animals is similar to acoustic sound detection. The fundamental frequency of RF induced sounds is independent of the frequency of the radiowaves but dependent upon head dimensions. The auditory response has been shown to be dependent upon the energy in a single pulse and not on average power density. The weight of evidence of the results of human, animal, and modeling studies supports the thermoelastic expansion theory as the explanation for the RF hearing phenomenon. RF induced sounds involve the perception via bone conduction of thermally generated sound transients, that is, audible sounds are produced by rapid thermal expansion resulting from a calculated temperature rise of only 5 x 10(-6) degrees C in tissue at the threshold level due to absorption of the energy in the RF pulse. The hearing of RF induced sounds at exposure levels many orders of magnitude greater than the hearing threshold is considered to be a biological effect without an accompanying health effect. This conclusion is supported by a comparison of pressure induced in the body by RF pulses to pressure associated with hazardous acoustic energy and clinical ultrasound procedures. PMID:14628312

  10. Process for selected gas oxide removal by radiofrequency catalysts

    DOEpatents

    Cha, Chang Y.

    1993-01-01

    This process to remove gas oxides from flue gas utilizes adsorption on a char bed subsequently followed by radiofrequency catalysis enhancing such removal through selected reactions. Common gas oxides include SO.sub.2 and NO.sub.x.

  11. Radiofrequency catheter ablation in pediatric patients with supraventricular arrhythmias.

    PubMed

    Rhodes, L A; Lobban, J H; Schmidt, S B

    1995-01-01

    Radiofrequency (RF) ablation of foci leading to abnormal cardiac rhythms is rapidly becoming the procedure of choice in the management of arrhythmias in adults. This report reviews our initial experience with RF ablation in the pediatric population. PMID:8533398

  12. The use of radiofrequency catheter ablation to cure dilated cardiomyopathy.

    PubMed

    Schmidt, S B; Lobban, J H; Reddy, S; Hoelper, M; Palmer, D L

    1997-01-01

    Incessant supraventricular tachycardia can cause a dilated cardiomyopathy. This article discusses the case of a 55-year-old woman whose cardiomyopathy was reversed when she underwent successful radiofrequency catheter ablation of a unifocal atrial tachycardia. PMID:9197188

  13. Dynamics Of Ions In A Radio-Frequency Quadrupole Trap

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Williams, Angelyn P.; Maleki, Lutfollah

    1994-01-01

    Report describes computer-simulation study of motions of various numbers of ions in Paul trap. Study part of continuing effort to understand motions of trapped charged particles (atoms, ions, molecules, or dust particles). Motions characterized in terms of heating by radio-frequency fields, formation of crystallike structures in cold clouds of trapped particles, and other phenomena important in operation of radio-frequency traps in frequency standards.

  14. A rare complication of radiofrequency ablation: skin burn.

    PubMed

    Ertuğrul, İlker; Karagöz, Tevfik; Aykan, Hayrettin H

    2015-10-01

    Radiofrequency ablation is the first-line treatment for arrhythmias with high success and low complication rates. Skin burns have been reported rarely after electrophysiological procedures, especially procedures in which higher-power energy is used and multiple ablations are performed. Here, we report a case of skin burn that developed after radiofrequency ablation for ventricular tachycardia originating from the right ventricular outflow tract. PMID:25613639

  15. Treatment of acne vulgaris with fractional radiofrequency microneedling.

    PubMed

    Kim, Sang Tae; Lee, Kang Hoon; Sim, Hyung Jun; Suh, Kee Suck; Jang, Min Soo

    2014-07-01

    Fractional radiofrequency microneedling is a novel radiofrequency technique that uses insulated microneedles to deliver energy to the deep dermis at the point of penetration without destruction of the epidermis. It has been used for the treatment of various dermatological conditions including wrinkles, atrophic scars and hypertrophic scars. There have been few studies evaluating the efficacy of fractional radiofrequency microneedling in the treatment of acne, and none measuring objective parameters like the number of inflammatory and non-inflammatory acne lesions or sebum excretion levels. The safety and efficacy of fractional radiofrequency microneedling in the treatment of acne vulgaris was investigated. In a prospective clinical trial, 25 patients with moderate to severe acne were treated with fractional radiofrequency microneedling. The procedure was carried out three times at 1-month intervals. Acne lesion count, subjective satisfaction score, sebum excretion level and adverse effects were assessed at baseline and at 4, 8 and 12 weeks after the first treatment as well as 4, 8 and 12 weeks after the last treatment. Number of acne lesions (inflammatory and non-inflammatory) decreased. Sebum excretion and subjective satisfaction were more favorable at every time point compared with the baseline values (P < 0.05). Inflammatory lesions responded better than non-inflammatory lesions (P < 0.05). Adverse effects such as pinpoint bleeding, pain and erythema were noted, but were transient and not severe enough to stop treatment. Fractional radiofrequency microneedling is a safe and effective treatment for acne vulgaris. PMID:24807263

  16. Epidemiology of Health Effects of Radiofrequency Exposure

    PubMed Central

    Ahlbom, Anders; Green, Adele; Kheifets, Leeka; Savitz, David; Swerdlow, Anthony

    2004-01-01

    We have undertaken a comprehensive review of epidemiologic studies about the effects of radiofrequency fields (RFs) on human health in order to summarize the current state of knowledge, explain the methodologic issues that are involved, and aid in the planning of future studies. There have been a large number of occupational studies over several decades, particularly on cancer, cardiovascular disease, adverse reproductive outcome, and cataract, in relation to RF exposure. More recently, there have been studies of residential exposure, mainly from radio and television transmitters, and especially focusing on leukemia. There have also been studies of mobile telephone users, particularly on brain tumors and less often on other cancers and on symptoms. Results of these studies to date give no consistent or convincing evidence of a causal relation between RF exposure and any adverse health effect. On the other hand, the studies have too many deficiencies to rule out an association. A key concern across all studies is the quality of assessment of RF exposure. Despite the ubiquity of new technologies using RFs, little is known about population exposure from RF sources and even less about the relative importance of different sources. Other cautions are that mobile phone studies to date have been able to address only relatively short lag periods, that almost no data are available on the consequences of childhood exposure, and that published data largely concentrate on a small number of outcomes, especially brain tumor and leukemia. PMID:15579422

  17. Electromagnetic limits to radiofrequency (RF) neuronal telemetry

    PubMed Central

    Diaz, R. E.; Sebastian, T.

    2013-01-01

    The viability of a radiofrequency (RF) telemetry channel for reporting individual neuron activity wirelessly from an embedded antenna to an external receiver is determined. Comparing the power at the transmitting antenna required for the desired Channel Capacity, to the maximum power that this antenna can dissipate in the body without altering or damaging surrounding tissue reveals the severe penalty incurred by miniaturization of the antenna. Using both Specific Absorption Rate (SAR) and thermal damage limits as constraints, and 300 Kbps as the required capacity for telemetry streams 100 ms in duration, the model shows that conventional antennas smaller than 0.1 mm could not support human neuronal telemetry to a remote receiver (1 m away.) Reducing the antenna to 10 microns in size to enable the monitoring of single human neuron signals to a receiver at the surface of the head would require operating with a channel capacity of only 0.3 bps. PMID:24346503

  18. Carbon Dust Growth in a Radiofrequency Discharge

    SciTech Connect

    Peng, Y.; Hugon, R.; Brochard, F.; Vasseur, J.-L.; Bougdira, J.; Lacroix, D.; Brosset, C.

    2008-03-19

    Plasma wall interactions studies are of primary importance for increasing the life time of the first wall in fusion devices. In ITER, the divertor target plates will receive on a small surface a significant part of the power during operation, and carbon materials will be used. Although carbon has several advantages than the materials used at other places of the plasma chamber (W and Be), they undergo chemical reactions with hydrogen and its isotopes used as fuel for the fusion reaction. Under ITER operating conditions, the high temperature of the wall will promote diffusion and recombination of atomic hydrogen, withholding the fuel. Moreover, carbon atoms produced by erosion may be deposited at other locations, causing further increase of the hydrogen inventory in the vessel, and encountering several subsequent major safety issues.In our experiment, carbon dust formation and growth are studied in a radiofrequency discharge. Dust particles sediment into the cathode sheath using carbon originating either from a graphite cathode in pure argon plasmas or from C{sub 2}H{sub 2} mixed with argon in case where a stainless steel cathode is used. In this contribution, we present a characterization of carbon dust particles under various plasma conditions (pressure, RF power, C{sub 2}H{sub 2} percentage). Dust growth is studied in situ using FTIR spectroscopy, whereas the structural properties of the dust particles are studied ex situ using TEM, SEM, and FTIR.

  19. Near-field radiofrequency electromagnetic exposure assessment.

    PubMed

    Rubtsova, Nina; Perov, Sergey; Belaya, Olga; Kuster, Niels; Balzano, Quirino

    2015-09-01

    Personal wireless telecommunication devices, such as radiofrequency (RF) electromagnetic field (EMF) sources operated in vicinity of human body, have possible adverse health effects. Therefore, the correct EMF assessment is necessary in their near field. According to international near-field measurement criteria, the specific absorption rate (SAR) is used for absorbed energy distribution assessment in tissue simulating liquid phantoms. The aim of this investigation is to validate the relationship between the H-field of incident EMF and absorbed energy in phantoms. Three typical wireless telecommunication system frequencies are considered (900, 1800 and 2450 MHz). The EMF source at each frequency is an appropriate half-wave dipole antenna and the absorbing medium is a flat phantom filled with the suitable tissue simulating liquid. Two methods for SAR estimation have been used: standard procedure based on E-field measured in tissue simulating medium and a proposed evaluation by measuring the incident H-field. Compared SAR estimations were performed for various distances between sources and phantom. Also, these research data were compared with simulation results, obtained by using finite-difference time-domain method. The acquired data help to determine the source near-field space characterized by the smallest deviation between SAR estimation methods. So, this region near the RF source is suitable for correct RF energy absorption assessment using the magnetic component of the RF fields. PMID:26444190

  20. Radiofrequency ablation of intrahepatic cholangiocarcinoma: preliminary experience.

    PubMed

    Carrafiello, Gianpaolo; Laganà, Domenico; Cotta, Elisa; Mangini, Monica; Fontana, Federico; Bandiera, Francesca; Fugazzola, Carlo

    2010-08-01

    The purpose of this study was to evaluate the safety and efficacy of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) in patients with intrahepatic cholangiocarcinoma (ICCA) in a small, nonrandomized series. From February 2004 to July 2008, six patients (four men and two women; mean age 69.8 years [range 48 to 83]) with ICCA underwent percutaneous US-guided RFA. Preintervetional transarterial embolization was performed in two cases to decrease heat dispersion during RFA in order to increase the area of ablation. The efficacy of RFA was evaluated using contrast-enhanced dynamic computed tomography (CT) 1 month after treatment and then every 3 months thereafter. Nine RFA sessions were performed for six solid hepatic tumors in six patients. The duration of follow-up ranged from 13 to 21 months (mean 17.5). Posttreatment CT showed total necrosis in four of six tumors after one or two RFA sessions. Residual tumor was observed in two patients with larger tumors (5 and 5.8 cm in diameter). All patients tolerated the procedure, and there with no major complications. Only 1 patient developed post-RFA syndrome (pain, fever, malaise, and leukocytosis), which resolved with oral administration of acetaminophen. Percutaneous RFA is a safe and effective treatment for patients with hepatic tumors: It is ideally suited for those who are not eligible for surgery. Long-term follow-up data regarding local and systemic recurrence and survival are still needed. PMID:20411389

  1. Radiofrequency ablation of hepatocellular carcinoma: Current status

    PubMed Central

    Minami, Yasunori; Kudo, Masatoshi

    2010-01-01

    Ablation therapy is one of the best curative treatment options for malignant liver tumors, and can be an alternative to resection. Radiofrequency ablation (RFA) of primary and secondary liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and RFA has markedly changed the treatment strategy for small hepatocellular carcinoma (HCC). Percutaneous RFA can achieve the same overall and disease-free survival as surgical resection for patients with small HCC. The use of a laparoscopic or open approach allows repeated placements of RFA electrodes at multiple sites to ablate larger tumors. RFA combined with transcatheter arterial chemoembolization will make the treatment of larger tumors a clinically viable treatment alternative. However, an accurate evaluation of treatment response is very important to secure successful RFA therapy. Since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences, an accurate evaluation of treatment response is very important to secure successful RFA therapy. To minimize complications of RFA, clinicians should be familiar with the imaging features of each type of complication. Appropriate management of complications is essential for successful RFA treatment. PMID:21179308

  2. Radiofrequency plasma polymerized perfluoroionomer membrane materials

    SciTech Connect

    Danilich, M.J.; Gervasio, D.F.; Marchant, R.E.

    1993-12-31

    Ion exchange membranes have received considerable attention in recent years. Applications of ion exchange membranes have included such electrochemical systems as water and organic electrolyzers, redox-flow batteries, and sensors. This work is a study of radiofrequency plasma polymerization of perfluorinated acid-containing monomers and a perfluorinated {open_quotes}backbone{close_quotes} comonomer as a method for synthesizing novel polyionomer film coatings for use as membranes on electrodes and biomedical sensors. The results indicate that, by altering the deposition conditions, some control can be exercised over the retention of acid functional groups by plasma polymers. Using AC impedance measurements, the ionic conductivity of these films was found to be two to four orders of magnitude higher than their aqueous environments. In addition, several of the acid-containing plasma polymerized films were hydrophilic, having an advancing water contact angle of less than fifteen degrees. The initial results of this study have demonstrated the feasibility of using acid-containing plasma polymers as crosslinked membrane materials suitable for use with electrochemical sensors and biosensors.

  3. Radiofrequency Ablation of Intrahepatic Cholangiocarcinoma: Preliminary Experience

    SciTech Connect

    Carrafiello, Gianpaolo Lagana, Domenico; Cotta, Elisa; Mangini, Monica; Fontana, Federico; Bandiera, Francesca; Fugazzola, Carlo

    2010-08-15

    The purpose of this study was to evaluate the safety and efficacy of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) in patients with intrahepatic cholangiocarcinoma (ICCA) in a small, nonrandomized series. From February 2004 to July 2008, six patients (four men and two women; mean age 69.8 years [range 48 to 83]) with ICCA underwent percutaneous US-guided RFA. Preintervetional transarterial embolization was performed in two cases to decrease heat dispersion during RFA in order to increase the area of ablation. The efficacy of RFA was evaluated using contrast-enhanced dynamic computed tomography (CT) 1 month after treatment and then every 3 months thereafter. Nine RFA sessions were performed for six solid hepatic tumors in six patients. The duration of follow-up ranged from 13 to 21 months (mean 17.5). Posttreatment CT showed total necrosis in four of six tumors after one or two RFA sessions. Residual tumor was observed in two patients with larger tumors (5 and 5.8 cm in diameter). All patients tolerated the procedure, and there with no major complications. Only 1 patient developed post-RFA syndrome (pain, fever, malaise, and leukocytosis), which resolved with oral administration of acetaminophen. Percutaneous RFA is a safe and effective treatment for patients with hepatic tumors: It is ideally suited for those who are not eligible for surgery. Long-term follow-up data regarding local and systemic recurrence and survival are still needed.

  4. Radiofrequency Heating Pathways for Gold Nanoparticles

    PubMed Central

    Collins, C. B.; McCoy, R. S.; Ackerson, B. J.; Collins, G. J.

    2015-01-01

    This feature article reviews the thermal dissipation of nanoscopic gold under radiofrequency (RF) irradiation. It also presents previously unpublished data addressing obscure aspects of this phenomenon. While applications in biology motivated initial investigation of RF heating of gold nanoparticles, recent controversy concerning whether thermal effects can be attributed to nanoscopic gold highlight the need to understand the involved mechanism or mechanisms of heating. Both the nature of the particle and the nature of the RF field influence heating. Aspects of nanoparticle chemistry and physics, including the hydrodynamic diameter of the particle, the oxidation state and related magnetism of the core, and the chemical nature of the ligand shell may all strongly influence to what extent a nanoparticle heats in an RF field. Aspects of RF include: power, frequency and antenna designs that emphasize relative strength of magnetic or electric fields, and also influence the extent to which a gold nanoparticle heats in RF. These nanoparticle and RF properties are analysed in the context of three heating mechanisms proposed to explain gold nanoparticle heating in an RF field. This article also makes a critical analysis of the existing literature in the context of the nanoparticle preparations, RF structure, and suggested mechanisms in previously reported experiments. PMID:24962620

  5. Radiofrequency heating pathways for gold nanoparticles.

    PubMed

    Collins, C B; McCoy, R S; Ackerson, B J; Collins, G J; Ackerson, C J

    2014-08-01

    This feature article reviews the thermal dissipation of nanoscopic gold under radiofrequency (RF) irradiation. It also presents previously unpublished data addressing obscure aspects of this phenomenon. While applications in biology motivated initial investigation of RF heating of gold nanoparticles, recent controversy concerning whether thermal effects can be attributed to nanoscopic gold highlight the need to understand the involved mechanism or mechanisms of heating. Both the nature of the particle and the nature of the RF field influence heating. Aspects of nanoparticle chemistry which may affect thermal dissipation include the hydrodynamic diameter of the particle, the oxidation state and related magnetism of the core, and the chemical nature of the ligand shell. Aspects of RF which may affect thermal dissipation include power, frequency and antenna designs that emphasize relative strength of magnetic or electric fields. These nanoparticle and RF properties are analysed in the context of three heating mechanisms proposed to explain gold nanoparticle heating in an RF field. This article also makes a critical analysis of the existing literature in the context of the nanoparticle preparations, RF structure, and suggested mechanisms in previously reported experiments. PMID:24962620

  6. Radiofrequency treatment alters cancer cell phenotype

    NASA Astrophysics Data System (ADS)

    Ware, Matthew J.; Tinger, Sophia; Colbert, Kevin L.; Corr, Stuart J.; Rees, Paul; Koshkina, Nadezhda; Curley, Steven; Summers, H. D.; Godin, Biana

    2015-07-01

    The importance of evaluating physical cues in cancer research is gradually being realized. Assessment of cancer cell physical appearance, or phenotype, may provide information on changes in cellular behavior, including migratory or communicative changes. These characteristics are intrinsically different between malignant and non-malignant cells and change in response to therapy or in the progression of the disease. Here, we report that pancreatic cancer cell phenotype was altered in response to a physical method for cancer therapy, a non-invasive radiofrequency (RF) treatment, which is currently being developed for human trials. We provide a battery of tests to explore these phenotype characteristics. Our data show that cell topography, morphology, motility, adhesion and division change as a result of the treatment. These may have consequences for tissue architecture, for diffusion of anti-cancer therapeutics and cancer cell susceptibility within the tumor. Clear phenotypical differences were observed between cancerous and normal cells in both their untreated states and in their response to RF therapy. We also report, for the first time, a transfer of microsized particles through tunneling nanotubes, which were produced by cancer cells in response to RF therapy. Additionally, we provide evidence that various sub-populations of cancer cells heterogeneously respond to RF treatment.

  7. Current oncologic applications of radiofrequency ablation therapies

    PubMed Central

    Shah, Dhruvil R; Green, Sari; Elliot, Angelina; McGahan, John P; Khatri, Vijay P

    2013-01-01

    Radiofrequency ablation (RFA) uses high frequency alternating current to heat a volume of tissue around a needle electrode to induce focal coagulative necrosis with minimal injury to surrounding tissues. RFA can be performed via an open, laparoscopic, or image guided percutaneous approach and be performed under general or local anesthesia. Advances in delivery mechanisms, electrode designs, and higher power generators have increased the maximum volume that can be ablated, while maximizing oncological outcomes. In general, RFA is used to control local tumor growth, prevent recurrence, palliate symptoms, and improve survival in a subset of patients that are not candidates for surgical resection. It’s equivalence to surgical resection has yet to be proven in large randomized control trials. Currently, the use of RFA has been well described as a primary or adjuvant treatment modality of limited but unresectable hepatocellular carcinoma, liver metastasis, especially colorectal cancer metastases, primary lung tumors, renal cell carcinoma, boney metastasis and osteoid osteomas. The role of RFA in the primary treatment of early stage breast cancer is still evolving. This review will discuss the general features of RFA and outline its role in commonly encountered solid tumors. PMID:23671734

  8. Radiofrequency treatments: what can we expect?

    PubMed

    Avantaggiato, A; Bertuzzi, G; Addonisio, T; Iannucci, G; Vitiello, U; Carinci, F

    2016-01-01

    Among non-ablative procedures in aesthetic medicine, the radiofrequency (RF) is one of the most popular for the treatment of face and body skin laxity. It can be classified as a physical bio-stimulation that produces a temperature increase on biological structures, using electromagnetic waves. The term encompasses devices having substantial differences in energy, wavelengths, handpieces dimension and structure. Moreover, for some of these, the protocols are only partially defined. The aim of this short review is to clarify some aspecst of the RF therapy starting from the physics, passing through the mechanism of action and finally, with the most suitable protocols. Contrary to mechanic waves, electromagnetic waves, physics are always transversal to the impulse and this leads to the different energy distribution in capacitive (monopolar) or resistive (bi- or multi-polar) applications. The thermal damage as therapeutic effect is a postulate that needs to be discussed and the same is true for the terms “non-surgical” and “non-ablative”, often recurrent in the scientific literature. Protocols must be optimized according to the machine and the patient, keeping in mind the possibilities of biostimulation in terms of immediate improvement and of long lasting investment in skin rejuvenation. It is mandatory to understand the possibilities and limitations of each device to perform useful, safe and correct medical treatments. PMID:27469571

  9. Radiofrequency treatment alters cancer cell phenotype

    PubMed Central

    Ware, Matthew J.; Tinger, Sophia; Colbert, Kevin L.; Corr, Stuart J.; Rees, Paul; Koshkina, Nadezhda; Curley, Steven; Summers, H. D.; Godin, Biana

    2015-01-01

    The importance of evaluating physical cues in cancer research is gradually being realized. Assessment of cancer cell physical appearance, or phenotype, may provide information on changes in cellular behavior, including migratory or communicative changes. These characteristics are intrinsically different between malignant and non-malignant cells and change in response to therapy or in the progression of the disease. Here, we report that pancreatic cancer cell phenotype was altered in response to a physical method for cancer therapy, a non-invasive radiofrequency (RF) treatment, which is currently being developed for human trials. We provide a battery of tests to explore these phenotype characteristics. Our data show that cell topography, morphology, motility, adhesion and division change as a result of the treatment. These may have consequences for tissue architecture, for diffusion of anti-cancer therapeutics and cancer cell susceptibility within the tumor. Clear phenotypical differences were observed between cancerous and normal cells in both their untreated states and in their response to RF therapy. We also report, for the first time, a transfer of microsized particles through tunneling nanotubes, which were produced by cancer cells in response to RF therapy. Additionally, we provide evidence that various sub-populations of cancer cells heterogeneously respond to RF treatment. PMID:26165830

  10. Magnetoreception in birds: the effect of radio-frequency fields.

    PubMed

    Wiltschko, Roswitha; Thalau, Peter; Gehring, Dennis; Nießner, Christine; Ritz, Thorsten; Wiltschko, Wolfgang

    2015-02-01

    The avian magnetic compass, probably based on radical pair processes, works only in a narrow functional window around the local field strength, with cryptochrome 1a as most likely receptor molecule. Radio-frequency fields in the MHz range have been shown to disrupt the birds' orientation, yet the nature of this interference is still unclear. In an immuno-histological study, we tested whether the radio-frequency fields interfere with the photoreduction of cryptochrome, but this does not seem to be the case. In behavioural studies, birds were not able to adjust to radio-frequency fields like they are able to adjust to static fields outside the normal functional range: neither a 2-h pre-exposure in a 7.0 MHz field, 480 nT, nor a 7-h pre-exposure in a 1.315 MHz field, 15 nT, allowed the birds to regain their orientation ability. This inability to adjust to radio-frequency fields suggests that these fields interfere directly with the primary processes of magnetoreception and therefore disable the avian compass as long as they are present. They do not have lasting adverse after-effects, however, as birds immediately after exposure to a radio-frequency field were able to orient in the local geomagnetic field. PMID:25540238

  11. Magnetoreception in birds: the effect of radio-frequency fields

    PubMed Central

    Wiltschko, Roswitha; Thalau, Peter; Gehring, Dennis; Nießner, Christine; Ritz, Thorsten; Wiltschko, Wolfgang

    2015-01-01

    The avian magnetic compass, probably based on radical pair processes, works only in a narrow functional window around the local field strength, with cryptochrome 1a as most likely receptor molecule. Radio-frequency fields in the MHz range have been shown to disrupt the birds' orientation, yet the nature of this interference is still unclear. In an immuno-histological study, we tested whether the radio-frequency fields interfere with the photoreduction of cryptochrome, but this does not seem to be the case. In behavioural studies, birds were not able to adjust to radio-frequency fields like they are able to adjust to static fields outside the normal functional range: neither a 2-h pre-exposure in a 7.0 MHz field, 480 nT, nor a 7-h pre-exposure in a 1.315 MHz field, 15 nT, allowed the birds to regain their orientation ability. This inability to adjust to radio-frequency fields suggests that these fields interfere directly with the primary processes of magnetoreception and therefore disable the avian compass as long as they are present. They do not have lasting adverse after-effects, however, as birds immediately after exposure to a radio-frequency field were able to orient in the local geomagnetic field. PMID:25540238

  12. Radiofrequency for the treatment of skin laxity: mith or truth.

    PubMed

    Araújo, Angélica Rodrigues de; Soares, Viviane Pinheiro Campos; Silva, Fernanda Souza da; Moreira, Tatiane da Silva

    2015-01-01

    The nonablative radiofrequency is a procedure commonly used for the treatment of skin laxity from an increase in tissue temperature. The goal is to induce thermal damage to thus stimulate neocollagenesis in deep layers of the skin and subcutaneous tissue. However, many of these devices haven't been tested and their parameters are still not accepted by the scientific community. Because of this, it is necessary to review the literature regarding the physiological effects and parameters for application of radiofrequency and methodological quality and level of evidence of studies. A literature search was performed in MEDLINE, PEDro, SciELO, PubMed, LILACS and CAPES and experimental studies in humans, which used radiofrequency devices as treatment for facial or body laxity, were selected. The results showed that the main physiological effect is to stimulate collagen synthesis. There was no homogeneity between studies in relation to most of the parameters used and the methodological quality of studies and level of evidence for using radiofrequency are low. This fact complicates the determination of effective parameters for clinical use of this device in the treatment of skin laxity. The analyzed studies suggest that radiofrequency is effective, however the physiological mechanisms and the required parameters are not clear in the literature. PMID:26560216

  13. Radiofrequency for the treatment of skin laxity: mith or truth*

    PubMed Central

    de Araújo, Angélica Rodrigues; Soares, Viviane Pinheiro Campos; da Silva, Fernanda Souza; Moreira, Tatiane da Silva

    2015-01-01

    The nonablative radiofrequency is a procedure commonly used for the treatment of skin laxity from an increase in tissue temperature. The goal is to induce thermal damage to thus stimulate neocollagenesis in deep layers of the skin and subcutaneous tissue. However, many of these devices haven't been tested and their parameters are still not accepted by the scientific community. Because of this, it is necessary to review the literature regarding the physiological effects and parameters for application of radiofrequency and methodological quality and level of evidence of studies. A literature search was performed in MEDLINE, PEDro, SciELO, PubMed, LILACS and CAPES and experimental studies in humans, which used radiofrequency devices as treatment for facial or body laxity, were selected. The results showed that the main physiological effect is to stimulate collagen synthesis. There was no homogeneity between studies in relation to most of the parameters used and the methodological quality of studies and level of evidence for using radiofrequency are low. This fact complicates the determination of effective parameters for clinical use of this device in the treatment of skin laxity. The analyzed studies suggest that radiofrequency is effective, however the physiological mechanisms and the required parameters are not clear in the literature. PMID:26560216

  14. The link between radiofrequencies emitted from wireless technologies and oxidative stress.

    PubMed

    Dasdag, Suleyman; Akdag, Mehmet Zulkuf

    2016-09-01

    Wireless communication such as cellular telephones and other types of handheld phones working with frequencies of 900MHz, 1800MHz, 2100MHz, 2450MHz have been increasing rapidly. Therefore, public opinion concern about the potential human health hazards of short and long-term effect of exposure to radiofrequency (RF) radiation. Oxidative stress is a biochemical condition, which is defined by the imbalance between reactive oxygen species (ROS) and the anti-oxidative defense. In this review, we evaluated available in vitro and in vivo studies carried out on the relation between RF emitted from mobile phones and oxidative stress. The results of the studies we reviewed here indicated that mobile phones and similar equipment or radars can be thought as a factor, which cause oxidative stress. Even some of them claimed that oxidative stress originated from radiofrequencies can be resulted with DNA damage. For this reason one of the points to think on is relation between mobile phones and oxidative stress. However, more performance is necessary especially on human exposure studies. PMID:26371078

  15. The Precautionary Principle in the Context of Mobile Phone and Base Station Radiofrequency Exposures

    PubMed Central

    Dolan, Mike; Rowley, Jack

    2009-01-01

    Background No health hazard has been established from exposure to radiofrequency fields up to the levels recommended by the International Commission on Non-Ionizing Radiation Protection. However, in response to public concern and the perceived level of scientific uncertainty, there are continuing calls for the application of the precautionary principle to radiofrequency exposures from mobile phones and base stations. Objective We examined the international evolution of calls for precautionary measures in relation to mobile phones and base stations, with particular focus on Australia and the United Kingdom. Results The precautionary principle is difficult to define, and there is no widespread agreement as to how it should be implemented. However, there is a strong argument that precautionary measures should not be implemented in the absence of reliable scientific data and logical reasoning pointing to a possible health hazard. There is also experimental evidence that precautionary advice may increase public concern. Conclusion We argue that conservative exposure standards, technical features that minimize unnecessary exposures, ongoing research, regular review of standards, and availability of consumer information make mobile communications inherently precautionary. Commonsense measures can be adopted by individuals, governments, and industry to address public concern while ensuring that mobile networks are developed for the benefit of society. PMID:19750093

  16. Endoscopic radiofrequency ablation for malignant biliary strictures

    PubMed Central

    WANG, FEI; LI, QUANPENG; ZHANG, XIUHUA; JIANG, GUOBING; GE, XIANXIU; YU, HONG; NIE, JUNJIE; JI, GUOZHONG; MIAO, LIN

    2016-01-01

    Endoscopic radiofrequency ablation (RFA) is a novel palliation therapy for malignant biliary stricture; however, its feasibility and safety has not yet been clearly defined. The aim of the present study was to evaluate the feasibility and safety of endoscopic RFA for the treatment of malignant biliary strictures. A total of 12 patients treated by endoscopic RFA between December 2011 and October 2013 were retrospectively analyzed. Adverse events within 30 days post-intervention, stricture diameters prior to and following RFA, stent patency and survival time were investigated. A total of 12 patients underwent 20 RFA procedures as a treatment for malignant biliary strictures. Two patients required repeated elective RFA (4 and 6 times, respectively). All 20 RFA procedures were successfully performed without technical problems. During a 30 day period following each RFA procedure, two patients experienced fever (38.2 and 38.9°C, respectively) and another patient exhibited post-endoscopic retrograde cholangiopancreatography pancreatitis. The 30- and 90-day mortality rates were 0 and 8.3%, respectively. Mean stricture diameter prior to RFA was 5.3 mm (standard deviation (SD), 0.9 mm; range, 5–8 mm), and the mean diameter following RFA was 12.6 mm (SD, 3.1 mm; range, 8–15 mm). There was a significant increase of 7.3 mm in the bile duct diameter following RFA in comparison with prior to RFA (t=8.6; P≤0.001). Of the 11 patients with stents inserted following RFA, the median stent patency was 125.0 days [95% confidence interval (CI), 94.7–155.3 days]. Extrapolated median survival following the first RFA was 232 days (95% CI, 94.3–369.7 days). In conclusion, RFA appears to be an efficient and safe treatment strategy for the palliation of unresectable malignant biliary strictures. PMID:27284336

  17. Quantitative calibration of radiofrequency NMR Stark effects

    NASA Astrophysics Data System (ADS)

    Tarasek, Matthew R.; Kempf, James G.

    2011-10-01

    Nuclear magnetic resonance (NMR) Stark responses can occur in quadrupolar nuclei for an electric field oscillating at twice the usual NMR frequency (2ω0). Calibration of responses to an applied E field is needed to establish nuclear spins as probes of native E fields within material and molecular systems. We present an improved approach and apparatus for accurate measurement of quadrupolar Stark effects. Updated values of C14 (the response parameter in cubic crystals) were obtained for both 69Ga and 75As in GaAs. Keys to improvement include a modified implementation of voltage dividers to assess the 2ω0 amplitude, |E|, and the stabilization of divider response by reduction of stray couplings in 2ω0 circuitry. Finally, accuracy was enhanced by filtering sets of |E| through a linear response function that we established for the radiofrequency amplifier. Our approach is verified by two types of spectral results. Steady-state 2ω0 excitation to presaturate NMR spectra yielded C14 = (2.59 ± 0.06) × 1012 m-1 for 69Ga at room-temperature and 14.1 T. For 75As, we obtained (3.1 ± 0.1) × 1012 m-1. Both values reconcile with earlier results from 77 K and below 1 T, whereas current experiments are at room temperature and 14.1 T. Finally, we present results where few-microsecond pulses of the 2ω0 field induced small (tens of Hz) changes in high-resolution NMR line shapes. There too, spectra collected vs |E| agree with the model for response, further establishing the validity of our protocols to specify |E|.

  18. Radiofrequency Cauterization with Biopsy Introducer Needle

    PubMed Central

    Pritchard, William F.; Wray-Cahen, Diane; Karanian, John W.; Hilbert, Stephen; Wood, Bradford J.

    2014-01-01

    PURPOSE The principal risks of needle biopsy are hemorrhage and implantation of tumor cells in the needle tract. This study compared hemorrhage after liver and kidney biopsy with and without radiofrequency (RF) ablation of the needle tract. MATERIALS AND METHODS Biopsies of liver and kidney were performed in swine through introducer needles modified to allow RF ablation with the distal 2 cm of the needle. After each biopsy, randomization determined whether the site was to undergo RF ablation during withdrawal of the introducer needle. Temperature was measured with a thermistor stylet near the needle tip, with a target temperature of 70°C–100°C with RF ablation. Blood loss was measured as grams of blood absorbed in gauze at the puncture site for 2 minutes after needle withdrawal. Selected specimens were cut for gross examination. RESULTS RF ablation reduced bleeding compared with absence of RF ablation in liver and kidney (P < .01), with mean blood loss reduced 63% and 97%, respectively. Mean amounts of blood loss (±SD) in the liver in the RF and no-RF groups were 2.03 g ± 4.03 (CI, 0.53–3.54 g) and 5.50 g ± 5.58 (CI, 3.33–7.66 g), respectively. Mean amounts of blood loss in the kidney in the RF and no-RF groups were 0.26 g ± 0.32 (CI, −0.01 to 0.53 g) and 8.79 g ± 7.72 (CI, 2.34–15.24 g), respectively. With RF ablation, thermal coagulation of the tissue surrounding the needle tract was observed. CONCLUSION RF ablation of needle biopsy tracts reduced hemorrhage after biopsy in the liver and kidney and may reduce complications of hemorrhage as well as implantation of tumor cells in the tract. PMID:14963187

  19. Photoacoustic characterization of radiofrequency ablation lesions

    NASA Astrophysics Data System (ADS)

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

    2012-02-01

    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

  20. Saline-Linked Surface Radiofrequency Ablation

    PubMed Central

    Topp, Stefan A.; McClurken, Michael; Lipson, David; Upadhya, Gundumi A.; Ritter, Jon H.; Linehan, David; Strasberg, Steven M.

    2004-01-01

    Summary Background Data: Saline-linked surface radiofrequency (RF) ablation is a new technique for applying RF energy to surfaces. The surface is cooled, which prevents charring and results in deeper coagulation. However, subsurface heating may lead to steam formation and a form of tissue disruption called steam popping. We determined parameters that predict steam popping and depth of tissue destruction under nonpopping conditions. A commercially available saline-linked surface RF cautery device (Floating Ball 3.0, TissueLink, Inc.) was used. Methods: One hundred eighty circular lesions were created varying in lesion diameter, duration, power, and inflow occlusion. Variables affecting popping were determined. Then factors influencing lesion depth were studied at fixed nonpopping diameter/power combinations (1 cm/10W, 2 cm/15W, 4 cm/60W). Tissue viability was determined in selected samples by staining of tissue NADH. Results: The probability of steam popping was directly related to power level and inflow occlusion, and indirectly related to lesion diameter. Depth of injury under safe nonpopping conditions was directly related to power, lesion size, and inflow occlusion. Maximum depth in excess of 20 mm was achieved using a 4 cm diameter at 60W with inflow occlusion. Microscopy of NADH-stained tissues showed a complete cell killing in the macroscopically visible coagulated area. Conclusions: Steam popping can be avoided by selecting power level/lesion diameter combinations. Tissue destruction to 20 mm can be safely achieved with short periods of inflow occlusion. The device has promise as a treatment of superficial tumors and close resection margins. PMID:15024313

  1. 21 CFR 880.6300 - Implantable radiofrequency transponder system for patient identification and health information.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Implantable radiofrequency transponder system for... radiofrequency transponder system for patient identification and health information. (a) Identification. An implantable radiofrequency transponder system for patient identification and health information is a...

  2. 21 CFR 880.6300 - Implantable radiofrequency transponder system for patient identification and health information.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Implantable radiofrequency transponder system for... radiofrequency transponder system for patient identification and health information. (a) Identification. An implantable radiofrequency transponder system for patient identification and health information is a...

  3. 21 CFR 880.6300 - Implantable radiofrequency transponder system for patient identification and health information.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Implantable radiofrequency transponder system for... radiofrequency transponder system for patient identification and health information. (a) Identification. An implantable radiofrequency transponder system for patient identification and health information is a...

  4. 21 CFR 880.6300 - Implantable radiofrequency transponder system for patient identification and health information.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... radiofrequency transponder system for patient identification and health information. (a) Identification. An implantable radiofrequency transponder system for patient identification and health information is a device... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Implantable radiofrequency transponder system...

  5. Successful Management of Atrio-Esophageal Fistula after Cardiac Radiofrequency Catheter Ablation

    PubMed Central

    Shim, Hun Bo; Kim, Chilsung; Kim, Hong-Kwan

    2013-01-01

    An increase in cardiac radiofrequency catheter ablation for treating refractory atrial fibrillation has resulted in an increased prevalence of complications. Among numerous complications of radiofrequency catheter ablation, atrio-esophageal fistula, although rare, is known to have fatal results. We report a case of successful management of an atrio-esophageal fistula as a complication of cardiac radiofrequency catheter ablation. PMID:23614102

  6. Radiofrequency amplifier based on a dc superconducting quantum interference device

    DOEpatents

    Hilbert, C.; Martinis, J.M.; Clarke, J.

    1984-04-27

    A low noise radiofrequency amplifer, using a dc SQUID (superconducting quantum interference device) as the input amplifying element. The dc SQUID and an input coil are maintained at superconductivity temperatures in a superconducting shield, with the input coil inductively coupled to the superconducting ring of the dc SQUID. A radiofrequency signal from outside the shield is applied to the input coil, and an amplified radiofrequency signal is developed across the dc SQUID ring and transmitted to exteriorly of the shield. A power gain of 19.5 +- 0.5 dB has been achieved with a noise temperature of 1.0 +- 0.4 K at a frequency of 100 MHz.

  7. Radiofrequency amplifier based on a dc superconducting quantum interference device

    DOEpatents

    Hilbert, Claude; Martinis, John M.; Clarke, John

    1986-01-01

    A low noise radiofrequency amplifier (10), using a dc SQUID (superconducting quantum interference device) as the input amplifying element. The dc SQUID (11) and an input coil (12) are maintained at superconductivity temperatures in a superconducting shield (13), with the input coil (12) inductively coupled to the superconducting ring (17) of the dc SQUID (11). A radiofrequency signal from outside the shield (13) is applied to the input coil (12), and an amplified radiofrequency signal is developed across the dc SQUID ring (17) and transmitted to exteriorly of the shield (13). A power gain of 19.5.+-.0.5 dB has been achieved with a noise temperature of 1.0.+-.0.4 K. at a frequency of 100 MHz.

  8. Histopomorphic Evaluation of Radiofrequency Mediated Débridement Chondroplasty

    PubMed Central

    Ganguly, Kumkum; McRury, Ian D; Goodwin, Peter M; Morgan, Roy E; Augé II, Wayne K

    2010-01-01

    The use of radiofrequency devices has become widespread for surgical ablation procedures. When ablation devices have been deployed in treatment settings requiring tissue preservation like débridement chondroplasty, adoption has been limited due to the collateral damage caused by these devices in healthy tissue surrounding the treatment site. Ex vivo radiofrequency mediated débridement chondroplasty was performed on osteochondral specimens demonstrating surface fibrillation obtained from patients undergoing knee total joint replacement. Three radiofrequency systems designed to perform débridement chondroplasty were tested each demonstrating different energy delivery methods: monopolar ablation, bipolar ablation, and non-ablation energy. Treatment outcomes were compared with control specimens as to clinical endpoint and histopomorphic characteristics. Fibrillated cartilage was removed in all specimens; however, the residual tissue remaining at the treatment site displayed significantly different characteristics attributable to radiofrequency energy delivery method. Systems that delivered ablation-based energies caused tissue necrosis and collateral damage at the treatment site including corruption of cartilage Superficial and Transitional Zones; whereas, the non-ablation system created a smooth articular surface with Superficial Zone maintenance and without chondrocyte death or tissue necrosis. The mechanism of radiofrequency energy deposition upon tissues is particularly important in treatment settings requiring tissue preservation. Ablation-based device systems can cause a worsened state of articular cartilage from that of pre-treatment. Non-ablation energy can be successful in modifying/preconditioning tissue during débridement chondroplasty without causing collateral damage. Utilizing a non-ablation radiofrequency system provides the ability to perform successful débridement chondroplasty without causing additional articular cartilage tissue damage and may

  9. Adaptive Response in Mice Exposed to 900 MHz Radiofrequency Fields: Primary DNA Damage

    PubMed Central

    Zhou, Zhen; Zhang, Jie; Tong, Jian; Cao, Yi

    2012-01-01

    The phenomenon of adaptive response (AR) in animal and human cells exposed to ionizing radiation is well documented in scientific literature. We have examined whether such AR could be induced in mice exposed to non-ionizing radiofrequency fields (RF) used for wireless communications. Mice were pre-exposed to 900 MHz RF at 120 µW/cm2 power density for 4 hours/day for 1, 3, 5, 7 and 14 days and then subjected to an acute dose of 3 Gy γ-radiation. The primary DNA damage in the form of alkali labile base damage and single strand breaks in the DNA of peripheral blood leukocytes was determined using the alkaline comet assay. The results indicated that the extent of damage in mice which were pre-exposed to RF for 1 day and then subjected to γ-radiation was similar and not significantly different from those exposed to γ-radiation alone. However, mice which were pre-exposed to RF for 3, 5, 7 and 14 days showed progressively decreased damage and was significantly different from those exposed to γ-radiation alone. Thus, the data indicated that RF pre-exposure is capable of inducing AR and suggested that the pre-exposure for more than 4 hours for 1 day is necessary to elicit such AR. PMID:22389679

  10. Endovenous radiofrequency ablation for the treatment of varicose veins

    PubMed Central

    Kayssi, Ahmed; Pope, Marc; Vucemilo, Ivica; Werneck, Christiane

    2015-01-01

    Summary Varicose veins are a common condition that can be treated surgically. Available operative modalities include saphenous venous ligation and stripping, phlebectomy, endovenous laser therapy and radiofrequency ablation. Radiofrequency ablation is the newest of these technologies, and to our knowledge our group was the first to use it in Canada. Our experience suggests that it is a safe and effective treatment for varicose veins, with high levels of patient satisfaction reported at short-term follow-up. More studies are needed to assess long-term effectiveness and compare the various available treatment options for varicose veins. PMID:25799244

  11. Assessing personal exposures to environmental radiofrequency electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Mann, Simon

    2010-11-01

    Recent advances in the capability of body-worn instruments for measuring the strengths of environmental radiofrequency signals have opened up a range of exciting new research possibilities. The readings from these instruments can be used in health related studies, but they have to be considered carefully when developing exposure metrics, as does the physical dosimetry concerning interactions between radio waves and the body. Several studies have distributed the instruments to large groups of people and analysed the gathered data in relation to possible determinants of exposure. This article reviews the state of the art in personal exposure measurements at radiofrequencies.

  12. Successful treatment of hepatic oligometastases with stereotactic ablative radiotherapy and radiofrequency ablation in an anaplastic lymphoma kinase fusion-positive lung cancer patient.

    PubMed

    Weber, Britta; Liu, Mitchell; Sobkin, Paul; Morris, Stephan W; Hout, David; van der Westhuizen, Nicholas; Tonseth, R Petter; Saltman, David L

    2016-03-01

    Local ablative therapy with stereotactic ablative radiotherapy may improve survival in oncogene-addicted lung cancer patients with extracranial oligometastatic disease treated with targeted therapies. There is limited data on the use of radiofrequency ablation (RFA) in this same setting. We present a case of an anaplastic lymphoma kinase (ALK)-positive lung cancer patient with hepatic oligometastatic progression who was successfully treated with both stereotactic ablative radiation and RFA while continuing with an ALK inhibitor. PMID:27087977

  13. High sensitivity detection of radio-frequency modulated magnetic moment in semiconductors.

    PubMed

    Guite, Chinkhanlun; Venkataraman, V

    2011-10-01

    An experimental setup has been realized to measure weak magnetic moments which can be modulated at radio frequencies (~1-5 MHz). Using an optimized radio-frequency (RF) pickup coil and lock-in amplifier, an experimental sensitivity of 10(-15) Am(2) corresponding to 10(-18) emu has been demonstrated with a 1 s time constant. The detection limit at room temperature is 9.3 × 10(-16) Am(2)/√Hz limited by Johnson noise of the coil. The setup has been used to directly measure the magnetic moment due to a small number (~7 × 10(8)) of spin polarized electrons generated by polarization modulated optical radiation in GaAs and Ge. PMID:22047310

  14. Linewidth of single laser-cooled 24Mg+ ion in radiofrequency trap

    PubMed Central

    Nagourney, W.; Janik, G.; Dehmelt, H.

    1983-01-01

    A single Mg+ has been successfully trapped and cooled in a small radiofrequency trap. The ion was cooled by using the radiation from a single-frequency ring dye laser whose output was doubled in frequency with an NH42H2PO4 temperature phasematched crystal; a power of about 22 μW or less was sufficient for all of the experiments. The ion temperature was estimated by a computer fit of the experimental resonance line profile; the resulting linewidth was compared to previously published Mg+ 32P3/2 Hanle-effect linewidths. The result is a temperature of 5-5+15 mK, which is lower than that attained previously. PMID:16593275

  15. [Stereotactic Radiofrequency Ablation (SRFA) of intrahepatic cholangiocellular carcinomas: a minimal invasive alternative to liver resection].

    PubMed

    Bale, Reto; Schullian, Peter; Haidu, Marion; Widmann, Gerlig

    2013-03-01

    Up to now resection and liver transplantation are concerned as the only curative treatment options for intrahepatic cholangiocellular carcinomas (ICCs). For patients with inoperable ICCs systemic chemotherapy and various locoregional therapies including transarterial (chemo)embolization (TACE), selective internal radiation therapy (SIRT), radiofrequency ablation (RFA) and microwave ablation (MWA) are applied. Stereotactic RFA (SRFA) allows for precise 3D planning and positioning of multiple RF electrodes. Due to overlapping necroses tumors > 5 cm can be completely ablated in one session. 17 inoperable consecutive patients with 52 ICCs were treated with stereotactic RFA (SRFA). A median overall survival of 60 months was achieved. The two largest tumors with diameters > 10 cm were completely ablated. These SRFA data of irresectable ICCs are superior to the published data on resection. SRFA is a minimal invasive alternative treatment to resection and may be considered as the first-line local treatment of patients with ICCs in selected patients. PMID:23392811

  16. Pulsed Radiofrequency Ablation Under Ultrasound Guidance for Huge Neuroma

    PubMed Central

    Jung, Il; Lee, Chang Hee; Kim, Se Hun; Kim, Jin Sun; Yoo, Byoung Woo

    2014-01-01

    Amputation neuroma can cause very serious, intractable pain. Many treatment modalities are suggested for painful neuroma. Pharmacologic treatment shows a limited effect on eliminating the pain, and surgical treatment has a high recurrence rate. We applied pulsed radiofrequency treatment at the neuroma stalk under ultrasonography guidance. The long-term outcome was very successful, prompting us to report this case. PMID:25031817

  17. A technique for periorbital syringomas: intralesional radiofrequency ablation

    PubMed Central

    Huang, Li-Ping; Zhang, Leng; Wang, Xing-Lin; Liu, Xiao-Cui; Jiang, Tian-Yu; Lin, Bi-Weng

    2012-01-01

    AIM To evaluate the efficacy of intralesional radiofrequency ablation in the treatment of periorbital syringomas. METHODS We tried the intralesional radiofrequency ablation for 64 patients with periorbital syringomas from 2007 to 2011. The operation was performed under 2.5 loupe magnifications. The handpiece was assembled with a needle electrode and connected to the radiofrequency ablation apparatus. The electrode was then inserted into the target lesions in dermis and delivering injury to the base of these tumors. Results were assessed clinically by comparing pre- and post-treatment photographs and patient satisfaction rates. RESULTS Clinical improvement increased with each subsequent treatment session. The percent of patients whose clinic improvement grade were≥3 after each session was respectively 71.9%(Session1), 83.3%(Session2), and 100%(Session3). The statistical results indicated the concordance of the clinical assessment and the satisfaction level of patients (kappa=0.78 of the session1; kappa=0.82 of the session2). The majority of patients had good or excellent cosmetic results. Postoperatively, there were no permanent side effects or recurrences. CONCLUSION As a new technique of minimally invasion, the intralesional radiofrequency ablation was found to be an effective, inexpensive, highly precise and safe way of treating periorbital syringomas. PMID:22762046

  18. The imprint of radiofrequency in the management of hepatocellular carcinoma

    PubMed Central

    Bramis, Ioannis; Triantopoulou, Charikleia; Madariaga, Juan; Dervenis, Christos

    2006-01-01

    Background. This article reviews the current results of radiofrequency application in the management of hepatocellular carcinoma (HCC) with reference to the comparison between the different surgical modalities. Method. An electronic search was performed for studies on the treatment of HCC. Results. Thermoablation by means of radiofrequency (RFA), microwave coagulation therapy (MCT) and laser-induced thermotherapy (LITT) provides tumor necrosis with a low complication rate. These methods are still not predictable and it is difficult to monitor the extent of necrosis in a real-time manner. Combined transarterial embolization and RF ablation is a promising strategy for large HCCs. Radiofrequency-assisted liver resection is unique and has become very popular recently because it permits parenchymal transection with minimal blood loss. Conclusion. Many alternative techniques have been applied recently for the management of HCC but their exact roles need to be defined by randomized studies. Advances in technology and refinements in technique may provide an effective and predictable way to ablate liver tumors using radiofrequency devices. PMID:18333136

  19. Process for selected gas oxide removal by radiofrequency catalysts

    DOEpatents

    Cha, C.Y.

    1993-09-21

    This process to remove gas oxides from flue gas utilizes adsorption on a char bed subsequently followed by radiofrequency catalysis enhancing such removal through selected reactions. Common gas oxides include SO[sub 2] and NO[sub x]. 1 figure.

  20. Longevity of radiofrequency identification device microchips in citrus trees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term identification of individual plants in the field is an important part of many types of botanical and horticultural research. In a previous report, we described methods for using implanted radiofrequency (RFID) microchips to tag citrus trees for field research. This report provides an upd...

  1. Optimization of the generator settings for endobiliary radiofrequency ablation

    PubMed Central

    Barret, Maximilien; Leblanc, Sarah; Vienne, Ariane; Rouquette, Alexandre; Beuvon, Frederic; Chaussade, Stanislas; Prat, Frederic

    2015-01-01

    AIM: To determine the optimal generator settings for endobiliary radiofrequency ablation. METHODS: Endobiliary radiofrequency ablation was performed in live swine on the ampulla of Vater, the common bile duct and in the hepatic parenchyma. Radiofrequency ablation time, “effect”, and power were allowed to vary. The animals were sacrificed two hours after the procedure. Histopathological assessment of the depth of the thermal lesions was performed. RESULTS: Twenty-five radiofrequency bursts were applied in three swine. In the ampulla of Vater (n = 3), necrosis of the duodenal wall was observed starting with an effect set at 8, power output set at 10 W, and a 30 s shot duration, whereas superficial mucosal damage of up to 350 μm in depth was recorded for an effect set at 8, power output set at 6 W and a 30 s shot duration. In the common bile duct (n = 4), a 1070 μm, safe and efficient ablation was obtained for an effect set at 8, a power output of 8 W, and an ablation time of 30 s. Within the hepatic parenchyma (n = 18), the depth of tissue damage varied from 1620 μm (effect = 8, power = 10 W, ablation time = 15 s) to 4480 μm (effect = 8, power = 8 W, ablation time = 90 s). CONCLUSION: The duration of the catheter application appeared to be the most important parameter influencing the depth of the thermal injury during endobiliary radiofrequency ablation. In healthy swine, the currently recommended settings of the generator may induce severe, supratherapeutic tissue damage in the biliary tree, especially in the high-risk area of the ampulla of Vater. PMID:26566429

  2. 47 CFR 80.83 - Protection from potentially hazardous RF radiation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... radiation. 80.83 Section 80.83 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Requirements-Ship Stations § 80.83 Protection from potentially hazardous RF radiation. Any license or renewal application for a ship earth station that will cause exposure to radiofrequency (RF) radiation in excess...

  3. 47 CFR 80.227 - Special requirements for protection from RF radiation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... radiation. 80.227 Section 80.227 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... requirements for protection from RF radiation. As part of the information provided with transmitters for ship... help prevent human exposure to radiofrequency (RF) radiation in excess of the RF exposure...

  4. 47 CFR 80.227 - Special requirements for protection from RF radiation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... radiation. 80.227 Section 80.227 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... requirements for protection from RF radiation. As part of the information provided with transmitters for ship... help prevent human exposure to radiofrequency (RF) radiation in excess of the RF exposure...

  5. 47 CFR 80.227 - Special requirements for protection from RF radiation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... radiation. 80.227 Section 80.227 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... requirements for protection from RF radiation. As part of the information provided with transmitters for ship... help prevent human exposure to radiofrequency (RF) radiation in excess of the RF exposure...

  6. 47 CFR 80.83 - Protection from potentially hazardous RF radiation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... radiation. 80.83 Section 80.83 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Requirements-Ship Stations § 80.83 Protection from potentially hazardous RF radiation. Any license or renewal application for a ship earth station that will cause exposure to radiofrequency (RF) radiation in excess...

  7. 47 CFR 80.227 - Special requirements for protection from RF radiation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... radiation. 80.227 Section 80.227 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... requirements for protection from RF radiation. As part of the information provided with transmitters for ship... help prevent human exposure to radiofrequency (RF) radiation in excess of the RF exposure...

  8. 47 CFR 80.83 - Protection from potentially hazardous RF radiation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... radiation. 80.83 Section 80.83 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Requirements-Ship Stations § 80.83 Protection from potentially hazardous RF radiation. Any license or renewal application for a ship earth station that will cause exposure to radiofrequency (RF) radiation in excess...

  9. 47 CFR 80.83 - Protection from potentially hazardous RF radiation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... radiation. 80.83 Section 80.83 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Requirements-Ship Stations § 80.83 Protection from potentially hazardous RF radiation. Any license or renewal application for a ship earth station that will cause exposure to radiofrequency (RF) radiation in excess...

  10. 47 CFR 80.83 - Protection from potentially hazardous RF radiation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... radiation. 80.83 Section 80.83 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Requirements-Ship Stations § 80.83 Protection from potentially hazardous RF radiation. Any license or renewal application for a ship earth station that will cause exposure to radiofrequency (RF) radiation in excess...

  11. 47 CFR 80.227 - Special requirements for protection from RF radiation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... radiation. 80.227 Section 80.227 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... requirements for protection from RF radiation. As part of the information provided with transmitters for ship... help prevent human exposure to radiofrequency (RF) radiation in excess of the RF exposure...

  12. Reduction of electronic noise from radiofrequency generator during radiofrequency ablation in interventional MRI.

    PubMed

    Oshiro, Thomas; Sinha, Usha; Lu, David; Sinha, Shantanu

    2002-01-01

    MRI has been used increasingly in the recent past for the guidance and monitoring of minimally invasive interventional procedures, using typically radiofrequency (RF) and laser energy, cryoablation, and percutaneous ethanol. RF energy has been used over the last 30 years for the ablation of tissues. Its use in conjunction with MRI for monitoring is limited, however, because of the electronic noise produced by the RF generators, which can significantly deteriorate image quality. The objective of this work was to devise methods by which this noise can be reduced to an acceptable level to allow simultaneous acquisition of MR images for monitoring purposes with the application of RF energy. Three different methods of noise reduction were investigated in a 0.2 T MR scanner: filtration using external hardware circuitry, MR scanner software-controlled filtration, and keyholing. The last two methods were unable by themselves to suppress the noise to an acceptable degree. Hardware filtration, however, provides excellent suppression of RF noise and is able to withstand up to 12 W of RF energy. When all the three approaches are combined, significant reduction of RF noise is achieved. The feasibility of creating an RF lesion of about 1.2 cm diameter in vivo in a porcine model simultaneously with temperature-sensitive MRI with adequate noise suppression is demonstrated. PMID:11884792

  13. Percutaneous radiofrequency ablation versus surgical radiofrequency ablation for malignant liver tumours: the long-term results

    PubMed Central

    Wong, John; Lee, Kit-Fai; Yu, Simon Chun-Ho; Lee, Paul Sing-Fun; Cheung, Yue-Sun; Chong, Ching-Ning; Ip, Philip Ching-Tak; Lai, Paul Bo-San

    2013-01-01

    Background Radiofrequency ablation (RFA) has been used to treat hepatocellular carcinoma (HCC) and liver metastases for more than 10 years with promising early outcomes. Preliminary results comparing percutaneous and surgical approaches have shown no difference in short-term outcomes. In this study, the longer-term outcomes were presented. Methods Patients with liver malignancies treated by RFA were prospectively studied from 2003 to 2011. Post-ablation assessment by computed tomography (CT) scan and serum biochemistry was performed at regular intervals. Recurrence rates and long-term survival were analysed. Results A total of 233 patients with liver malignancies (75.5% HCC and 24.5% liver metastases) were analysed. Three RFA approaches were used (percutaneous 58.4%, laparoscopic 9.4% and open 32.2%). The median follow-up time was 29 months. Complete ablation was achieved in 83.7%, with no difference between the two approaches. More wound and chest complications were observed in the surgical group. Intra-hepatic recurrences were observed in 69.5%; extra-hepatic recurrences were detected in 22.3%, with no difference between the two groups. There was no statistical difference between the two approaches in overall 1-, 3- and 5-year survival. Conclusion An extended period of follow-up in patients with liver malignancies showed that RFA is an effective treatment. No difference was demonstrated between the percutaneous and surgical approach, in terms of recurrence and survival. PMID:23458320

  14. Cryoballoon or Radiofrequency Ablation for Paroxysmal Atrial Fibrillation.

    PubMed

    Kuck, Karl-Heinz; Brugada, Josep; Fürnkranz, Alexander; Metzner, Andreas; Ouyang, Feifan; Chun, K R Julian; Elvan, Arif; Arentz, Thomas; Bestehorn, Kurt; Pocock, Stuart J; Albenque, Jean-Paul; Tondo, Claudio

    2016-06-01

    Background Current guidelines recommend pulmonary-vein isolation by means of catheter ablation as treatment for drug-refractory paroxysmal atrial fibrillation. Radiofrequency ablation is the most common method, and cryoballoon ablation is the second most frequently used technology. Methods We conducted a multicenter, randomized trial to determine whether cryoballoon ablation was noninferior to radiofrequency ablation in symptomatic patients with drug-refractory paroxysmal atrial fibrillation. The primary efficacy end point in a time-to-event analysis was the first documented clinical failure (recurrence of atrial fibrillation, occurrence of atrial flutter or atrial tachycardia, use of antiarrhythmic drugs, or repeat ablation) following a 90-day period after the index ablation. The noninferiority margin was prespecified as a hazard ratio of 1.43. The primary safety end point was a composite of death, cerebrovascular events, or serious treatment-related adverse events. Results A total of 762 patients underwent randomization (378 assigned to cryoballoon ablation and 384 assigned to radiofrequency ablation). The mean duration of follow-up was 1.5 years. The primary efficacy end point occurred in 138 patients in the cryoballoon group and in 143 in the radiofrequency group (1-year Kaplan-Meier event rate estimates, 34.6% and 35.9%, respectively; hazard ratio, 0.96; 95% confidence interval [CI], 0.76 to 1.22; P<0.001 for noninferiority). The primary safety end point occurred in 40 patients in the cryoballoon group and in 51 patients in the radiofrequency group (1-year Kaplan-Meier event rate estimates, 10.2% and 12.8%, respectively; hazard ratio, 0.78; 95% CI, 0.52 to 1.18; P=0.24). Conclusions In this randomized trial, cryoballoon ablation was noninferior to radiofrequency ablation with respect to efficacy for the treatment of patients with drug-refractory paroxysmal atrial fibrillation, and there was no significant difference between the two methods with regard to

  15. A radio-frequency sheath model for complex waveforms

    SciTech Connect

    Turner, M. M.; Chabert, P.

    2014-04-21

    Plasma sheaths driven by radio-frequency voltages occur in contexts ranging from plasma processing to magnetically confined fusion experiments. An analytical understanding of such sheaths is therefore important, both intrinsically and as an element in more elaborate theoretical structures. Radio-frequency sheaths are commonly excited by highly anharmonic waveforms, but no analytical model exists for this general case. We present a mathematically simple sheath model that is in good agreement with earlier models for single frequency excitation, yet can be solved for arbitrary excitation waveforms. As examples, we discuss dual-frequency and pulse-like waveforms. The model employs the ansatz that the time-averaged electron density is a constant fraction of the ion density. In the cases we discuss, the error introduced by this approximation is small, and in general it can be quantified through an internal consistency condition of the model. This simple and accurate model is likely to have wide application.

  16. Radiofrequency thermoneurolysis for the treatment of Morton's neuroma.

    PubMed

    Moore, Joshua L; Rosen, Ritchard; Cohen, Jeffrey; Rosen, Brad

    2012-01-01

    Pedal neuroma is a common disorder. The authors undertook a review of 32 feet in 29 patients with a symptomatic neuroma treated between January 2007 and January 2010 to evaluate the effectiveness of radiofrequency thermoneurolysis therapy in alleviating symptoms. Overall relief of symptoms was rated as complete by 24 (83%) patients, with 5 patients experiencing minimal to no relief. Two patients were lost to follow-up after 1 month, 2 patients opted for no further intervention, and 1 patient went to open resection of the neuroma. Average follow-up was 13 months and total recovery time was 2 days. Complications included 1 foot with cellulitis treated by a course of oral antibiotics. The results of this retrospective study indicate radiofrequency thermoneurolysis therapy is a safe, effective, and minimally invasive alternative treatment for symptomatic neuromas of the foot. PMID:22055491

  17. [Percutaneous ablation of renal tumors: radiofrequency ablation or cryoablation?].

    PubMed

    Buy, X; Lang, H; Garnon, J; Gangi, A

    2011-09-01

    Percutaneous ablation of renal tumors, including radiofrequency ablation and cryoablation, are increasingly being used for small tumors as an alternative to surgery for poor surgical candidates. Compared to radiofrequency ablation, cryoablation has several advantages: improved volume control and preservation of adjacent structures due to the excellent depiction of the ice ball on CT and MRI; better protection of the collecting system for central tumor with reduced risk of postprocedural urinary fistula. The main pitfall of cryoablation is the higher cost. Therefore, cryoablation should be reserved for the treatment of complex tumors. In this article, we will review the different steps of percutaneous renal tumor ablation procedures including patient selection, technical considerations, and follow-up imaging. PMID:21944236

  18. Novel catheter enabling simultaneous radiofrequency ablation and optical coherence reflectometry

    PubMed Central

    Herranz, D.; Lloret, Juan; Jiménez-Valero, Santiago; Rubio-Guivernau, J. L.; Margallo-Balbás, Eduardo

    2015-01-01

    A novel radiofrequency ablation catheter has been developed with integrated custom designed optics, enabling real-time monitoring of radiofrequency ablation procedures through polarization-sensitive optical coherence reflectometry. The optics allow for proper tissue illumination through a view-port machined in the catheter tip, thus providing lesion depth control over the RF ablation treatment. The system was verified in an in-vitro model of swine myocardium. Optical performance and thermal stability was confirmed after more than 25 procedures, without any damage to the optical assembly induced by thermal stress or material degradation. The use of this catheter in RF ablation treatments may make possible to assess lesion depth during therapy, thus translating into a reduction of potential complications on the procedure. PMID:26417499

  19. Irrigated Tip Catheters for Radiofrequency Ablation in Ventricular Tachycardia

    PubMed Central

    Grothoff, Matthias; Dinov, Borislav; Kosiuk, Jedrzej; Richter, Sergio; Sommer, Philipp; Breithardt, Ole A.; Bollmann, Andreas; Arya, Arash; Hindricks, Gerhard

    2015-01-01

    Radiofrequency (RF) ablation with irrigated tip catheters decreases the likelihood of thrombus and char formation and enables the creation of larger lesions. Due to the potential dramatic consequences, the prevention of thromboembolic events is of particular importance for left-sided procedures. Although acute success rates of ventricular tachycardia (VT) ablation are satisfactory, recurrence rate is high. Apart from the progress of the underlying disease, reconduction and the lack of effective transmural lesions play a major role for VT recurrences. This paper reviews principles of lesion formation with radiofrequency and the effect of tip irrigation as well as recent advances in new technology. Potential areas of further development of catheter technology might be the improvement of mapping by better substrate definition and resolution, the introduction of bipolar and multipolar ablation techniques into clinical routine, and the use of alternative sources of energy. PMID:25705659

  20. Irrigated tip catheters for radiofrequency ablation in ventricular tachycardia.

    PubMed

    Müssigbrodt, Andreas; Grothoff, Matthias; Dinov, Borislav; Kosiuk, Jedrzej; Richter, Sergio; Sommer, Philipp; Breithardt, Ole A; Rolf, Sascha; Bollmann, Andreas; Arya, Arash; Hindricks, Gerhard

    2015-01-01

    Radiofrequency (RF) ablation with irrigated tip catheters decreases the likelihood of thrombus and char formation and enables the creation of larger lesions. Due to the potential dramatic consequences, the prevention of thromboembolic events is of particular importance for left-sided procedures. Although acute success rates of ventricular tachycardia (VT) ablation are satisfactory, recurrence rate is high. Apart from the progress of the underlying disease, reconduction and the lack of effective transmural lesions play a major role for VT recurrences. This paper reviews principles of lesion formation with radiofrequency and the effect of tip irrigation as well as recent advances in new technology. Potential areas of further development of catheter technology might be the improvement of mapping by better substrate definition and resolution, the introduction of bipolar and multipolar ablation techniques into clinical routine, and the use of alternative sources of energy. PMID:25705659

  1. Comb-based radiofrequency photonic filters with rapid tunability and high selectivity

    NASA Astrophysics Data System (ADS)

    Supradeepa, V. R.; Long, Christopher M.; Wu, Rui; Ferdous, Fahmida; Hamidi, Ehsan; Leaird, Daniel E.; Weiner, Andrew M.

    2012-03-01

    Photonic technologies have received considerable attention regarding the enhancement of radiofrequency electrical systems, including high-frequency analogue signal transmission, control of phased arrays, analog-to-digital conversion and signal processing. Although the potential of radiofrequency photonics for the implementation of tunable electrical filters over broad radiofrequency bandwidths has been much discussed, the realization of programmable filters with highly selective filter lineshapes and rapid reconfigurability has faced significant challenges. A new approach for radiofrequency photonic filters based on frequency combs offers a potential route to simultaneous high stopband attenuation, fast tunability and bandwidth reconfiguration. In one configuration, tuning of the radiofrequency passband frequency is demonstrated with unprecedented (~40 ns) speed by controlling the optical delay between combs. In a second, fixed filter configuration, cascaded four-wave mixing simultaneously broadens and smoothes the comb spectra, resulting in Gaussian radiofrequency filter lineshapes exhibiting an extremely high (>60 dB) main lobe to sidelobe suppression ratio and (>70 dB) stopband attenuation.

  2. Diaphragmatic Hernia After Radiofrequency Ablation for Hepatocellular Carcinoma

    SciTech Connect

    Yamagami, Takuji Yoshimatsu, Rika; Matsushima, Shigenori; Tanaka, Osamu; Miura, Hiroshi; Nishimura, Tsunehiko

    2011-02-15

    We describe a 71-year-old woman with a hepatocellular carcinoma who underwent percutaneous radiofrequency ablation (RF) with a single internally cooled electrode under computed tomography (CT) fluoroscopic guidance. Nine months after the procedure, CT images showed herniation of the large intestine into the right pleural cavity. To our knowledge this complication of RF performed with a single internally cooled electrode under CT guidance has not been previously reported.

  3. Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

    PubMed Central

    Lee, Jeong Hyun; Valcavi, Roberto; Pacella, Claudio M.; Rhim, Hyunchul; Na, Dong Gyu

    2011-01-01

    Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation. PMID:21927553

  4. Computer simulations of ions in radio-frequency traps

    NASA Technical Reports Server (NTRS)

    Williams, A.; Prestage, J. D.; Maleki, L.; Djomehri, J.; Harabetian, E.

    1990-01-01

    The motion of ions in a trapped-ion frequency standard affects the stability of the standard. In order to study the motion and structures of large ion clouds in a radio-frequency (RF) trap, a computer simulation of the system that incorporates the effect of thermal excitation of the ions was developed. Results are presented from the simulation for cloud sizes up to 512 ions, emphasizing cloud structures in the low-temperature regime.

  5. Four-Sector Cylindrical Radio-Frequency Ion Trap

    NASA Technical Reports Server (NTRS)

    Melbourne, Ruthann K.; Prestage, John D.; Maleki, Lutfollah

    1992-01-01

    Proposed linear radio-frequency ion trap consists of closed metal cylinder partitioned into four equal cylindrical-sector electrodes and two circular end electrodes. Features include relatively large ion-storage capacity and shielding against external fields. Used in frequency-standard laboratories to confine 199Hg+ ions electrodynamically in isolation from external environment. Similar to device described in "Linear Ion Trap for Atomic Clock" (NPO-17758).

  6. Perforated-Layer Implementation Of Radio-Frequency Lenses

    NASA Technical Reports Server (NTRS)

    Dolgin, Benjamin P.

    1996-01-01

    Luneberg-type radio-frequency dielectric lenses made of stacked perforated circular dielectric sheets, according to proposal. Perforation pattern designed to achieve required spatial variation of permittivity. Consists of round holes distributed across face of each sheet in "Swiss-cheese" pattern, plus straight or curved slots that break up outer parts into petals in "daisy-wheel" pattern. Holes and slots made by numerically controlled machining.

  7. Radiofrequency electron swarm transport in reactive gases and plasmas

    NASA Astrophysics Data System (ADS)

    Maeda, K.; Makabe, T.

    1994-01-01

    This paper gives a historical review of the development of radiofrequency (RF) electron swarm from a theoretical point of view. Also the recent progress of the direct numerical procedure (DNP) for solving the Boltzmann equation will be discussed with some typical examples of the temporally modulated velocity distribution in Ar and HCl in an RF field. The significance of DNP will be demonstrated for an RF swarm in the frequency range from MHz to GHz at strong fields.

  8. Effective bone hemostasis and healing using radiofrequency and conductive fluid.

    PubMed

    Bertone, Alicia; Lipson, David; Kamei, Janet; Litsky, Alan; Weisbrode, Stephen

    2006-05-01

    Hemostasis in bone is difficult to achieve because of the mineral content. Current techniques often are ineffective, can have systemic effects, or leave residual material in the wound. Our hypotheses were that a wand device coupling radiofrequency energy with a cooling conductive saline solution, applied topically to bone, could produce superior hemostasis compared with conventional electrocautery or no treatment, and not impede bone healing. Immediate hemostasis and subsequent bone healing for 6 and 12 weeks were evaluated in an iliac crest ostectomy (cancellous bone) and a drilled tibia defect (cortical bone) sheep model. Outcome variables were amount and intensity of bleeding, serial radiography, quantitative computed tomography, histology and mechanical testing. Control of bleeding was nearly complete (93%) and greater with the radiofrequency/saline treatment compared with electrocautery (56%) or no treatment (0%) in cancellous bone and cortical bone. Electrocautery induced surface char (black carbon debris) that could be seen at 6 and 12 weeks. There were no differences in bone healing between the radiofrequency and electrocautery device applications or untreated bone. At 12 weeks, all healing tibiae defects were as strong as undrilled tibiae. This may be an effective method to produce rapid hemostasis in bone without char or healing complications. PMID:16467618

  9. [Treatment of atrial fibrillation using maze procedure by radiofrequency ablation].

    PubMed

    Cai, Z; Sun, G; Du, R

    1997-12-01

    From May 1994 to May 1996, 20 cases of atrial fibrillation were treated by means of Maze procedure by radiofrequenncy ablation, at the same time 19 cases of these patients were complicated with rheumatic heart valve disease and valve replacement operations were perfomned, in the other case atrial septal defect was repaired. Yoshio Kosakai's operation route was adopted in radiofrequency ablation procedure. After operation 16 patients of atrial fibrillation resumed sinus rhythm (80%), in 4 casess of atrial fibrillation sinus rhythm was unsuccessfully restored, two patients remained atrial fibrillation, one patient was of atrial flutter, the other was of nodal rhythm. Short time was needed in radiofrequency ablation Maze procedure, average time increase of aortic clamping was 20.5 minutes, and there was no danger of hemorrhage related to this kinds of Maze procedure. During 7-10 days after operation, there appeared superventricular arrhythmia which might be related to ill-distribution of radiofrequency ablation, and interference of atrial electric activity. PMID:10677989

  10. Radiofrequency catheter ablation of accessory pathways in infants.

    PubMed Central

    Benito, F.; Sánchez, C.

    1997-01-01

    OBJECTIVE: To evaluate the indications, results and complications of radiofrequency catheter ablation in small infants with supraventricular tachycardia due to an accessory atrioventricular pathway. METHODS: Five infants less than 9 months old underwent radiofrequency catheter ablation of accessory pathways. Ablation was done for medically refractory tachyarrhythmia associated with aborted sudden death in two patients, left ventricular dysfunction in one, failure of antiarrhythmic drugs in one, and planned cardiac surgery in one. All five patients underwent a single successful procedure. Three left free wall pathways were ablated by transseptal approach, a right posteroseptal pathway was ablated from the inferior vena cava, and a left posteroseptal pathway was approached from the inferior vena cava into the coronary sinus. A deflectable 5F bipolar electrode catheter with a 3 mm tip was used. RESULTS: A sudden increment in impedance indicative of coagulum formation was observed in two procedures. One patient developed a transient ischaemic complication after ablation of a left lateral accessory pathway by transseptal approach. This patient had mild pericardial effusion after the procedure. Moderate pericardial effusion was also noted in another patient. After a mean follow up of 18.4 months all patients are symptom free without treatment. CONCLUSIONS: Radiofrequency catheter ablation can be performed successfully in infants. Temperature monitoring in 5F ablation catheters would be desirable to prevent the development of coagulum. Echocardiography must be performed after the ablation procedure to investigate pericardial effusion. Images PMID:9326990

  11. [Radiofrequency ablation of accessory pathways in pre-excitation syndrome].

    PubMed

    Pfeiffer, D; Tebbenjohanns, J; Jung, W; Manz, M; Lüderitz, B

    1993-04-16

    Various parameters relating to the radio-frequency ablation of accessory pathways were studied in 53 patients (27 males, 26 females: mean age 38.5 [14-64] years) with a history of paroxysmal tachycardia (over 1 month to 50 years), shown to be caused by an accessory pathway (Wolff-Parkinson-White syndrome). In all patients the following values were obtained: (1) number of procedures necessary to achieve permanent blockage of the accessory pathway (1-4); (2) duration of each procedure (45-420 min); (3) duration of fluoroscopy (5-102 min); (4) number of necessary radio-frequency applications (1-48); and (5) cumulative energy per procedure. To ablate left-lateral pathways (n = 10) required fewer procedures, shorter duration per procedure, shorter fluoroscopy time, fewer current applications and less total energy than coagulation of right-sided pathways (n = 10). Those various parameters were greatest for ablation of septal and para-septal pathways (n = 9). Pathways which conducted only retrogradely (n = 15) were more difficult to ablate than those with anterograde conduction (n = 38). There were two complications. In one case a tension pneumothorax occurred after faulty puncture of the subclavian vein; in the other, the left ventricle was perforated causing an acute tamponade which required pericardiocentesis with subsequent suture closure of the perforation. It is concluded that, in principle, all accessory pathways, regardless of their conduction potential and site, can be ablated by a radio-frequency current. PMID:8472633

  12. Survey of ambient electromagnetic and radio-frequency interference levels in nuclear power plants

    SciTech Connect

    Kercel, S.W.; Moore, M.R.; Blakeman, E.D.; Ewing, P.D.; Wood, R.T.

    1996-11-01

    This document reports the results of a survey of ambient electromagnetic conditions in representative nuclear power plants. The U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research engaged the Oak Ridge National Laboratory (ORNL) to perform these measurements to characterize the electromagnetic interference (EMI) and radio-frequency interference (RFI) levels that can be expected in nuclear power plant environments. This survey is the first of its kind, being based on long-term unattended observations. The data presented in this report were measured at eight different nuclear units and required 14 months to collect. A representative sampling of power plant conditions (reactor type, operating mode, site location) monitored over extended observation periods (up to 5 weeks) were selected to more completely determine the characteristic electromagnetic environment for nuclear power plants. Radiated electric fields were measured over the frequency range of 5 MHz to 8 GHz. Radiated magnetic fields and conducted EMI events were measured over the frequency range of 305 Hz to 5 MHz. Highest strength observations of the electromagnetic ambient environment across all measurement conditions at each site provide frequency-dependent profiles for EMI/RFI levels in nuclear power plants.

  13. A Simulation Study of a Radiofrequency Localization System for Tracking Patient Motion in Radiotherapy.

    PubMed

    Ostyn, Mark; Kim, Siyong; Yeo, Woon-Hong

    2016-01-01

    One of the most widely used tools in cancer treatment is external beam radiotherapy. However, the major risk involved in radiotherapy is excess radiation dose to healthy tissue, exacerbated by patient motion. Here, we present a simulation study of a potential radiofrequency (RF) localization system designed to track intrafraction motion (target motion during the radiation treatment). This system includes skin-wearable RF beacons and an external tracking system. We develop an analytical model for direction of arrival measurement with radio frequencies (GHz range) for use in a localization estimate. We use a Monte Carlo simulation to investigate the relationship between a localization estimate and angular resolution of sensors (signal receivers) in a simulated room. The results indicate that the external sensor needs an angular resolution of about 0.03 degrees to achieve millimeter-level localization accuracy in a treatment room. This fundamental study of a novel RF localization system offers the groundwork to design a radiotherapy-compatible patient positioning system for active motion compensation. PMID:27089342

  14. Radio-frequency sheath voltages and slow wave electric field spatial structure

    SciTech Connect

    Colas, Laurent Lu, Ling-Feng; Křivská, Alena; Jacquot, Jonathan

    2015-12-10

    We investigate theoretically how sheath radio-frequency (RF) oscillations relate to the spatial structure of the RF parallel electric field emitted by Ion Cyclotron (IC) wave launchers, using a simple model of Slow Wave (SW) evanescence coupled with Direct Current (DC) plasma biasing via sheath boundary conditions in a plasma-filled 2-dimensional (parallel, radial) rectangle. Within a “wide sheaths” asymptotic regime, valid for large-amplitude near RF fields, our model becomes partly linear: the sheath oscillating voltage at open field line boundaries is a linear combination of elementary contributions by every source point of the radiated RF field map. These individual contributions are all the more intense as the SW emission point is toroidally nearer to the sheath walls. A limit formula is given for a source infinitely close to the sheaths. The decay of sheath RF voltages with the sheath/source parallel distance is quantified as a function of two characteristic SW evanescence lengths. Decay lengths are smaller than antenna parallel extensions. The sheath RF voltages at an IC antenna side limiter are therefore mainly sensitive to SW emission near this limiter, as recent observations suggest. Toroidal proximity effects could also explain why sheath oscillations persist with antisymmetric strap toroidal phasing, despite the parallel anti-symmetry of the radiated field map. They could also justify current attempts at reducing the RF fields induced near antenna boxes to attenuate sheath oscillations in their vicinity.

  15. A Simulation Study of a Radiofrequency Localization System for Tracking Patient Motion in Radiotherapy

    PubMed Central

    Ostyn, Mark; Kim, Siyong; Yeo, Woon-Hong

    2016-01-01

    One of the most widely used tools in cancer treatment is external beam radiotherapy. However, the major risk involved in radiotherapy is excess radiation dose to healthy tissue, exacerbated by patient motion. Here, we present a simulation study of a potential radiofrequency (RF) localization system designed to track intrafraction motion (target motion during the radiation treatment). This system includes skin-wearable RF beacons and an external tracking system. We develop an analytical model for direction of arrival measurement with radio frequencies (GHz range) for use in a localization estimate. We use a Monte Carlo simulation to investigate the relationship between a localization estimate and angular resolution of sensors (signal receivers) in a simulated room. The results indicate that the external sensor needs an angular resolution of about 0.03 degrees to achieve millimeter-level localization accuracy in a treatment room. This fundamental study of a novel RF localization system offers the groundwork to design a radiotherapy-compatible patient positioning system for active motion compensation. PMID:27089342

  16. Radiofrequency Ablation Treatment in Proximity to the Gallbladder Without Subsequent Acute Cholecystitis

    SciTech Connect

    Patti, Jay W.; Neeman, Ziv Wood, Bradford J.

    2003-08-15

    Initial reports have suggested that proximity of liver tumors to the gallbladder may increase the risk for cholecystitis after radiofrequency ablation. A colon adenocarcinoma metastasis to the liver in contact with the gallbladder was successfully treated with radiofrequency ablation without subsequent cholecystitis.

  17. Radiofrequency for the Treatment of Lumbar Radicular Pain: Impact on Surgical Indications

    PubMed Central

    Trinidad, José Manuel; Carnota, Ana Isabel; Failde, Inmaculada; Torres, Luis Miguel

    2015-01-01

    Study Design. Quasiexperimental study. Objective. To investigate whether radiofrequency treatment can preclude the need for spinal surgery in both the short term and long term. Background. Radiofrequency is commonly used to treat lumbosacral radicular pain. Only few studies have evaluated its effects on surgical indications. Methods. We conducted a quasiexperimental study of 43 patients who had been scheduled for spinal surgery. Radiofrequency was indicated for 25 patients. The primary endpoint was the decision of the patient to reject spinal surgery 1 month and 1 year after treatment (pulsed radiofrequency of dorsal root ganglion, 76%; conventional radiofrequency of the medial branch, 12%; combined technique, 12%). The primary endpoint was the decision of the patient to reject spinal surgery 1 month and 1 year after treatment. In addition, we also evaluated adverse effects, ODI, NRS. Results. We observed after treatment with radiofrequency 80% of patients rejected spinal surgery in the short term and 76% in the long term. We conclude that radiofrequency is a useful treatment strategy that can achieve very similar outcomes to spinal surgery. Patients also reported a very high level of satisfaction (84% satisfied/very satisfied). We also found that optimization of the electrical parameters of the radiofrequency improved the outcome of this technique. PMID:26351581

  18. Sampling modulation technique in radio-frequency helium glow discharge emission source by use of pulsed laser ablation.

    PubMed

    Naeem, Tariq Mahmood; Matsuta, Hideyuki; Wagatsuma, Kazuaki

    2004-05-01

    An emission excitation source comprising a high-frequency diode-pumped Q-switched Nd:YAG laser and a radio-frequency powered glow discharge lamp is proposed. In this system sample atoms ablated by the laser irradiation are introduced into the lamp chamber and subsequently excited by the helium glow discharge plasma. The pulsed operation of the laser can produce a cyclic variation in the emission intensities of the sample atoms whereas the plasma gas species emit the radiation continuously. The salient feature of the proposed technique is the selective detection of the laser modulation signal from the rest of the continuous background emissions, which can be achieved with the phase sensitive detection of the lock-in amplifier. The arrangement may be used to estimate the emission intensity of the laser ablated atom, free from the interference of other species present in the plasma. The experiments were conducted with a 13.56 MHz radio-frequency (rf) generator operated at 80 W power to produce plasma and the laser at a wavelength of 1064 nm (pulse duration:34 ns, repetition rate:7 kHz and average pulse energy of about 0.36 mJ) was employed for sample ablation. The measurements resulted in almost complete removal of nitrogen molecular bands (N(2)(+) 391.44 nm). Considerable reduction (about 75%) in the emission intensity of a carbon atomic line (C I 193.03 nm) was also observed. PMID:15034707

  19. Multiplexing of Radio-Frequency Single Electron Transistors

    NASA Technical Reports Server (NTRS)

    Stevenson, Thomas R.; Pellerano, F. A.; Stahle, C. M.; Aidala, K.; Schoelkopf, R. J.; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    We present results on wavelength division multiplexing of radio-frequency single electron transistors. We use a network of resonant impedance matching circuits to direct applied rf carrier waves to different transistors depending on carrier frequency. A two-channel demonstration of this concept using discrete components successfully reconstructed input signals with small levels of cross coupling. A lithographic version of the rf circuits had measured parameters in agreement with electromagnetic modeling, with reduced cross capacitance and inductance, and should allow 20 to 50 channels to be multiplexed.

  20. Time-domain simulation of nonlinear radiofrequency phenomena

    SciTech Connect

    Jenkins, Thomas G.; Austin, Travis M.; Smithe, David N.; Loverich, John; Hakim, Ammar H.

    2013-01-15

    Nonlinear effects associated with the physics of radiofrequency wave propagation through a plasma are investigated numerically in the time domain, using both fluid and particle-in-cell (PIC) methods. We find favorable comparisons between parametric decay instability scenarios observed on the Alcator C-MOD experiment [J. C. Rost, M. Porkolab, and R. L. Boivin, Phys. Plasmas 9, 1262 (2002)] and PIC models. The capability of fluid models to capture important nonlinear effects characteristic of wave-plasma interaction (frequency doubling, cyclotron resonant absorption) is also demonstrated.

  1. TOPICAL REVIEW: Radio-frequency amplifiers based on dc SQUIDs

    NASA Astrophysics Data System (ADS)

    Mück, Michael; McDermott, Robert

    2010-09-01

    SQUIDs are an attractive candidate for the amplification of low-level rf and microwave signals. Compared to semiconductor amplifiers, they offer lower noise and much lower power dissipation. Especially at frequencies below 1 GHz, the improvement in noise temperature compared to the best cold semiconductor amplifiers can be as high as 50; noise temperatures only slightly above the quantum limit have been achieved in this frequency range. This article will review the current status of radio-frequency amplifiers based on dc SQUIDs and provide detailed discussions of amplifier noise temperature, input and output impedance, and nonlinearities.

  2. Radiofrequency Ablation of Thyroid Nodules: Basic Principles and Clinical Application

    PubMed Central

    Shin, Ji Hoon; Baek, Jung Hwan; Ha, Eun Ju; Lee, Jeong Hyun

    2012-01-01

    Radiofrequency (RF) ablation has been gaining popularity as a minimally invasive treatment for benign thyroid nodules regardless of the extent of the solid component. RF ablation of benign nodules demonstrated volume reductions of 33–58% after one month and 51–85% after six months, while solving nodule-related clinical problems. RF ablation has recently shown positive short-term results for locoregional control as well as symptom improvement in patients with recurrent thyroid cancers. This paper reviews the basic physics, indications, patient preparation, devices, procedures, clinical results, and complications of RF ablation. PMID:23133449

  3. Eddy current imaging with an atomic radio-frequency magnetometer

    NASA Astrophysics Data System (ADS)

    Wickenbrock, Arne; Leefer, Nathan; Blanchard, John W.; Budker, Dmitry

    2016-05-01

    We use a radio-frequency 85Rb alkali-vapor cell magnetometer based on a paraffin-coated cell with long spin-coherence time and a small, low-inductance driving coil to create highly resolved conductivity maps of different objects. We resolve sub-mm features in conductive objects, we characterize the frequency response of our technique, and by operating at frequencies up to 250 kHz we are able to discriminate between differently conductive materials based on the induced response. The method is suited to cover a wide range of driving frequencies and can potentially be used for detecting non-metallic objects with low DC conductivity.

  4. Electromagnetic induction imaging with a radio-frequency atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Deans, Cameron; Marmugi, Luca; Hussain, Sarah; Renzoni, Ferruccio

    2016-03-01

    We report on a compact, tunable, and scalable to large arrays imaging device, based on a radio-frequency optically pumped atomic magnetometer operating in magnetic induction tomography modality. Imaging of conductive objects is performed at room temperature, in an unshielded environment and without background subtraction. Conductivity maps of target objects exhibit not only excellent performance in terms of shape reconstruction but also demonstrate detection of sub-millimetric cracks and penetration of conductive barriers. The results presented here demonstrate the potential of a future generation of imaging instruments, which combine magnetic induction tomography and the unmatched performance of atomic magnetometers.

  5. Characterization of superconducting radiofrequency breakdown by two-mode excitation

    SciTech Connect

    Eremeev, Grigory V.; Palczewski, Ari D.

    2014-01-14

    We show that thermal and magnetic contributions to the breakdown of superconductivity in radiofrequency (RF) fields can be separated by applying two RF modes simultaneously to a superconducting surface. We develop a simple model that illustrates how mode-mixing RF data can be related to properties of the superconductor. Within our model the data can be described by a single parameter, which can be derived either from RF or thermometry data. Our RF and thermometry data are in good agreement with the model. We propose to use mode-mixing technique to decouple thermal and magnetic effects on RF breakdown of superconductors.

  6. Subsurface Laser and Radiofrequency for Face and Body Rejuvenation.

    PubMed

    DiBernardo, Barry E; DiBernardo, Gabriella; Pozner, Jason N

    2016-07-01

    Minimally invasive devices are a departure from standard laser therapies, because energy is delivered directly below the skin through a 1-mm incision. Lasers can affect such tissues as fat for enhanced disruption, coagulation of small blood vessels, and skin tightening at the right temperatures. Minimally invasive radiofrequency devices can tighten skin but can also improve neck muscle laxity. These devices can achieve results not possible with traditional external devices and, because the skin is not penetrated with energy, a much improved healing profile is seen as well. PMID:27363766

  7. Percutaneous radiofrequency ablation of primary intraosseous spinal glomus tumor.

    PubMed

    Becce, Fabio; Richarme, Delphine; Letovanec, Igor; Gilgien, Willy; Theumann, Nicolas

    2012-04-01

    The glomus tumor is a rare, benign, but painful vascular neoplasm arising from the neuromyoarterial glomus. Primary intraosseous glomus tumor is even rarer, with only about 20 cases reported in the literature so far, 5 of which involved the spine. Surgical resection is currently considered the treatment of choice. We herewith present an uncommon case of primary intraosseous spinal glomus tumor involving the right pedicle of the eleventh thoracic vertebra (T11). To our knowledge, this is the first case of primary intraosseous spinal glomus tumor successfully treated by percutaneous CT-guided radiofrequency ablation (RFA). PMID:22072240

  8. A Complicated Postsurgical Echinococcal Cyst Treated with Radiofrequency Ablation

    SciTech Connect

    Thanos, L. Mylona, S.; Brontzakis, P.; Ptohis, N.; Karaliotas, K.

    2008-01-15

    Surgery of hydatid cysts is often complicated with intrabiliary rupture (IBR), which if not recognized may lead to biliary fistula with rather high rates of morbidity and mortality. We report our experience with the application of radiofrequency (RF) ablation for the treatment of an operated hepatic echinococcal cyst which was complicated with biliocystic communication and cysteocutaneous fistula with bile leakage. RF ablation was performed under CT guidance into the remaining cyst through the cutaneous fistula. Since ablation of the cyst and the fistula the patient has been asymptomatic.

  9. Method and apparatus for cartilage reshaping by radiofrequency heating

    DOEpatents

    Wong, Brian J.; Milner, Thomas E.; Sobol, Emil N.; Keefe, Michael W.

    2003-07-08

    A method and apparatus for reshaping cartilage using radiofrequency heating. The cartilage temperature is raised sufficiently for stress relaxation to occur in the cartilage, but low enough so that significant denaturation of the cartilage does not occur. The RF electrodes may be designed to also function as molds, preses, clamps, or mandrills to deform the cartilage tissue. Changes in various properties of the cartilage associated with stress relaxation in the cartilage may be measured in order to provide the control signal to provide effective reshaping without denaturation.

  10. [Clinical monitoring in areas of exposure to radiofrequency electromagnetic fields].

    PubMed

    Suvorov, I M

    2013-01-01

    Clinical syndromes induced by high intensity radiofrequency electromagnetic field chronic exposure are described. Persons injured by occupational exposure have been observed central nervous system changes in diencephalic syndrome form, cardio-vascular system changes revealed in atherosclerosis, isch(a)emic heart disease and coronary insufficiency rapid progressive expansion. General public living in territory of radar station exposure zone different functional disorders have been identified: vegetative dystonia (asthenovegetative syndrome), thrombocytopenia, decrease of blood coagulation index, and thyroid gland function changes. Observed diseases clinical variability may be determined by electromagnetic exposure characteristics. PMID:23785812

  11. REWARMING MICE FROM HYPOTHERMIA BY EXPOSURE TO 2450-MHZ MICROWAVE RADIATION

    EPA Science Inventory

    Radiofrequency (RF) radiation between frequencies of 1 MHz and 100 GHz is, to varying degrees, readily transmitted and absorbed in biological tissues. Because of its internal absorption characteristics, RF radiation in the microwave spectrum (300-10,000 MHz) has been used in case...

  12. Use of a vascular sheath for introduction of radiofrequency ablation probe during radiofrequency ablation of osteoid osteoma

    PubMed Central

    Ahmed, Munawwar; Keshava, Shyamkumar N; Moses, Vinu; Mammen, Suraj; Jacob, Korula Mani; Madhuri, Vrisha

    2015-01-01

    Radiofrequency ablation (RFA) has now become a preferred treatment option for osteoid osteoma. Accurate placement of RFA probe into the nidus of osteoid osteoma is important for good clinical outcome. Various methods and techniques have been described in the literature available. We describe the technique of using a vascular access sheath for introduction of RFA probe after bone drilling, which prevents loss of access to drill track and also serves as a pathway for accurate placement of RFA probe, thereby reducing the risk of damage to the RFA probe tip itself and the surrounding soft tissue. PMID:26752816

  13. Probing the fundamental limit of niobium in high radiofrequency fields by dual mode excitation in superconducting radiofrequency cavities

    SciTech Connect

    Eremeev, Grigory; Geng, Rongli; Palczewski, Ari

    2011-07-01

    We have studied thermal breakdown in several multicell superconducting radiofrequency cavity by simultaneous excitation of two TM{sub 010} passband modes. Unlike measurements done in the past, which indicated a clear thermal nature of the breakdown, our measurements present a more complex picture with interplay of both thermal and magnetic effects. JLab LG-1 that we studied was limited at 40.5 MV/m, corresponding to B{sub peak} = 173 mT, in 8{pi}/9 mode. Dual mode measurements on this quench indicate that this quench is not purely magnetic, and so we conclude that this field is not the fundamental limit in SRF cavities.

  14. Osteoid Osteoma: Experience with Laser- and Radiofrequency-Induced Ablation

    SciTech Connect

    Gebauer, Bernhard Tunn, Per-Ulf; Gaffke, Gunnar; Melcher, Ingo; Felix, Roland; Stroszczynski, Christian

    2006-04-15

    The purpose of this study was to analyze the clinical outcome of osteoid osteoma treated by thermal ablation after drill opening. A total of 17 patients and 20 procedures were included. All patients had typical clinical features (age, pain) and a typical radiograph showing a nidus. In 5 cases, additional histological specimens were acquired. After drill opening of the osteoid osteoma nidus, 12 thermal ablations were induced by laser interstitial thermal therapy (LITT) (9F Power-Laser-Set; Somatex, Germany) and 8 ablations by radiofrequency ablation (RFA) (RITA; StarBurst, USA). Initial clinical success with pain relief has been achieved in all patients after the first ablation. Three patients had an osteoid osteoma recurrence after 3, 9, and 10 months and were successfully re-treated by thermal ablation. No major complication and one minor complication (sensible defect) were recorded. Thermal ablation is a safe and minimally invasive therapy option for osteoid osteoma. Although the groups are too small for a comparative analysis, we determined no difference between laser- and radiofrequency-induced ablation in clinical outcome after ablation.

  15. Mathematical Modeling of Radiofrequency Ablation for Varicose Veins

    PubMed Central

    Choi, Sun Young; Kwak, Byung Kook

    2014-01-01

    We present a three-dimensional mathematical model for the study of radiofrequency ablation (RFA) with blood flow for varicose vein. The model designed to analyze temperature distribution heated by radiofrequency energy and cooled by blood flow includes a cylindrically symmetric blood vessel with a homogeneous vein wall. The simulated blood velocity conditions are U = 0, 1, 2.5, 5, 10, 20, and 40 mm/s. The lower the blood velocity, the higher the temperature in the vein wall and the greater the tissue damage. The region that is influenced by temperature in the case of the stagnant flow occupies approximately 28.5% of the whole geometry, while the region that is influenced by temperature in the case of continuously moving electrode against the flow direction is about 50%. The generated RF energy induces a temperature rise of the blood in the lumen and leads to an occlusion of the blood vessel. The result of the study demonstrated that higher blood velocity led to smaller thermal region and lower ablation efficiency. Since the peak temperature along the venous wall depends on the blood velocity and pullback velocity, the temperature distribution in the model influences ablation efficiency. The vein wall absorbs more energy in the low pullback velocity than in the high one. PMID:25587351

  16. Catheter ablation of atrioventricular accessory pathways by radiofrequency current.

    PubMed

    Wang, L; Hu, D; Ding, Y

    1993-12-15

    Tachycardias mediated by atrioventricular accessory pathways, which are refractory to antiarrhythmic drug therapy have been treated both by surgery and by catheter ablation with high energy direct current shock. These procedures have variable success rates and substantial associated morbidity and mortality. Radiofrequency ablation, a newer, low-energy technique is potentially safer and more effective. Of 110 patients with 117 accessory pathways, 101 were located on the left side and 16 on the right. Accessory pathway conduction was abolished permanently in 101 (91.8%) patients. VA conduction dissociation and VA decremental conduction were found in 88 and 13 successful patients, respectively. Four (3.9%) patients with decremental VA conduction suffered arrhythmia recurrence after a mean of 8 months follow-up. Complications developed in two patients including right femoral vein thrombosis and left ventricular insufficiency. There were no deaths from the procedure. We conclude that radiofrequency current ablation is a safe and effective interventional modality for patients with symptomatic tachycardias mediated by atrioventricular accessory pathways. PMID:8112920

  17. Radio-frequency identification: its potential in healthcare.

    PubMed

    2005-05-01

    Radio-frequency identification (RFID) technology is just starting to make inroads into healthcare. RFID uses radio-frequency tags attached to people or objects to provide identification, tracking, security, and other functions that fall under the general heading of automatic identification and data capture (AIDC). In the retail supply chain, RFID is already well established as a way to reduce theft and track objects from manufacture through shipment to delivery. In healthcare, basic RFID is already being used to track patients for anti-elopement and anti-abduction programs. As more sophisticated systems move into hospitals, RFID is also beginning to see use to provide more extensive patient identification than traditional bar coding can, and to track and locate capital equipment within the hospital. In years to come, RFID could be used for a variety of applications, including tracking and matching blood for transfusions, tracking pharmaceuticals, and combating the counterfeiting of medical products. RFID may ultimately be used for many of the functions currently carried out using bar coding--but not until the cost of RFID comes down. For the foreseeable future, the two technologies are likely to be used in tandem in many hospitals. In this article, we describe the components and operation of RFID systems and detail the different ways in which these systems are being used, and could be used, in hospitals. PMID:16048121

  18. Polarimetric assessment of healthy and radiofrequency ablated porcine myocardial tissue.

    PubMed

    Ahmad, Iftikhar; Gribble, Adam; Ikram, Masroor; Pop, Mihaela; Vitkin, Alex

    2016-07-01

    Radiofrequency (RF) ablation offers a potential treatment for cardiac arrhythmia, where properly titrated energy delivered at critical sites can destroy arrhythmogenic foci. The resulting ablation lesion typically consists of a core (coagulative necrosis) surrounded by a rim of mixed viable and non-viable cells. The extent of the RF lesion is difficult to delineate with current imaging techniques. Here, we explore polarization signatures of ten ex-vivo samples from untreated (n = 5) and RF ablated porcine hearts (n = 5), in backscattered geometry through Mueller matrix polarimetry. Significant differences (p < 0.01) in depolarization, ΔT , were observed between the healthy, RF ablated and rim regions. Linear retardance, δ, was significantly lower in the core and rim regions compared to healthy regions (p < 0.05). The results demonstrate a novel application of polarimetry, namely the characterization of RF ablation extent in myocardium, including the visualization of the important lesion rim region. White light photo (top) of porcine myocardium tissue with radiofrequency ablation lesion and corresponding depolarization map (bottom). Depolarization is useful for visualizing the lesion core and rim. PMID:26394151

  19. Optimal cutoff threshold for calcium quantification in isotropic CT calcium scans by validating against registered intravascular ultrasound with radiofrequency backscatter.

    PubMed

    Dhungel, Abinashi; Qian, Zhen; Vazquez, Gustavo; Rinehart, Sarah; Weeks, Michael; Voros, Szilard

    2012-01-01

    3D Computed Tomography (CT) provides noninvasive, low-radiation method of coronary artery calcium (CAC) measurement. Conventional CAC images are acquired on multidetector-row CT scanners without contrast, and reconstructed with 3 mm slice thickness. The calcium volume is quantified by registering voxels with attenuation values greater than or equal to 130 Hounsfield Unit (HU). In isotropic CAC images with 0.5 mm slice thickness obtained from 320-detector row CT, the optimal value of attenuation cutoff threshold is unknown. In this paper we find the optimal cutoff threshold for calcium quantification in isotropic CT calcium scans by validating against registered intravascular ultrasound with radiofrequency backscatter (IVUS/VH). From the statistical analysis of calcium data obtained from the images of 9 patients we found a range of optimal thresholds and the conventional threshold of 130 HU was in the range. Further, the optimal values were different for individual patients. PMID:23367046

  20. The Biological Effects of Quadripolar Radiofrequency Sequential Application: A Human Experimental Study

    PubMed Central

    Cornaglia, Antonia Icaro; Faga, Angela; Scevola, Silvia

    2014-01-01

    Abstract Objective: An experimental study was conducted to assess the effectiveness and safety of an innovative quadripolar variable electrode configuration radiofrequency device with objective measurements in an ex vivo and in vivo human experimental model. Background data: Nonablative radiofrequency applications are well-established anti-ageing procedures for cosmetic skin tightening. Methods: The study was performed in two steps: ex vivo and in vivo assessments. In the ex vivo assessments the radiofrequency applications were performed on human full-thickness skin and subcutaneous tissue specimens harvested during surgery for body contouring. In the in vivo assessments the applications were performed on two volunteer patients scheduled for body contouring surgery at the end of the study. The assessment methods were: clinical examination and medical photography, temperature measurement with thermal imaging scan, and light microscopy histological examination. Results: The ex vivo assessments allowed for identification of the effective safety range for human application. The in vivo assessments allowed for demonstration of the biological effects of sequential radiofrequency applications. After a course of radiofrequency applications, the collagen fibers underwent an immediate heat-induced rearrangement and were partially denaturated and progressively metabolized by the macrophages. An overall thickening and spatial rearrangement was appreciated both in the collagen and elastic fibers, the latter displaying a juvenile reticular pattern. A late onset in the macrophage activation after sequential radiofrequency applications was appreciated. Conclusions: Our data confirm the effectiveness of sequential radiofrequency applications in obtaining attenuation of the skin wrinkles by an overall skin tightening. PMID:25244081

  1. A Method for Safety Testing of Radiofrequency/Microwave-Emitting Devices Using MRI

    PubMed Central

    Alon, Leeor; Cho, Gene Y.; Yang, Xing; Sodickson, Daniel K.; Deniz, Cem M.

    2015-01-01

    Purpose Strict regulations are imposed on the amount of radiofrequency (RF) energy that devices can emit to prevent excessive deposition of RF energy into the body. In this study, we investigated the application of MR temperature mapping and 10-g average specific absorption rate (SAR) computation for safety evaluation of RF-emitting devices. Methods Quantification of the RF power deposition was shown for an MRI-compatible dipole antenna and a non–MRI-compatible mobile phone via phantom temperature change measurements. Validation of the MR temperature mapping method was demonstrated by comparison with physical temperature measurements and electromagnetic field simulations. MR temperature measurements alongside physical property measurements were used to reconstruct 10-g average SAR. Results The maximum temperature change for a dipole antenna and the maximum 10-g average SAR were 1.83° C and 12.4 W/kg, respectively, for simulations and 1.73° C and 11.9 W/kg, respectively, for experiments. The difference between MR and probe thermometry was <0.15° C. The maximum temperature change and the maximum 10-g average SAR for a cell phone radiating at maximum output for 15 min was 1.7° C and 0.54 W/kg, respectively. Conclusion Information acquired using MR temperature mapping and thermal property measurements can assess RF/microwave safety with high resolution and fidelity. PMID:25424724

  2. Should radiofrequency current ablation be performed in asymptomatic patients with the Wolff-Parkinson-White syndrome?

    PubMed

    Steinbeck, G

    1993-03-01

    The exiting new method of ablation of accessory pathways using radiofrequency current applied by catheters will dramatically change our therapeutic decisions in these patients in the near future. This brief survey reviews the existing literature about the risk of the disease as well as of the procedure of catheter ablation. From these data, the risk of sudden death appears to be extremely low in asymptomatic Wolff-Parkinson-White (WPW) individuals. Side effects of catheter ablation may result from the invasive procedure as well as from radiation exposure (the latter to the patient as well as to operating physicians). While the complication rate in experienced centers is extremely low, a multicenter registry of the success and complication rate is urgently needed in view of the many centers starting with catheter ablation. Based on a subjective benefit-to-risk analysis, asymptomatic WPW individuals should be offered catheter ablation only under special circumstances (high risk profession, athletes, family history of sudden death). On the other hand, catheter ablation need not be and should not be considered generally in asymptomatic individuals with WPW pattern. Finally, this author cannot imagine that the energy, time, and money spent for mass screening and eventual catheter ablation of asymptomatic WPW individuals with its attending risks can be outweighed by the potential benefits for these asymptomatic individuals. PMID:7681970

  3. Effects of field orientation during 700-MHz radiofrequency irradiation of rats

    SciTech Connect

    Frei, M.R.; Jauchem, J.R.; Padilla, J.M. )

    1989-01-01

    Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 700-MHz continuous-wave radiofrequency radiation (RFR) in both E and H orientations. Irradiation was conducted at whole-body average specific absorption rates (SARs) of 9.2 and 13.0 W/kg (E and H, respectively) that resulted in approximately equivalent colonic specific heating rates (SHRs). Exposures were performed to repeatedly increase colonic temperature by 1 degree C (38.5 to 39.5 degrees C). Tympanic, tail, left and right subcutaneous (toward and away from RFR source), and colonic temperatures, arterial blood pressure, and respiratory rate were continuously recorded. In spite of equivalent colonic SHRs and the reduced E-orientation average SAR, the right subcutaneous, tympanic, and tail SARs, SHRs and absolute temperature increases were significantly greater in E than in H orientation. The cooling rate at all monitoring sites was also significantly greater in E than in H orientation. Heart rate and mean arterial blood pressure significantly increased during irradiation; however, changes between orientations were not different. Respiratory rate significantly increased during irradiation in H, but not in E orientation. These results indicate that during resonant frequency irradiation, differences occur in the pattern of heat deposition between E- and H-orientation exposure. When compared with previous investigations performed at supraresonant frequencies, the lower level of cardiovascular change in this study was probably related to the lower periphery-to-core thermal gradient.

  4. Effects of field orientation during 700-MHz radiofrequency irradiation of rats

    SciTech Connect

    Frei, M.R.; Jauchem, J.R.; Padilla, J.M.

    1989-01-01

    Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 700-MHz continuous-wave radiofrequency radiation (RFR) in both E and H orientations. Irradiation was conducted at whole-body average specific absorption rates (SARs) of 9.2 and 13.0 W/kg (E and H, respectively) that resulted in approximately equivalent colonic specific heating rates (SHRs). Exposures were performed to repeatedly increase colonic temperature by 1 deg C (38.5 to 39.5 deg C). Tympanic, tail, left and right subcutaneous (toward and away from RFR source), and colonic temperatures, arterial blood pressure, and respiratory rate were continuously recorded. In spite of equivalent colonic SHRs and the reduced E-orientation average SAR, the right subcutaneous, tympanic, and tail SARs, SHRs and absolute temperature increases were significantly greater in E than in H orientation. The cooling rate at all monitoring sites was also significantly greater in E than in H orientation. Heart rate and mean arterial blood pressure significantly increased during irradiation; however, changer between orientations were not different. Respiratory rate significantly increased during irradiation in H, but not in E orientation. These results indicate that during resonant frequency irradiation, differences occur in the pattern of heat deposition between E- and H-orientation exposure. When compared with previous investigations performed at supraresonant frequencies, the lower level of cardiovascular change in this study was probably related to the lower periphery-to-core thermal gradient.

  5. Reversibly Stretchable, Optically Transparent Radio-Frequency Antennas Based on Wavy Ag Nanowire Networks.

    PubMed

    Kim, Byoung Soo; Shin, Keun-Young; Pyo, Jun Beom; Lee, Jonghwi; Son, Jeong Gon; Lee, Sang-Soo; Park, Jong Hyuk

    2016-02-01

    We report a facile approach for producing reversibly stretchable, optically transparent radio-frequency antennas based on wavy Ag nanowire (NW) networks. The wavy configuration of Ag NWs is obtained by floating the NW networks on the surface of water, followed by compression. Stretchable antennas are prepared by transferring the compressed NW networks onto elastomeric substrates. The resulting antennas show excellent performance under mechanical deformation due to the wavy configuration, which allows the release of stress applied to the NWs and an increase in the contact area between NWs. The antennas formed from the wavy NW networks exhibit a smaller return loss and a higher radiation efficiency when strained than the antennas formed from the straight NW networks, as well as an improved stability in cyclic deformation tests. Moreover, the wavy NW antennas require a relatively small quantity of NWs, which leads to low production costs and provides an optical transparency. These results demonstrate the potential of these wavy Ag NW antennas in applications of wireless communications for wearable systems. PMID:26760896

  6. Successful management of a refractory case of postoperative herniorrhaphy pain with extended duration pulsed radiofrequency

    PubMed Central

    Thapa, D; Ahuja, V; Verma, P; Das, C

    2016-01-01

    Chronic postsurgical pain (CPSP) is a distressful condition following hernia surgery. A 25-year-old, 55 kg male patient presented with severe pain on the right side of the lower abdomen that radiated to the testicle and the inner side of the thigh. Patient was symptomatic since 5 months following inguinal herniorrhaphy surgery. The pain was not relieved with pharmacological and interventional nerve blocks. An ultrasound-guided ilioinguinal-iliohypogastric (II-IH) block with extended duration (42°C, four cycles of 120 s each) pulsed radiofrequency (PRF) and a diagnostic genital branch of genitofemoral nerve (GGFN) block provided pain relief. After 1-month, an extended duration PRF in GGFN resulted in complete resolution of symptoms. During a regular follow-up of 9 months, patient reported an improved quality-of-life. We believe the successful management of CPSP following hernia repair with single extended duration PRF of II-IH and GGFN has not been described in the literature. PMID:26955321

  7. Radiofrequency ablation in primary non-small cell lung cancer: What a radiologist needs to know

    PubMed Central

    Bhatia, Shivank; Pereira, Keith; Mohan, Prasoon; Narayanan, Govindarajan; Wangpaichitr, Medhi; Savaraj, Niramol

    2016-01-01

    Lung cancer continues to be one of the leading causes of death worldwide. In advanced cases of lung cancer, a multimodality approach is often applied, however with poor local control rates. In early non-small cell lung cancer (NSCLC), surgery is the standard of care. Only 15-30% of patients are eligible for surgical resection. Improvements in imaging and treatment delivery systems have provided new tools to better target these tumors. Stereotactic body radiation therapy (SBRT) has evolved as the next best option. The role of radiofrequency ablation (RFA) is also growing. Currently, it is a third-line option in stage 1 NSCLC, when SBRT cannot be performed. More recent studies have demonstrated usefulness in recurrent tumors and some authors have also suggested combination of RFA with other modalities in larger tumors. Following the National Lung Screening Trial (NLST), screening by low-dose computed tomography (CT) has demonstrated high rates of early-stage lung cancer detection in high-risk populations. Hence, even considering the current role of RFA as a third-line option, in view of increasing numbers of occurrences detected, the number of potential RFA candidates may see a steep uptrend. In view of all this, it is imperative that interventional radiologists be familiar with the techniques of lung ablation. The aim of this article is to discuss the procedural technique of RFA in the lung and review the current evidence regarding RFA for NSCLC. PMID:27081229

  8. Remote monitoring of emission activity level from NPP using radiofrequencies 1420, 1665, 1667 MHz in real time.

    PubMed

    Kolotkov, Gennady; Penin, Sergei

    2013-01-01

    The Fukushima nuclear accident showed the importance of timely monitoring and detection of radioactive emissions released from enterprises of the nuclear fuel cycle. Nuclear power plants (NPP) working continuously are a stationary source of gas-aerosol emissions which presented in a ground surface layer persistently. Following radioactive emission, untypical effects can be observed, for example: the occurrences of areas with increased ionization, and increased concentration of some gases caused by photochemical reactions. The gases themselves and their characteristic radiation can be markers of radioactivity and can be monitored by a passive method. Hydrogen atom (H) and hydroxyl radical (OH) are formed in a radioactive plume by radiolysis of water molecules and other hydrogen-containing air components by the high energy electrons from beta-decay of radionuclides. The hydrogen atom and hydroxyl radical can spontaneously radiate at 1420 MHz and 1665-1667 MHz respectively. The passive method of remote monitoring of radiation levels using radio-frequencies of H and OH from radioactive emissions of NPP is described. The model data is indicative of the monitoring of radiation levels using these frequencies. PMID:22885151

  9. Efficiency limits for the rectification of solar radiation

    NASA Astrophysics Data System (ADS)

    Mashaal, Heylal; Gordon, Jeffrey M.

    2013-05-01

    Efficiency limits for rectifying (converting AC to DC) incoherent broadband radiation are presented, prompted by establishing a fundamental bound for solar rectennas. For an individual full-wave rectifier, the bound is 2/π. The efficiency boosts attainable with cascaded rectifiers are also derived. The derivation of the broadband limit follows from the analysis of an arbitrary number of random-phase sinusoidal signals, which is also relevant for harvesting ambient radio-frequency radiation from a discrete number of uncorrelated sources.

  10. Variable frequency matching to a radiofrequency source immersed in vacuum

    NASA Astrophysics Data System (ADS)

    Charles, C.; Boswell, R. W.; Bish, A.

    2013-09-01

    A low-weight (0.12 kg) low-volume fixed ceramic capacitor impedance matching system is developed for frequency agile tuning of a radiofrequency (rf) Helicon plasma thruster. Three fixed groups of capacitors are directly mounted onto a two loop rf antenna with the thruster immersed in a vacuum chamber. Optimum plasma tuning at the resonance frequency is demonstrated via measurements of the load impedance, power transfer efficiency and plasma density versus driving frequency in the 12.882-14.238 MHz range. The resonance frequency with the plasma on is higher than the resonance frequency in vacuum. The minimum rf power necessary for ignition decreases when the ignition frequency is shifted downwards from the resonance frequency. This development has direct applications in space qualification and space use of rf plasma thrusters.

  11. Multifunctional radio-frequency generator for cold atom experiments

    NASA Astrophysics Data System (ADS)

    Wei, Chun-hua; Yan, Shu-hua

    2016-05-01

    We present a low cost radio-frequency (RF) generator suitable for experiments with cold atoms. The RF source achieves a sub-hertz frequency with tunable resolution from 0 MHz to 400 MHz and a maximum output power of 33 dBm. Based on a direct digital synthesizer (DDS) chip, we implement a ramping capability for frequency, amplitude and phase. The system can also operate as an arbitrary waveform generator. By measuring the stability in a duration of 600 s, we find the presented device performs comparably as Agilent33522A in terms of short-term stability. Due to its excellent performance, the RF generator has been already applied to cold atom trapping experiments.

  12. A practical method to evaluate radiofrequency exposure of mast workers.

    PubMed

    Alanko, Tommi; Hietanen, Maila

    2008-01-01

    Assessment of occupational exposure to radiofrequency (RF) fields in telecommunication transmitter masts is a challenging task. For conventional field strength measurements using manually operated instruments, it is difficult to document the locations of measurements while climbing up a mast. Logging RF dosemeters worn by the workers, on the other hand, do not give any information about the location of the exposure. In this study, a practical method was developed and applied to assess mast workers' exposure to RF fields and the corresponding location. This method uses a logging dosemeter for personal RF exposure evaluation and two logging barometers to determine the corresponding height of the worker's position on the mast. The procedure is not intended to be used for compliance assessments, but to indicate locations where stricter assessments are needed. The applicability of the method is demonstrated by making measurements in a TV and radio transmitting mast. PMID:19054796

  13. Spatially periodic radio-frequency quadrupole focusing linac

    NASA Astrophysics Data System (ADS)

    Kolomiets, A. A.; Plastun, A. S.

    2015-12-01

    The new design for a spatially periodical rf quadrupole focusing linac is proposed. It consists of accelerating gaps formed between conventional cylindrical drift tubes, between drift tubes and rf quadrupoles with nonzero axial potential, and inside these rf quadrupoles, formed in the same way as in a conventional radio-frequency quadrupole (RFQ) linac with modulated electrodes. Such a combination provides both higher energy gain rate than conventional RFQ and stability of transverse motion for ion beams. The structure can be designed using various combinations of quadrupoles and drift tubes. Some options are considered in the paper using the smooth approximation method and computer simulation of beam dynamics. Transverse stability of particles has been studied. The proposed structure can provide suppression of rf defocusing effects on transverse beam dynamics. Some limitations of the spatially periodic rf quadrupole structure are mentioned.

  14. Ethical implications of implantable radiofrequency identification (RFID) tags in humans.

    PubMed

    Foster, Kenneth R; Jaeger, Jan

    2008-08-01

    This article reviews the use of implantable radiofrequency identification (RFID) tags in humans, focusing on the VeriChip (VeriChip Corporation, Delray Beach, FL) and the associated VeriMed patient identification system. In addition, various nonmedical applications for implanted RFID tags in humans have been proposed. The technology offers important health and nonhealth benefits, but raises ethical concerns, including privacy and the potential for coercive implantation of RFID tags in individuals. A national discussion is needed to identify the limits of acceptable use of implantable RFID tags in humans before their use becomes widespread and it becomes too late to prevent misuse of this useful but ethically problematic technology. PMID:18802863

  15. Radiofrequency fields associated with the Itron smart meter.

    PubMed

    Tell, R A; Sias, G G; Vazquez, A; Sahl, J; Turman, J P; Kavet, R I; Mezei, G

    2012-08-01

    This study examined radiofrequency (RF) emissions from smart electric power meters deployed in two service territories in California for the purpose of evaluating potential human exposure. These meters included transmitters operating in a local area mesh network (RF LAN, ∼250 mW); a cell relay, which uses a wireless wide area network (WWAN, ∼1 W); and a transmitter serving a home area network (HAN, ∼70 mW). In all instances, RF fields were found to comply by a wide margin with the RF exposure limits established by the US Federal Communications Commission. The study included specialised measurement techniques and reported the spatial distribution of the fields near the meters and their duty cycles (typically <1 %) whose value is crucial to assessing time-averaged exposure levels. This study is the first to characterise smart meters as deployed. However, the results are restricted to a single manufacturer's emitters. PMID:22234423

  16. Radio-frequency ion deflector for mass separation

    SciTech Connect

    Schlösser, Magnus Rudnev, Vitaly; Ureña, Ángel González

    2015-10-15

    Electrostatic cylindrical deflectors act as energy analyzer for ion beams. In this article, we present that by imposing of a radio-frequency modulation on the deflecting electric field, the ion transmission becomes mass dependent. By the choice of the appropriate frequency, amplitude, and phase, the deflector can be used as mass filter. The basic concept of the new instrument as well as simple mathematic relations are described. These calculations and further numerical simulations show that a mass sensitivity is achievable. Furthermore, we demonstrate the proof-of-principle in experimental measurements, compare the results to those of from a 1 m linear time-of-flight spectrometer, and comment on the mass resolution of the method. Finally, some potential applications are indicated.

  17. Percutaneous radiofrequency ablation: minimally invasive therapy for renal tumors.

    PubMed

    Ahrar, Kamran; Wallace, Michael J; Matin, Surena F

    2006-12-01

    Currently, up to 60% of renal tumors are detected incidentally by abdominal imaging. Most of these tumors are small and localized to the kidney. Owing to the shift to lower stage at diagnosis, radical nephrectomy has fallen out of favor and has been replaced by nephron-sparing surgery. Currently, partial nephrectomy is the treatment of choice for patients with small renal tumors. As the trend towards less invasive therapy continues, laparoscopic and percutaneous ablation techniques have gained popularity for the treatment of renal tumors in patients who are high-risk surgical candidates, or have a solitary kidney, limited renal function or multifocal disease. Percutaneous radiofrequency ablation is a safe, minimally invasive treatment option for those patients. PMID:17181487

  18. Temperature Mapping of Nitrogen-doped Niobium Superconducting Radiofrequency Cavities

    SciTech Connect

    Makita, Junki; Ciovati, Gianluigi; Dhakal, Pashupati

    2015-09-01

    It was recently shown that diffusing nitrogen on the inner surface of superconducting radiofrequency (SRF) cavities at high temperature can improve the quality factor of the niobium cavity. However, a reduction of the quench field is also typically found. To better understand the location of rf losses and quench, we used a thermometry system to map the temperature of the outer surface of ingot Nb cavities after nitrogen doping and electropolishing. Surface temperature of the cavities was recorded while increasing the rf power and also during the quenching. The results of thermal mapping showed no precursor heating on the cavities and quenching to be ignited near the equator where the surface magnetic field is maximum. Hot-spots at the equator area during multipacting were also detected by thermal mapping.

  19. Optical emission study of radio-frequency excited toluene plasma.

    PubMed

    Lee, Szetsen; Liu, Shiao-Jun; Liang, Rui-Ji

    2008-12-25

    UV-visible emission spectra of radio-frequency (rf) excited toluene plasma were studied. Benzyl radicals as well as toluene monomer and excimer were observed in toluene plasma. It was found that the intensities, peak positions, and linewidths of monomer and excimer emission bands exhibit strong dependence on rf power and plasma processing time. This can be ascribed to photochemical reactions in plasma. Gas-chromatographic analysis of the deposition products from toluene plasma indicated that the main component was bibenzyl. Spectroscopic evidence has shown that the bibenzyl molecule was formed by the coupling reaction between two benzyl radicals in plasma. The spectroscopic characteristics of toluene monomer and excimer are correlated with a kinetic model in plasma. PMID:19049320

  20. Phase responses of harmonics reflected from radio-frequency electronics

    NASA Astrophysics Data System (ADS)

    Mazzaro, Gregory J.; McGowan, Sean F.; Gallagher, Kyle A.; Sherbondy, Kelly D.; Martone, Anthony F.; Narayanan, Ram M.

    2016-05-01

    The phase responses of nonlinear-radar targets illuminated by stepped frequencies are studied. Data is presented for an experimental radar and two commercial electronic targets at short standoff ranges. The amplitudes and phases of harmonics generated by each target at each frequency are captured over a 100-MHz-wide transmit band. As in the authors' prior work, target detection is demonstrated by receiving at least one harmonic of at least one transmit frequency. In the present work, experiments confirm that the phase of a harmonic reflected from a radio-frequency electronic target at a standoff distance is linear versus frequency. Similar to traditional wideband radar, the change of the reflected phase with respect to frequency indicates the range to the nonlinear target.

  1. A morphological algorithm for improving radio-frequency interference detection

    NASA Astrophysics Data System (ADS)

    Offringa, A. R.; van de Gronde, J. J.; Roerdink, J. B. T. M.

    2012-03-01

    A technique is described that is used to improve the detection of radio-frequency interference in astronomical radio observatories. It is applied on a two-dimensional interference mask after regular detection in the time-frequency domain with existing techniques. The scale-invariant rank (SIR) operator is defined, which is a one-dimensional mathematical morphology technique that can be used to find adjacent intervals in the time or frequency domain that are likely to be affected by RFI. The technique might also be applicable in other areas in which morphological scale-invariant behaviour is desired, such as source detection. A new algorithm is described, that is shown to perform quite well, has linear time complexity and is fast enough to be applied in modern high resolution observatories. It is used in the default pipeline of the LOFAR observatory.

  2. Radio-frequency ion deflector for mass separation.

    PubMed

    Schlösser, Magnus; Rudnev, Vitaly; González Ureña, Ángel

    2015-10-01

    Electrostatic cylindrical deflectors act as energy analyzer for ion beams. In this article, we present that by imposing of a radio-frequency modulation on the deflecting electric field, the ion transmission becomes mass dependent. By the choice of the appropriate frequency, amplitude, and phase, the deflector can be used as mass filter. The basic concept of the new instrument as well as simple mathematic relations are described. These calculations and further numerical simulations show that a mass sensitivity is achievable. Furthermore, we demonstrate the proof-of-principle in experimental measurements, compare the results to those of from a 1 m linear time-of-flight spectrometer, and comment on the mass resolution of the method. Finally, some potential applications are indicated. PMID:26520948

  3. Bronchopleural Fistula After Radiofrequency Ablation of Lung Tumours

    SciTech Connect

    Cannella, Mathieu; Cornelis, Francois; Descat, Edouard; Ferron, Stephane; Carteret, Thibault; Castagnede, Hugues; Palussiere, Jean

    2011-02-15

    The present article describes two cases of bronchopleural fistula (BPF) occurring after radiofrequency ablation of lung tumors. Both procedures were carried out using expandable multitined electrodes, with no coagulation of the needle track. After both ablations, ground-glass opacities encompassed the nodules and abutted the visceral pleura. The first patient had a delayed pneumothorax, and the second had a recurrent pneumothorax. Both cases of BPF were diagnosed on follow-up computed tomography chest scans (i.e., visibility of a distinct channel between the lung or a peripheral bronchus and the pleura) and were successfully treated with chest tubes alone. Our goal is to highlight the fact that BPF can occur without needle-track coagulation and to suggest that minimally invasive treatment is sufficient to cure BPFs of this specific origin.

  4. Superconducting radio-frequency modules test faciilty operating experience

    SciTech Connect

    Soyars, W.; Bossert, R.; Darve, C.; Degraff, B.; Klebaner, A.; Martinez, A.; Pei, L.; Theilacker, J.; /Fermilab

    2007-07-01

    Fermilab is heavily engaged and making strong technical contributions to the superconducting radio-frequency research and development program (SRF R&D). Four major SRF test areas are being constructed to enable vertical and horizontal cavity testing, as well as cryomodule testing. The existing Fermilab cryogenic infrastructure has been modified to service Fermilab SRF R&D needs. The first stage of the project has been successfully completed, which allows for distribution of cryogens for a single cavity cryomodule using the existing Cryogenic Test Facility (CTF) that houses three Tevatron satellite refrigerators. The cooling capacity available for cryomodule testing at MDB results from the liquefaction capacity of the CTF cryogenic system. The cryogenic system for a single 9-cell cryomodule is currently operational. The paper describes the status, challenges and operational experience of the initial phase of the project.

  5. Radiofrequency ablation for neuroendocrine liver metastases: a systematic review.

    PubMed

    Mohan, Helen; Nicholson, Patrick; Winter, Des C; O'Shea, Donal; O'Toole, Dermot; Geoghegan, Justin; Maguire, Donal; Hoti, Emir; Traynor, Oscar; Cantwell, Colin P

    2015-07-01

    To determine the efficacy of radiofrequency (RF) ablation in neuroendocrine tumor (NET) liver metastases. A systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eight studies were included (N = 301). Twenty-six percent of RF ablation procedures were percutaneous (n = 156), with the remainder conducted at surgery. Forty-eight percent of patients had a concomitant liver resection. Fifty-four percent of patients presented with symptoms, with 92% reporting symptom improvement following RF ablation (alone or in combination with surgery). The median duration of symptom improvement was 14-27 months. However, recurrence was common (63%-87%). RF ablation can provide symptomatic relief in NET liver metastases alone or in combination with surgery. PMID:25840836

  6. Protein adsorption enhanced radio-frequency heating of silica nanoparticles

    PubMed Central

    Wosik, Jarek; Pande, Rohit; Xie, Leiming; Ketharnath, Dhivya; Srinivasan, Srimeenakshi; Godin, Biana

    2013-01-01

    Measurements of specific-absorption-rate (SAR) of silica 30, 50, and 100 nm nanoparticles (NP) suspended in water were carried out at 30 MHz in 7 kV/m radio-frequency (rf) electric field. Size dependent, NP-suspension interface related heating of silica NP was observed. To investigate a possible mechanism of heating, bovine serum albumin was adsorbed on the surface of silica NPs in suspension. It resulted in significant enhancement of SAR when compared to bare silica NPs. A calorimetric and rf loss model was used to calculate effective conductivity of silica NP with/without adsorbed albumin as a function of silica size and albumin concentration. PMID:23964135

  7. Cardiac Radiofrequency Ablation: A Clinical Update for Nurses.

    PubMed

    Shoulders, Bridget; Mauriello, Jillian; Shellman, Tamika; Follett, Corrinne

    2016-01-01

    The field of electrophysiology (EP) has rapidly evolved from a focus on diagnostic procedures to an emphasis on interventions. Many cardiac arrhythmias traditionally treated with antiarrhythmic agents, cardioversion, or cardiac surgery are now routinely cured with cardiac ablation. To optimally manage the care of cardiac ablation patients, it is essential that nurses have an understanding of the EP procedures and related nursing implications. There are extensive evidence-based resources available in the medical literature; however, there are limited publications geared toward nurses caring for cardiac ablation patients.This article provides an overview of EP diagnostic and cardiac radio-frequency ablation procedures for select atrial and ventricular tachyarrhythmias. Evidence-based nursing practices related to postprocedure care will be addressed. The objective of this article is to increase nurses' knowledge of common cardiac ablation procedures and the nursing management of the patient postprocedure. PMID:27487751

  8. Radiofrequency ablation of a misdiagnosed Brodie’s abscess

    PubMed Central

    Chan, RS; Abdullah, BJJ; Aik, S; Tok, CH

    2011-01-01

    Radiofrequency ablation (RFA) therapy is recognised as a safe and effective treatment option for osteoid osteoma. This case report describes a 27-year-old man who underwent computed tomography (CT)-guided percutaneous RFA for a femoral osteoid osteoma, which was diagnosed based on his clinical presentation and CT findings. The patient developed worsening symptoms complicated by osteomyelitis after the procedure. His clinical progression and subsequent MRI findings had led to a revised diagnosis of a Brodie’s abscess, which was further supported by the eventual resolution of his symptoms following a combination of antibiotics treatment and surgical irrigations. This case report illustrates the unusual MRI features of osteomyelitis mimicking soft tissue tumours following RFA of a misdiagnosed Brodie’s abscess and highlights the importance of a confirmatory histopathological diagnosis for an osteoid osteoma prior to treatment. PMID:22291860

  9. Reactivable passive radio-frequency identification temperature indicator

    NASA Astrophysics Data System (ADS)

    Windl, Roman; Bruckner, Florian; Abert, Claas; Suess, Dieter; Huber, Thomas; Vogler, Christoph; Satz, Armin

    2015-05-01

    A low cost, passive radio-frequency identification (RFID) temperature indicator with (re-) activation at any point of time is presented. The capability to detect a temperature excursion is realized by magnets and a solution with a melting point at the critical temperature. As the critical temperature is exceeded, a magnetic indicator switches to non-reversible and this can be monitored via a giant magnetoresistance sensor connected to a RFID tag. Depending on the solutions or metal alloys, detection of critical temperatures in a wide range from below 0 °C and up to more than 100 °C is possible. The information if a threshold temperature was exceeded (indicator state) as well as the identification number, current temperature, and user defined data can be obtained via RFID.

  10. Radio-frequency association of molecules: an assisted Feshbach resonance

    NASA Astrophysics Data System (ADS)

    Beaufils, Q.; Crubellier, A.; Zanon, T.; Laburthe-Tolra, B.; Maréchal, É.; Vernac, L.; Gorceix, O.

    2010-01-01

    We develop a theoretical model to describe the radio-frequency (rf) induced coupling of a pair of colliding atoms to a Feshbach molecule when a magnetic field arbitrarily far from the Feshbach resonance is modulated in time. We use the dressed atom picture, and show that the coupling strength in presence of rf is equal to the Feshbach coupling strength multiplied by the square of a Bessel function. The argument of this function is equal to the ratio of the atomic rf Rabi frequency to the rf frequency. We experimentally demonstrate this law by measuring the rate of rf-association of molecules using a Feshbach resonance in d wave collisions between ultra-cold chromium atoms.

  11. RFQ (radio-frequency quadrupole) accelerators for heating thermonuclear plasmas

    SciTech Connect

    Stokes, R.H.; Wangler, T.P.; Crandall, K.R.

    1987-01-01

    The radio-frequency quadrupole (RFQ) accelerator has been developed to generate high-current ion beams for a wide variety of applications. It has also been suggested that this type of accelerator could be used to produce megawatt ion beams to heat thermonuclear reactor plasmas. For a tokamak reactor, an RFQ accelerator can be designed to provide negative deuterium ions that are neutralized before injection through the tokamak magentic field. Also, it may be possible to use singly charged, positive, heavier ions that trasverse the magnetic field with minimal deflection and then become multiply ionized upon striking the tokamak plasma. We present preliminary RFQ beam-dynamics designs for both deuterium and oxygen ions.

  12. {product}Strong focusing and the radiofrequency quadrupole accelerator

    SciTech Connect

    Wangler, T.P.

    1996-02-01

    The {open_quote}{open_quote}New Problems{close_quote}{close_quote} department presents novel problems for use in undergraduate physics courses beyond the introductory level. In this article the problems and solutions use basic principles of electromagnetism to explain strong-focusing accelerator known as the radiofrequency quadrupole. Their solutions use Laplace{close_quote}s equation and require the extraction of information from boundary conditions. They also introduce the quasistatic approximation and show how under appropriate conditions Laplace{close_quote}s equation can be used to solve time-dependent problems. The problems are suitable for a course in electromagnetism and may be of interest for a cours in classical mechanics.

  13. Biological effects and exposure criteria for radiofrequency electromagnetic fields

    SciTech Connect

    Not Available

    1986-01-01

    This report, which begins with a discussion of fundamental studies at the molecular level, presents a review of the subject matter covered in NCRP Report No. 67 on mechanisms of interaction of radiofrequency electromagnetic (RFEM) fields with tissue. The discussion continues to progressively larger scales of interaction, beginning with macromolecular and cellular effects, chromosomal and mutagenic effects, and carcinogenic effects. The scope of the subject matter is then expanded to include systemic effects such as those on reproduction, growth, and development, hematopoiesis and immunology, endocrinology and autonomic nervous function, cardiovascular effects and cerebrovascular effects. The interaction of electromagnetic fields with the central nervous system and special senses is also discussed. Also included are epidemiological studies, a discussion of thermoregulation, and a history of therapeutic applications of RFEM fields. The report concludes with human exposure criteria and rationale.

  14. Characteristics of Radio-Frequency Circuits Utilizing Ferroelectric Capacitors

    NASA Technical Reports Server (NTRS)

    Eskridge, Michael; Gui, Xiao; MacLeod, Todd; Ho, Fat D.

    2011-01-01

    Ferroelectric capacitors, most commonly used in memory circuits and variable components, were studied in simple analog radio-frequency circuits such as the RLC resonator and Colpitts oscillator. The goal was to characterize the RF circuits in terms of frequency of oscillation, gain, etc, using ferroelectric capacitors. Frequencies of oscillation of both circuits were measured and studied a more accurate resonant frequency can be obtained using the ferroelectric capacitors. Many experiments were conducted and data collected. A model to simulate the experimental results will be developed. Discrepancies in gain and frequency in these RF circuits when conventional capacitors are replaced with ferroelectric ones were studied. These results will enable circuit designers to anticipate the effects of using ferroelectric components in their radio- frequency applications.

  15. Laparoscopic Ultrasound-Guided Radiofrequency Ablation of Uterine Fibroids

    SciTech Connect

    Milic, Andrea; Asch, Murray R. Hawrylyshyn, Peter A.; Allen, Lisa M.; Colgan, Terence J.; Kachura, John R.; Hayeems, Eran B.

    2006-08-15

    Four patients with symptomatic uterine fibroids measuring less than 6 cm underwent laparoscopic ultrasound-guided radiofrequency ablation (RFA) using multiprobe-array electrodes. Follow-up of the treated fibroids was performed with gadolinium-enhanced magnetic resonance imaging (MRI) and patients' symptoms were assessed by telephone interviews. The procedure was initially technically successful in 3 of the 4 patients and MRI studies at 1 month demonstrated complete fibroid ablation. Symptom improvement, including a decrease in menstrual bleeding and pain, was achieved in 2 patients at 3 months. At 7 months, 1 of these 2 patients experienced symptom worsening which correlated with recurrent fibroid on MRI. The third, initially technically successfully treated patient did not experience any symptom relief after the procedure and was ultimately diagnosed with adenomyosis. Our preliminary results suggest that RFA is a technically feasible treatment for symptomatic uterine fibroids in appropriately selected patients.

  16. Remotely Triggered Cisplatin Release from Carbon Nanocapsules by Radiofrequency Fields

    PubMed Central

    Raoof, Mustafa; Cisneros, Brandon T.; Guven, Adem; Corr, Stuart J.; Wilson, Lon J.; Curley, Steven A.

    2013-01-01

    The efficacy of nanoparticle-mediated drug delivery is limited by its peri-vascular sequestration, thus necessitating a strategy to trigger drug release from such intra-tumoral nanocarrier-drug depots. In our efforts to explore remotely-activated nanocarriers, we have developed carbon nanocapsules comprised of an ultrashort carbon nanotube shell (US-tubes) loaded with cisplatin (CDDP@US-tubes) and covered with a Pluronic surfactant wrapping to minimize passive release. We demonstrate here that non-invasive radiofrequency (RF) field activation of the CDDP@US-tubes produces heat that causes Pluronic disruption which triggers cisplatin release in an RF-dependent manner. Furthermore, release-dependent cytotoxicity is demonstrated in human hepatocellular carcinoma cell lines. PMID:23228421

  17. Radiofrequency superconductivity applied to free-electron lasers

    SciTech Connect

    Bohn, C.L.; Benson, S.V.

    1998-01-01

    Low wall losses and low wakefields inherent in superconducting radiofrequency (srf) cavities make them attractive candidates for accelerators that operate efficiently at high continuous-wave (cw) gradients. Such accelerators are desirable for free-electron lasers (FELs) that extract high-power cw light from a high-average-current electron beam, or that produce ultrashort-wavelength light from a high-energy electron beam. Efficiency is a prime consideration in the former case, while high electron-beam quality is a prime consideration in the latter case. This paper summarizes the status of FEL projects involving srf accelerators. It also introduces Jefferson Lab`s srf FEL and surveys its design because it is a new machine, with commissioning having commenced in October 1997. Once commissioning is complete, this FEL should produce tunable, cw, kW-level light at 3-6 {mu}m wavelength.

  18. Radiofrequency energy exposure from the Trilliant smart meter.

    PubMed

    Foster, Kenneth R; Tell, Richard A

    2013-08-01

    This paper reviews radiofrequency (RF) field levels produced by electric utility meters equipped with RF transceivers (so-called Smart Meters), focusing on meters from one manufacturer (Trilliant, Redwood City, CA, USA, and Granby, QC, Canada). The RF transmission levels are summarized based on publicly available data submitted to the U.S. Federal Communications Commission supplemented by limited independent measurements. As with other Smart Meters, this meter incorporates a low powered radiofrequency transceiver used for a neighborhood mesh network, in the present case using ZigBee-compliant physical and medium access layers, operating in the 2.45 GHz unlicensed band but with a proprietary network architecture. Simple calculations based on a free space propagation model indicate that peak RF field intensities are in the range of 10 mW m or less at a distance of more than 1-2 m from the meters. However, the duty cycle of transmission from the meters is very low (< 1%). Limited measurements identified pulses from the meter that were consistent with data reported by the vendor to the U.S. Federal Communications Commission. Limited measurements conducted in two houses with the meters were unable to clearly distinguish emissions from the meters from the considerable electromagnetic clutter in the same frequency range from other sources, including Wi-Fi routers and, when it was activated, a microwave oven. These preliminary measurements disclosed the difficulties that would be encountered in characterizing the RF exposures from these meters in homes in the face of background signals from other household devices in the same frequency range. An appendix provides an introduction to Smart Meter technology. The RF transmitters in wireless-equipped Smart Meters operate at similar power levels and in similar frequency ranges as many other digital communications devices in common use, and their exposure levels are very far below U.S. and international exposure limits. PMID

  19. Radiofrequency thermal treatment with chemoradiotherapy for advanced rectal cancer

    PubMed Central

    SHOJI, HISANORI; MOTEGI, MASAHIKO; OSAWA, KIYOTAKA; OKONOGI, NORIYUKI; OKAZAKI, ATSUSHI; ANDOU, YOSHITAKA; ASAO, TAKAYUKI; KUWANO, HIROYUKI; TAKAHASHI, TAKEO; OGOSHI, KYOJI

    2016-01-01

    We previously reported that patients with a clinical complete response (CR) following radiofrequency thermal treatment exhibit significantly increased body temperature compared with other groups, whereas patients with a clinical partial response or stable disease depended on the absence or presence of output limiting symptoms. The aim of this study was to evaluate the correlation among treatment response, Hidaka radiofrequency (RF) output classification (HROC: termed by us) and changes in body temperature. From December 2011 to January 2014, 51 consecutive rectal cancer cases were included in this study. All patients underwent 5 RF thermal treatments with concurrent chemoradiation. Patients were classified into three groups based on HROC: with ≤9, 10–16, and ≥17 points, calculated as the sum total points of five treatments. Thirty-three patients received surgery 8 weeks after treatment, and among them, 32 resected specimens were evaluated for histological response. Eighteen patients did not undergo surgery, five because of progressive disease (PD) and 13 refused because of permanent colostomy. We demonstrated that good local control (ypCR + CR + CRPD) was observed in 32.7% of cases in this study. Pathological complete response (ypCR) was observed in 15.7% of the total 51 patients and in 24.2% of the 33 patients who underwent surgery. All ypCR cases had ≥10 points in the HROC, but there were no patients with ypCR among those with ≤9 points in the HROC. Standardization of RF thermal treatment was performed safely, and two types of patients were identified: those without or with increased temperatures, who consequently showed no or some benefit, respectively, for similar RF output thermal treatment. We propose that the HROC is beneficial for evaluating the efficacy of RF thermal treatment with chemoradiation for rectal cancer, and the thermoregulation control mechanism in individual patients may be pivotal in predicting the response to RF thermal treatment

  20. Radiofrequency catheter septal ablation for hypertrophic obstructive cardiomyopathy in children

    PubMed Central

    Emmel, M.; Sreeram, N.

    2005-01-01

    Background The definitive therapeutic options for symptomatic obstructive cardiomyopathy in childhood are restricted. At present, extensive surgical myectomy is the only procedure that is of proven benefit. Patients and Methods Three patients, aged 5, 11 and 17 years, respectively, with progressive hypertrophic obstructive cardiomyopathy and increasing symptoms were considered for radiofrequency catheter septal ablation. The peak Doppler gradient recorded on several occasions ranged between 50 to 90mmHg. Via a femoral arterial approach, the His bundle was initially plotted and marked using the LocaLisa navigation system. Subsequently, using a cooled tip catheter a series of lesions were placed in the hypertrophied septum, taking care to stay away from the His bundle. A total of 17, 50 and 45 lesions were applied in the three patients. In one case, the procedure was complicated by two episodes of ventricular fibrillation requiring DC cardioversion but without any neurological sequelae. Results The preablation peak-to-peak gradient between left ventricle and aorta was 50 mmHg, 60 mmHg and 60 mmHg, respectively, and remained unchanged immediately after the procedure. All patients were discharged from hospital 48 hours later. Serial measurement of serum troponin T and CK-MB isoenzyme confirmed significant myocardial necrosis. Follow-up echocardiography both at seven days and at six weeks postablation confirmed a beneficial haemodynamic result, with reduction of left ventricular outflow obstruction and relief of symptoms. Conclusion In young children, in whom alcohol-induced septal ablation is not an option, radiofrequency catheter ablation offers an alternative to surgery, with the benefits of repeatability and a lower risk of procedure-related permanent AV block. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:25696442

  1. Successful Treatment of Erythematotelangiectatic Rosacea with Pulsed Light and Radiofrequency

    PubMed Central

    DeVita, Erin C.

    2008-01-01

    Introduction: Many laser and light devices have reported to be successful in the treatment of the flushing, background erythema, and telangiectasias that characterize erythematotelangiectatic rosacea including pulsed dye laser, potassium titanyl phosphate, intense pulsed light, and dual-wavelength lasers. A technology called ELOS (electro-optical synergy) combines pulsed light or laser with bipolar radiofrequency. This combination, developed in 2000, was based on the premise that these two forms of energy could be synergistic. One such device (Aurora SRA—skin-rejuvenation advanced handpiece, Syneron Medical Ltd., Yokneam, Israel) has a light spectrum of 470 to 980nm, energy up to 45J/cm2, and a range of radiofrequency energy of 5 to 25J/cm3 and is indicated for the treatment of vascular and pigmented lesions. Methods: We attempted to quantify the improvement of moderate-to-severe type-1 rosacea after three and five full-face treatments with this modality. Twenty-one patients with moderate-to-severe rosacea underwent five monthly full-face treatments with this device. The patients were evaluated with high-resolution photographs (Canfield Visia CR, Canfield, Fairfield, New Jersey) and self-evaluated via the National Rosacea Society's official “Scorecard.” Results: Erythema and telangiectasia (physician assessed) as well as flushing and global status (patient assessed) achieved improvement that was statistically significant. Five treatments were no more effective than three, although the photographs reveal subtle improvements. There were no significant adverse events. Conclusion: The results of this study suggest that the combination of optical and RF energies is effective for the treatment of rosacea. ELOS, as well as other vascular-focused lasers and light sources, provides an important treatment option for patients who fail medical therapy, reach a plateau in their response to medical therapy, or wish to avoid chronic oral therapy. PMID:21103309

  2. Use of Semiflexible Applicators for Radiofrequency Ablation of Liver Tumors

    SciTech Connect

    Gaffke, G. Gebauer, B.; Knollmann, F.D.; Helmberger, T.; Ricke, J.; Oettle, H.; Felix, R.; Stroszczynski, C.

    2006-04-15

    Purpose. To evaluate the feasibility and potential advantages of the radiofrequency ablation of liver tumors using new MRI-compatible semiflexible applicators in a closed-bore high-field MRI scanner. Methods. We treated 8 patients with 12 malignant liver tumors of different origin (5 colorectal carcinoma, 2 cholangiocellular carcinoma, 1 breast cancer) under MRI guidance. Radiofrequency ablation (RFA) was performed using 5 cm Rita Starburst Semi-Flex applicators (Rita Medical Systems, Milwaukee, WI, USA) which are suitable for MR- and CT-guided interventions and a 150 W RF generator. All interventions were performed in a closed-bore 1.5 T high-field MRI scanner for MRI-guided RFA using fast T1-weighted gradient echo sequences and T2-weighted ultra-turbo spin echo sequences. Control and follow-up MRI examinations were performed on the next day, at 6 weeks, and every 3 months after RFA. Control MRI were performed as double-contrast MRI examinations (enhancement with iron oxide and gadopentetate dimeglumine). All interventions were performed with the patient under local anesthesia and analgo-sedation. Results. The mean diameter of the treated hepatic tumors was 2.4 cm ({+-}0.6 cm, range 1.0-3.2 cm). The mean diameter of induced necrosis was 3.1 cm ({+-}0.4 cm). We achieved complete ablation in all patients. Follow-up examinations over a duration of 7 months ({+-}1.3 months, range 4-9 month) showed a local control rate of 100% in this group of patients. All interventions were performed without major complications; only 2 subcapsular hematomas were documented. Conclusion. RFA of liver tumors using semiflexible applicators in closed-bore 1.5 T scanner systems is feasible. These applicators might simplify the RFA of liver tumors under MRI control. The stiff distal part of the applicator facilitates its repositioning.

  3. Ultrasonography guided percutaneous radiofrequency ablation for hepatic cavernous hemangioma

    PubMed Central

    Cui, Yan; Zhou, Li-Yan; Dong, Man-Ku; Wang, Ping; Ji, Min; Li, Xiao-Ou; Chen, Chang-Wei; Liu, Zi-Pei; Xu, Yong-Jie; Zhang, Hong-Wen

    2003-01-01

    AIM: Hepatic cavernous hemangioma (HCH) is the most common benign tumor of the liver and its management is still controversial. Recent success in situ radiofrequency ablation of hepatic malignancies has led us to consider using this technique in patients with HCH. This study was to assess the efficacy, safety, and complications of percutaneous radiofrequency ablation (PRFA) under ultrasonography guidance in patients with HCH. METHODS: Twelve patients (four men and eight women, age ranged 33-56 years, mean age was 41.7 years) with 15 hepatic cavernous hemangiomas (2.5 cm to 9.5 cm) were treated using the RF-2000 generator and 10-needle LeVeen electrode percutaneously guided by B-ultrasound. Lesions larger than 3 cm were treated by multiple overlapping ablations that encompass the entire lesion as well as a rim of normal liver tissue (approximately 0.5 cm). RESULTS: All the patients who received PRFA therapy had no severe pain, bleeding or bile leakage during and after the procedures. Nine to 34 months’ follow-up (mean, 21 months) by ultrasound and/or spiral CT scan demonstrated that the ablated lesions in this group were shrunk remarkably, and the shrunken range was 38%-79% (mean, 67% per 21 months). The contrast enhancement was disappeared within the tumor or at its periphery in all cases on spiral CT scans obtained 3 to 6 months after treatment. CONCLUSION: The results of this study suggest that PRFA therapy is a mini-invasive, simple, safe, and effective method for the treatment of selected patients with HCH. PMID:12970923

  4. Factors Limiting Complete Tumor Ablation by Radiofrequency Ablation

    SciTech Connect

    Paulet, Erwan Aube, Christophe; Pessaux, Patrick; Lebigot, Jerome; Lhermitte, Emilie; Oberti, Frederic; Ponthieux, Anne; Cales, Paul; Ridereau-Zins, Catherine; Pereira, Philippe L.

    2008-01-15

    The purpose of this study was to determine radiological or physical factors to predict the risk of residual mass or local recurrence of primary and secondary hepatic tumors treated by radiofrequency ablation (RFA). Eighty-two patients, with 146 lesions (80 hepatocellular carcinomas, 66 metastases), were treated by RFA. Morphological parameters of the lesions included size, location, number, ultrasound echogenicity, computed tomography density, and magnetic resonance signal intensity were obtained before and after treatment. Parameters of the generator were recorded during radiofrequency application. The recurrence-free group was statistically compared to the recurrence and residual mass groups on all these parameters. Twenty residual masses were detected. Twenty-nine lesions recurred after a mean follow-up of 18 months. Size was a predictive parameter. Patients' sex and age and the echogenicity and density of lesions were significantly different for the recurrence and residual mass groups compared to the recurrence-free group (p < 0.05). The presence of an enhanced ring on the magnetic resonance control was more frequent in the recurrence and residual mass groups. In the group of patients with residual lesions, analysis of physical parameters showed a significant increase (p < 0.05) in the time necessary for the temperature to rise. In conclusion, this study confirms risk factors of recurrence such as the size of the tumor and emphasizes other factors such as a posttreatment enhanced ring and an increase in the time necessary for the rise in temperature. These factors should be taken into consideration when performing RFA and during follow-up.

  5. The Low-Frequency Environment of the Murchison Widefield Array: Radio-Frequency Interference Analysis and Mitigation

    NASA Astrophysics Data System (ADS)

    Offringa, A. R.; Wayth, R. B.; Hurley-Walker, N.; Kaplan, D. L.; Barry, N.; Beardsley, A. P.; Bell, M. E.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Callingham, J. R.; Cappallo, R. J.; Carroll, P.; Deshpande, A. A.; Dillon, J. S.; Dwarakanath, K. S.; Ewall-Wice, A.; Feng, L.; For, B.-Q.; Gaensler, B. M.; Greenhill, L. J.; Hancock, P.; Hazelton, B. J.; Hewitt, J. N.; Hindson, L.; Jacobs, D. C.; Johnston-Hollitt, M.; Kapińska, A. D.; Kim, H.-S.; Kittiwisit, P.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Morgan, J.; Neben, A. R.; Oberoi, D.; Ord, S. M.; Paul, S.; Pindor, B.; Pober, J. C.; Prabu, T.; Procopio, P.; Riding, J.; Udaya Shankar, N.; Sethi, S.; Srivani, K. S.; Staveley-Smith, L.; Subrahmanyan, R.; Sullivan, I. S.; Tegmark, M.; Thyagarajan, N.; Tingay, S. J.; Trott, C. M.; Webster, R. L.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S.; Zheng, Q.

    2015-03-01

    The Murchison Widefield Array is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations of the future Square Kilometre Array. We describe the automated radio-frequency interference detection strategy implemented for the Murchison Widefield Array, which is based on the aoflagger platform, and present 72-231 MHz radio-frequency interference statistics from 10 observing nights. Radio-frequency interference detection removes 1.1% of the data. Radio-frequency interference from digital TV is observed 3% of the time due to occasional ionospheric or atmospheric propagation. After radio-frequency interference detection and excision, almost all data can be calibrated and imaged without further radio-frequency interference mitigation efforts, including observations within the FM and digital TV bands. The results are compared to a previously published Low-Frequency Array radio-frequency interference survey. The remote location of the Murchison Widefield Array results in a substantially cleaner radio-frequency interference environment compared to Low-Frequency Array's radio environment, but adequate detection of radio-frequency interference is still required before data can be analysed. We include specific recommendations designed to make the Square Kilometre Array more robust to radio-frequency interference, including: the availability of sufficient computing power for radio-frequency interference detection; accounting for radio-frequency interference in the receiver design; a smooth band-pass response; and the capability of radio-frequency interference detection at high time and frequency resolution (second and kHz-scale respectively).

  6. Percutaneous lumbar sympathectomy: A comparison of radiofrequency denervation versus phenol neurolysis

    SciTech Connect

    Haynsworth, R.F. Jr.; Noe, C.E. )

    1991-03-01

    A new percutaneous approach to sympathectomy using radiofrequency denervation has seemed to offer longer duration and less incidence of postsympathetic neuralgia as compared to phenol sympathetic blocks. To compare these techniques, 17 patients underwent either phenol lumbar sympathetic blocks (n = 9) or radiofrequency denervation (n = 8). Duration of sympathetic block was followed by a sweat test and temperature measurements. Results indicate that 89% of patients in the phenol group showed signs of sympathetic blockade after 8 weeks, as compared to 12% in the radiofrequency group (P less than 0.05). Although the incidence of post sympathetic neuralgia appears to be less with radiofrequency denervation, further refinement of needle placement to ensure complete lesioning of the sympathetic chain will be required before the technique can offer advantages over current phenol techniques.

  7. 77 FR 74668 - Compliance Policy Guide; Radiofrequency Identification Feasibility Studies and Pilot Programs for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-17

    ...The Food and Drug Administration (FDA) is extending the expiration date of compliance policy guide (CPG) Sec. 400.210 entitled ``Radiofrequency Identification (RFID) Feasibility Studies and Pilot Programs for Drugs'' to December 31,...

  8. An assessment of the impact of radiofrequency interference on microwave SETI searches

    NASA Technical Reports Server (NTRS)

    Klein, M. J.; Gulkis, S.; Olsen, E. T.; Armstrong, E. F.; Jackson, E. B.

    1992-01-01

    Investigations are carried out at JPL on radiofrequency interferences at very low levels (-130 to -180 dBm) in various bands, especially the 1-2 GHz band. Extrapolation of interferences in the years to come is attempted.

  9. Radiofrequency ablation in an infant with recurrent supraventricular tachycardia and cyanosis

    PubMed Central

    Vora, Amit; Lokhandwala, Yash; Sheth, Chirag; Dalvi, Bharat

    2009-01-01

    We report an unusual presentation of supraventricular tachycardia, in an infant, with cyanosis. The child had atrial septal defect with hypoplastic right ventricle. Radiofrequency ablation was performed in view of drug resistant SVT PMID:20808630

  10. APPLICATION OF A FINITE-DIFFERENCE TECHNIQUE TO THE HUMAN RADIOFREQUENCY DOSIMETRY PROBLEM

    EPA Science Inventory

    A powerful finite difference numerical technique has been applied to the human radiofrequency dosimetry problem. The method possesses inherent advantages over the method of moments approach in that its implementation requires much less computer memory. Consequently, it has the ca...

  11. Getting your signals straight. Comparing radio-frequency ablation and cryoablation for treating cardiac arrhythmias.

    PubMed

    2010-08-01

    Radio-frequency ablation has proven to be an effective method for treating cardiac arrhythmias. However, a newer treatment method called cryoablation is becoming increasingly popular. In this article, we discuss the advantages and disadvantages of each. PMID:21305902

  12. Radio-Frequency Driven Dielectric Heaters for Non-Nuclear Testing in Nuclear Core Development

    NASA Technical Reports Server (NTRS)

    Sims, William Herbert, III (Inventor); Godfroy, Thomas J. (Inventor); Bitteker, Leo (Inventor)

    2006-01-01

    Apparatus and methods are provided through which a radiofrequency dielectric heater has a cylindrical form factor, a variable thermal energy deposition through variations in geometry and composition of a dielectric, and/or has a thermally isolated power input.

  13. Radiofrequency Ablation of Benign Thyroid Nodules and Recurrent Thyroid Cancers: Consensus Statement and Recommendations

    PubMed Central

    Na, Dong Gyu; Lee, Jeong Hyun; Jung, So Lyung; Kim, Ji-hoon; Sung, Jin Yong; Shin, Jung Hee; Kim, Eun-Kyung; Lee, Joon Hyung; Kim, Dong Wook; Park, Jeong Seon; Kim, Kyu Sun; Baek, Seon Mi; Lee, Younghen; Chong, Semin; Sim, Jung Suk; Huh, Jung Yin; Bae, Jae-Ik; Kim, Kyung Tae; Han, Song Yee; Bae, Min Young; Kim, Yoon Suk

    2012-01-01

    Thermal ablation using radiofrequency is a new, minimally invasive modality employed as an alternative to surgery in patients with benign thyroid nodules and recurrent thyroid cancers. The Task Force Committee of the Korean Society of Thyroid Radiology has developed recommendations for the optimal use of radiofrequency ablation for thyroid nodules. These recommendations are based on a comprehensive analysis of the current literature, the results of multicenter studies, and expert consensus. PMID:22438678

  14. Papillary Thyroid Carcinoma Treated with Radiofrequency Ablation in a Patient with Hypertrophic Cardiomyopathy: A Case Report.

    PubMed

    Sun, Jianyi; Liu, Xiaosun; Zhang, Qing; Hong, Yanyun; Song, Bin; Teng, Xiaodong; Yu, Jiren

    2016-01-01

    Standard therapy has not been established for thyroid cancer when a thyroidectomy is contraindicated due to systemic disease. Herein, we reported a patient who had hypertrophic cardiomyopathy and papillary thyroid carcinoma treated by radiofrequency ablation because of inability to tolerate a thyroidectomy. Radiofrequency ablation can be used to treat thyroid cancer when surgery is not feasible, although the long-term outcome needs further observation. PMID:27390548

  15. Papillary Thyroid Carcinoma Treated with Radiofrequency Ablation in a Patient with Hypertrophic Cardiomyopathy: A Case Report

    PubMed Central

    Sun, Jianyi; Liu, Xiaosun; Zhang, Qing; Hong, Yanyun; Song, Bin; Teng, Xiaodong

    2016-01-01

    Standard therapy has not been established for thyroid cancer when a thyroidectomy is contraindicated due to systemic disease. Herein, we reported a patient who had hypertrophic cardiomyopathy and papillary thyroid carcinoma treated by radiofrequency ablation because of inability to tolerate a thyroidectomy. Radiofrequency ablation can be used to treat thyroid cancer when surgery is not feasible, although the long-term outcome needs further observation. PMID:27390548

  16. Percutaneous bipolar radiofrequency thermocoagulation for the treatment of lumbar disc herniation.

    PubMed

    Zeng, Zhenhua; Yan, Min; Dai, Yi; Qiu, Weidong; Deng, Shuo; Gu, Xinzhu

    2016-08-01

    Lumbar disc herniation is usually managed with conservative treatment or surgery. However, conservative therapy seldom yields good results, and surgery is associated with multiple complications. This study aimed to assess bipolar radiofrequency thermocoagulation for the treatment of lumbar disc herniation. A total of 168 patients with lumbar disc herniation suitable for radiofrequency thermocoagulation were enrolled and randomized to monopolar radiofrequency thermocoagulation (control group, n=84) or bipolar radiofrequency thermocoagulation (experimental group, n=84) treatment groups. Ablation sites were targeted under CT scan guidance, and consecutive radiofrequency therapy was used. One and two probes were used for monopolar and bipolar thermocoagulation, respectively. Thermocoagulation was achieved at 50°C, 60°C, and 70°C for 60s each, 80°C for 90s, and 92°C for 100s. Symptoms and complications were evaluated using the modified Macnab criteria and Visual Analog Scale at 7, 30, and 180days postoperatively. At 180days, a significantly higher efficacy rate was obtained in the experimental group compared with control patients (91.6% versus 79.7%, P<0.05). No severe complications were occurred in either group. Targeted ablation via bipolar radiofrequency thermocoagulation is efficient for lumbar disc herniation treatment, and should be further explored for broad clinical application. PMID:27234606

  17. Radiofrequency thermal treatment with chemoradiotherapy for advanced rectal cancer.

    PubMed

    Shoji, Hisanori; Motegi, Masahiko; Osawa, Kiyotaka; Okonogi, Noriyuki; Okazaki, Atsushi; Andou, Yoshitaka; Asao, Takayuki; Kuwano, Hiroyuki; Takahashi, Takeo; Ogoshi, Kyoji

    2016-05-01

    We previously reported that patients with a clinical complete response (CR) following radiofrequency thermal treatment exhibit significantly increased body temperature compared with other groups, whereas patients with a clinical partial response or stable disease depended on the absence or presence of output limiting symptoms. The aim of this study was to evaluate the correlation among treatment response, Hidaka radiofrequency (RF) output classification (HROC: termed by us) and changes in body temperature. From December 2011 to January 2014, 51 consecutive rectal cancer cases were included in this study. All patients underwent 5 RF thermal treatments with concurrent chemoradiation. Patients were classified into three groups based on HROC: with ≤9, 10-16, and ≥17 points, calculated as the sum total points of five treatments. Thirty-three patients received surgery 8 weeks after treatment, and among them, 32 resected specimens were evaluated for histological response. Eighteen patients did not undergo surgery, five because of progressive disease (PD) and 13 refused because of permanent colostomy. We demonstrated that good local control (ypCR + CR + CRPD) was observed in 32.7% of cases in this study. Pathological complete response (ypCR) was observed in 15.7% of the total 51 patients and in 24.2% of the 33 patients who underwent surgery. All ypCR cases had ≥10 points in the HROC, but there were no patients with ypCR among those with ≤9 points in the HROC. Standardization of RF thermal treatment was performed safely, and two types of patients were identified: those without or with increased temperatures, who consequently showed no or some benefit, respectively, for similar RF output thermal treatment. We propose that the HROC is beneficial for evaluating the efficacy of RF thermal treatment with chemoradiation for rectal cancer, and the thermoregulation control mechanism in individual patients may be pivotal in predicting the response to RF

  18. Wireless Chalcogenide Nanoionic-Based Radio-Frequency Switch

    NASA Technical Reports Server (NTRS)

    Nessel, James; Miranda, Felix

    2013-01-01

    A new nonvolatile nanoionic switch is powered and controlled through wireless radio-frequency (RF) transmission. A thin layer of chalcogenide glass doped with a metal ion, such as silver, comprises the operational portion of the switch. For the switch to function, an oxidizable electrode is made positive (anode) with respect to an opposing electrode (cathode) when sufficient bias, typically on the order of a few tenths of a volt or more, is applied. This action causes the metal ions to flow toward the cathode through a coordinated hopping mechanism. At the cathode, a reduction reaction occurs to form a metal deposit. This metal deposit creates a conductive path that bridges the gap between electrodes to turn the switch on. Once this conductive path is formed, no further power is required to maintain it. To reverse this process, the metal deposit is made positive with respect to the original oxidizable electrode, causing the dissolution of the metal bridge thereby turning the switch off. Once the metal deposit has been completely dissolved, the process self-terminates. This switching process features the following attributes. It requires very little to change states (i.e., on and off). Furthermore, no power is required to maintain the states; hence, the state of the switch is nonvolatile. Because of these attributes the integration of a rectenna to provide the necessary power and control is unique to this embodiment. A rectenna, or rectifying antenna, generates DC power from an incident RF signal. The low voltages and power required for the nanoionic switch control are easily generated from this system and provide the switch with a novel capability to be operated and powered from an external wireless device. In one realization, an RF signal of a specific frequency can be used to set the switch into an off state, while another frequency can be used to set the switch to an on state. The wireless, miniaturized, and nomoving- part features of this switch make it

  19. Treatment of Uterine Myomas by Radiofrequency Thermal Ablation

    PubMed Central

    Chen, Ming; Yang, Shujun; Li, Juan; Zhu, Tongyu; Zhao, Xiaoli

    2015-01-01

    Patients’ selection criteria, effectiveness, and safety of radiofrequency thermal ablation (RFTA) therapy for uterine myomas (UM) were assessed using a 10-year retrospective cohort study. From July 2001 to July 2011, a total of 1216 patients treated for UM were divided into 2 groups. Group A consisted of 476 premenopause patients, average age 36.5 ± 8.5 years, average number of myomas 1.7 ± 0.9, and average diameter of myomas 4.5 ± 1.5 cm, and group B consisted of 740 menopause patients, average age 48.5 ± 3.5 years, average number of myomas 2.6 ± 1.3, and average diameter of myomas 5.0 ± 2.5 cm. Average follow-up period was 36.5 ± 11.5 months. At 1, 3, 6, 12, and 24 months after RFTA, average diameters of myomas in group A were 3.8, 3.0, 2.7, 2.4, and 2.2 cm, respectively, and 47.7% (227 of 476) of patients had tumor trace at 12 months after RFTA. In group B, the results were 4.7, 3.7, 3.3, 2.3, and 2.3 cm, respectively, and 58.8% (435 of 740) of patients had tumor trace at 12 months after RFTA. Three months after treatment, myoma volumes were significantly reduced in both the groups (P < .01), and group B had higher rate of tumor trace at 12 months after RFTA than group A (P < .05). Clinical symptoms and health-related quality-of-life outcome (HRQL) were significantly improved after RFTA in both groups and the postoperative recurrence rate of UM was significantly higher in group A at 10.7% (51 of 476) than group B at 2.4% (18 of 740; P < .05). Radiofrequency thermal ablation is an excellent minimally invasive treatment for UM smaller than 5.0 cm in diameter. PMID:25355802

  20. Effects of GSM-like radiofrequency irradiation during the oogenesis and spermiogenesis of Xenopus laevis.

    PubMed

    Boga, Ayper; Emre, Mustafa; Sertdemir, Yasar; Uncu, İbrahim; Binokay, Secil; Demirhan, Osman

    2016-07-01

    We aimed to evaluate the effect of GSM-like radiofrequency electromagnetic radiation (RF-EMR) on the oogenesis, and spermiogenesis of Xenopus laevis, and so the development of the embryos obtained from Normal Females+Normal Males (i.e. "N(F)+N(M)"); Normal Females+RF-exposed Males (i.e. "N(F)+RF(M)"); RF-exposed Female+Normal Male (i.e. "RF(F)+N(M)"); and RF-exposed Female+RF-exposed Male (i.e. "RF(F)+RF(M)". Various, assessments were performed to determine potential teratogenic effects and mortality, body growth and behavior on first generation embryos. After exposing adults frogs of both sexes to 900MHz RF-EMR (at 1.0W/kg) for 8h a day over a 5-week period, the embryos' specific energy absorption rate (SAR) was calculated. In our present study (control group; 2.2% abnormal, 0.0% dead); with the N(F)+RF(M) combination, the long-term exposure of adult males to GSM-like radiation at 900MHz (RF: 2W) for 5 week/8h/day resulted in normal, abnormal and dead embryo ratios of 88.3%, 3.3% and 8.3%, respectively (p<0.001). In the RF(F)+N(M) combination, long-term exposure (5 week/8h/day) of adult females led to normal, abnormal and dead embryo ratios of 76.7%, 11.7%, and 11.7%, respectively (p<0.001). And in the RF(F)+RF(M) combination, long-term exposure (5 week/8h/day) of both adult males and females led to normal, abnormal and dead embryo ratios of 73.3%, 11.7%, and 15%, respectively (p<0.001). With the exception RF(F)+RF(M) group (p<0.001), no significant changes were observed on body growth (lengths) in comparison to the control group. It was also observed that the offspring of female adult Xenopus exposed to RF-EMR during oogenesis exhibited a more aggressive behavior compared to the control group. Cell phones radiation can thus lead to detrimental effects in humans' male and female reproductive cells. PMID:27017260

  1. Noninvasive Radiofrequency Field Destruction of Pancreatic Adenocarcinoma Xenografts Treated with Targeted Gold Nanoparticles

    PubMed Central

    Glazer, Evan S.; Zhu, Cihui; Massey, Katheryn L.; Thompson, C. Shea; Kaluarachchi, Warna D.; Hamir, Amir N.; Curley, Steven A.

    2010-01-01

    Purpose Pancreatic carcinoma is one of the deadliest cancers with few effective treatments. Gold nanoparticles (AuNPs) are potentially therapeutic because of the safety demonstrated thus far and their physio-chemical characteristics. We utilized the astounding heating rates of AuNPs in nonionizing radiofrequency (RF) radiation to investigate human pancreatic xenograft destruction in a murine model. Experimental Design Weekly, Panc-1 and Capan-1 human pancreatic carcinoma xenografts in immunocompromised mice were exposed to an RF field 36 hours after treatment (intraperitoneal) with cetuximab or PAM4 antibody conjugated AuNPs, respectively. Tumor sizes were measured weekly while necrosis and cleaved caspase-3 were investigated with H&E staining and immunofluorescence, respectively. In addition, AuNP internalization and cytotoxicity were investigated in vitro with confocal microscopy and flow cytometry, respectively. Results Panc-1 cells demonstrated increased apoptosis with decreased viability after treatment with cetuximab conjugated AuNPs and RF field exposure (p = 0.00005). Differences in xenograft volumes were observed within 2 weeks of initiating therapy. Cetuximab-conjugated and PAM4-conjugated AuNPs demonstrated RF field-induced destruction of Panc-1 and Capan-1 pancreatic carcinoma xenografts after six weeks of weekly treatment (p = 0.004 and p = 0.035, respectively). There was no evidence of injury to murine organs. Cleaved caspase-3 and necrosis were both increased in treated tumors. Conclusions This study demonstrates a potentially novel cancer therapy by non-invasively inducing intracellular hyperthermia with targeted AuNPs in an RF field. While the therapy is dependent on the specificity of the targeting antibody, normal tissues were without toxicity despite systemic therapy and whole body RF field exposure. PMID:21138869

  2. Thermal Ablation of Lung Tissue: In Vivo Experimental Comparison of Microwave and Radiofrequency

    SciTech Connect

    Crocetti, Laura Bozzi, Elena; Faviana, Pinuccia; Cioni, Dania; Della Pina, Clotilde; Sbrana, Alberto; Fontanini, Gabriella; Lencioni, Riccardo

    2010-08-15

    This study was designed to compare feasibility, safety, and effectiveness of microwave (MW) ablation versus radiofrequency (RF) ablation of lung tissue in a rabbit model. Twenty New Zealand White rabbits were submitted to MW (n = 10, group A) or RF ablation (n = 10, group B). The procedures were performed with a prototype MW ablation device with a 1.6-cm radiating section antenna (Valleylab MW Ablation System) and with a 2-cm exposed-tip RF electrode (Cool-tip RF Ablation System). At immediate computed tomography increase in density, maximum diameters (D1-D3) of ablation zones were measured and ablation volume was calculated. Histopathologic assessment was performed 3 and 7 days after the procedure. Technical success was achieved in nine of 10 rabbits in each group. One death occurred in group B. Complications included pneumothorax (group A, n = 4; group B, n = 4), abscess (group A, n = 1; group B, n = 1), and thoracic wall burn (group A, n = 4). No significant differences were demonstrated in attenuation increase (P = 0.73), dimensions (P = 0.28, 0.86, 0.06, respectively, comparing D1-D3) and volume (P = 0.17). At histopathology, ablation zones were similar, with septal necrosis, edema, hemorrhage, and peripheral lymphocytic infiltrate. Complete thrombosis of more than 90% of vessels up to 2 mm in diameter was depicted at the periphery of the ablation zone in group A specimens. In group B specimens, complete thrombosis was depicted in 20% of vessels. Feasibility and safety of MW and RF ablation are similar in a lung rabbit model. MW ablation produces a greater damage to peripheral small vessels inducing thrombosis.

  3. Field orientation effects during 5. 6-GHz radiofrequency irradiation of rats

    SciTech Connect

    Frei, M.R.; Jauchem, J.R.; Price, D.L.; Padilla, J.M. )

    1990-12-01

    Ketamine-anesthetized Sprague-Dawley rats were exposed in E and H orientations (long axis parallel to electric and magnetic fields, respectively) to far-field 5.6-GHz continuous-wave radio-frequency radiation (RFR). Power densities were used that resulted in equivalent whole-body average specific absorption rates of 14 W/kg in both orientations (90 mW/cm2 for E and 66 mW/cm2 for H). Irradiation was conducted to increase colonic temperature by 1 degree C (from 38.5 to 39.5 degrees C). During experimentation, arterial blood pressure and respiratory rate and colonic, tympanic, left and right subcutaneous (sides toward and away from RFR source), and tail temperatures were continuously recorded. Results showed no significant difference in the times required to cause a 1 degree C increase or to recover to the initial temperature when irradiation was stopped. Significant differences between E- and H-orientation exposure were seen in the patterns of localized heating. The tail and left subcutaneous temperature increases were significantly greater during E-orientation exposure, the tympanic site showed no difference, and the right subcutaneous temperature increase was significantly greater during H-orientation exposure. Under both exposure conditions, heart rate and mean arterial blood pressure significantly increased during irradiation; however, there were no significant differences between E and H orientation responses. These findings at 5.6 GHz are in contrast to the significant cardiovascular response differences between E- and H-orientation exposure noted during a previous study of irradiation at 2.45 GHz.

  4. Radiofrequency electromagnetic field exposure and non-specific symptoms of ill health: A systematic review

    SciTech Connect

    Roeoesli, Martin

    2008-06-15

    This article is a systematic review of whether everyday exposure to radiofrequency electromagnetic field (RF-EMF) causes symptoms, and whether some individuals are able to detect low-level RF-EMF (below the ICNIRP [International Commission on Non-Ionizing Radiation Protection] guidelines). Peer-reviewed articles published before August 2007 were identified by means of a systematic literature search. Meta-analytic techniques were used to pool the results from studies investigating the ability to discriminate active from sham RF-EMF exposure. RF-EMF discrimination was investigated in seven studies including a total of 182 self-declared electromagnetic hypersensitive (EHS) individuals and 332 non-EHS individuals. The pooled correct field detection rate was 4.2% better than expected by chance (95% CI: -2.1 to 10.5). There was no evidence that EHS individuals could detect presence or absence of RF-EMF better than other persons. There was little evidence that short-term exposure to a mobile phone or base station causes symptoms based on the results of eight randomized trials investigating 194 EHS and 346 non-EHS individuals in a laboratory. Some of the trials provided evidence for the occurrence of nocebo effects. In population based studies an association between symptoms and exposure to RF-EMF in the everyday environment was repeatedly observed. This review showed that the large majority of individuals who claims to be able to detect low level RF-EMF are not able to do so under double-blind conditions. If such individuals exist, they represent a small minority and have not been identified yet. The available observational studies do not allow differentiating between biophysical from EMF and nocebo effects.

  5. Metabolic and vasomotor responses of rhesus monkeys exposed to 225-MHz radiofrequency energy

    SciTech Connect

    Lotz, W.G.; Saxton, J.L.

    1987-01-01

    A previous study showed a substantial increase in the colonic temperature of rhesus monkeys (Macaca mulatta) exposed to radio-frequency (RF) fields at a frequency near whole-body resonance and specific absorption rates (SAR) of 2 to 3 W/kg. The present experiments were conducted to determine the metabolic and vasomotor responses during exposures to similar RF fields. Five adult male rhesus monkeys were exposed to 225-MHz radiation (E orientation) in an anechoic chamber. The monkeys were irradiated at two carefully-controlled ambient temperatures, either cool (20 C) or thermoneutral (26 C). Power densities ranged from 0 (sham) to 10.0 mW/sq cm with an average whole-body SAR of 0.285 (W/kg)/(mW/sq cm). Two experimental protocols were used, each of which began with a 120-min preexposure equilibration period. Then, one protocol involved repetitive 10-min RF exposures at successively higher power densities with a recovery period between exposures. In the second protocol, a 120-min RF exposure permitted the measurement of steady-state thermoregulatory responses. Metabolic and vasomotor adjustments in the rhesus monkey exposed to 225 MHz occurred during brief or sustained exposures at SARs at or above 1.4 W/kg. Metabolic and vasomotor responses were coordinated effectively to produce a stable deep-body temperature. The results show that the thermoregulatory response of the rhesus monkey to an RF exposure at a resonant frequency limits storage of heat in the body. However, substantial increases in colonic temperature were not prevented by such responses, even in a cool environment.

  6. Metabolic and vasomotor responses of rhesus monkeys exposed to 225-MHz radiofrequency energy. [Macaca mulatta

    SciTech Connect

    Lotz, W.G.; Saxton, J.L.

    1987-01-01

    A previous study showed a substantial increase in the colonic temperature of rhesus monkeys (Macaca mulatta) exposed to radiofrequency (RF) fields at a frequency near whole-body resonance and specific absorption rates (SAR) of 2-3 W/kg. The present experiments were conducted to determine the metabolic and vasomotor responses during exposures to similar RF fields. We exposed five adult male rhesus monkeys to 225 MHz radiation (E orientation) in an anechoic chamber. Oxygen consumption and carbon dioxide production were measured before, during, and after RF exposure. Colonic, tail and leg skin temperatures were continuously monitored with RF-nonperturbing probes. The monkeys were irradiated at two carefully-controlled ambient temperatures, either cool (20 degrees C) or thermoneutral (26 degrees C). Power densities ranged from 0 (sham) to 10.0 mW/cm2 with an average whole-body SAR of 0.285 (W/kg)/(mW/cm2). We used two experimental protocols, each of which began with a 120-min pre-exposure equilibration period. One protocol involved repetitive 10-min RF exposures at successively higher power densities with a recovery period between exposures. In the second protocol, a 120-min RF exposure permitted the measurement of steady-state thermoregulatory responses. Metabolic and vasomotor adjustments in the rhesus monkey exposed to 225 MHz occurred during brief or sustained exposures at SARs at or above 1.4 W/kg. The SAR required to produce a given response varied with ambient temperature. Metabolic and vasomotor responses were coordinated effectively to produce a stable deep body temperature. The results show that the thermoregulatory response of the rhesus monkey to an RF exposure at a resonant frequency limits storage of heat in the body. However, substantial increases in colonic temperature were not prevented by such responses, even in a cool environment.

  7. Radiofrequency field-induced thermal cytotoxicity in cancer cells treated with fluorescent nanoparticles

    PubMed Central

    Glazer, Evan S.; Curley, Steven A.

    2010-01-01

    Background Non-ionizing radiation, such as radiofrequency (RF) field and near infrared laser, induces thermal cytotoxicity in cancer cells treated with gold nanoparticles (AuNP). Quantum dots (QD) are fluorescent semiconducting nanoparticles that we hypothesize will induce similar injury following RF field irradiation. Methods AuNP and two types of QD (cadmium-selenide and indium-gallium-phosphide) conjugated to cetuximab (C225), a monoclonal antibody against human epidermal growth factor receptor (EGFR-1), demonstrated concentration-dependent heating in a RF field. We investigated the effect of RF field exposure after targeted nanoparticle treatment in a co-culture of two human cancer cell lines that have differential EGFR-1 expression (a high expressing pancreatic carcinoma, Panc-1, and a low expressing breast carcinoma, Cama-1). Results RF exposed Panc-1 or Cama-1 cells not containing AuNP or QD had a viability greater than 92%. The viability of Panc-1 cells exposed to the RF field after treatment with 50 nM Au-C225 was 39.4% ± 8.3% without injury to bystander Cama-1 cells (viability was 93.7% ± 1.0%, p ~ 0.0006). Panc-1 cells treated with targeted Cd-Se QD were only 47.5% viable after RF field exposure (p < 0.0001 compared to RF only Panc-1 control cells). Targeted InGaP QD decreased Panc-1 viability to 58.2% ± 3.4% after RF field exposure (p ~ 0.0004 compared to Cama-1 and Panc-1 controls). Conclusion We selectively induced RF field cytotoxicity in Panc-1 cells without injury to bystander Cama-1 cells utilizing EGFR-1 targeted nanoparticles, and demonstrated an interesting bifunctionality of fluorescent nanoparticles as agents for both cancer cell imaging and treatment. PMID:20564640

  8. Microsimulation Model Predicts Survival Benefit of Radiofrequency Ablation and Stereotactic Body Radiotherapy Versus Radiotherapy for Treating Inoperable Stage I Non–Small Cell Lung Cancer

    PubMed Central

    Tramontano, Angela C.; Cipriano, Lauren E.; Kong, Chung Yin; Shepard, Jo-Anne O.; Lanuti, Michael; Gazelle, G. Scott; McMahon, Pamela M.

    2013-01-01

    OBJECTIVE A subset of patients with stage IA and IB non–small cell lung cancer (NSCLC) is ineligible for surgical resection and undergoes radiation therapy. Radiofrequency ablation (RFA) and stereotactic body radiotherapy are newer potentially attractive alternative therapies. MATERIALS AND METHODS We added RFA and stereotactic body radiotherapy treatment modules to a microsimulation model that simulates lung cancer’s natural history, detection, and treatment. Natural history parameters were previously estimated via calibration against tumor registry data and cohort studies; the model was validated with screening study and cohort data. RFA model parameters were calibrated against 2-year survival from the Radiofrequency Ablation of Pulmonary Tumor Response Evaluation (RAPTURE) study, and stereotactic body radiotherapy model parameters were calibrated against 3-year survival from a phase 2 prospective trial. We simulated lifetime histories of identical patients with early-stage NSCLC who were ineligible for resection, who were treated with radiation therapy, RFA, or stereotactic body radiotherapy under a range of scenarios. From 5,000,000 simulated individuals, we selected a cohort of patients with stage I medically inoperable cancer for analysis (n = 2056 per treatment scenario). Main outcomes were life expectancy gains. RESULTS RFA or stereotactic body radiotherapy treatment in patients with peripheral stage IA or IB NSCLC who were nonoperative candidates resulted in life expectancy gains of 1.71 and 1.46 life-years, respectively, compared with universal radiation therapy. A strategy where patients with central tumors underwent stereotactic body radiotherapy and those with peripheral tumors underwent RFA resulted in a gain of 2.02 life-years compared with universal radiation therapy. Findings were robust with respect to changes in model parameters. CONCLUSION Microsimulation modeling results suggest that RFA and stereotactic body radiotherapy could provide life

  9. Heat Sink Effect on Tumor Ablation Characteristics as Observed in Monopolar Radiofrequency, Bipolar Radiofrequency, and Microwave, Using Ex Vivo Calf Liver Model

    PubMed Central

    Pillai, Krishna; Akhter, Javid; Chua, Terence C.; Shehata, Mena; Alzahrani, Nayef; Al-Alem, Issan; Morris, David L.

    2015-01-01

    Abstract Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices. With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored. With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres. Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected. Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5. MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink. PMID:25738477

  10. Heat sink effect on tumor ablation characteristics as observed in monopolar radiofrequency, bipolar radiofrequency, and microwave, using ex vivo calf liver model.

    PubMed

    Pillai, Krishna; Akhter, Javid; Chua, Terence C; Shehata, Mena; Alzahrani, Nayef; Al-Alem, Issan; Morris, David L

    2015-03-01

    Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink. PMID:25738477

  11. Supercomputer Simulation of Radio-frequency Hepatic Tumor Ablation

    NASA Astrophysics Data System (ADS)

    Kosturski, N.; Margenov, S.

    2010-11-01

    We simulate the thermal and electrical processes, involved in the radio-frequency (RF) ablation procedure. The mathematical model consists of two parts—electrical and thermal. The energy from the applied AC voltage is determined first, by solving the Laplace equation to find the potential distribution. After that, the electric field intensity and the current density are directly calculated. Finally, the heat transfer equation is solved to determine the temperature distribution. Heat loss due to blood perfusion is also accounted for. The representation of the computational domain is based on a voxel mesh. Both partial differential equations are discretized in space via linear conforming FEM. After the space discretization, the backward Euler scheme is used for the time stepping. Large-scale linear systems arise from the FEM discretization. Moreover, they are ill-conditioned, due to the strong coefficient jumps and the complex geometry of the problem. Therefore, efficient parallel solution methods are required. The developed parallel solver is based on the preconditioned conjugate gradient (PCG) method. As a preconditioner, we use BoomerAMG—a parallel algebraic multigrid implementation from the package Hypre, developed in LLNL, Livermore. Parallel numerical tests, performed on the IBM Blue Gene/P massively parallel computer are presented.

  12. GPU enabled kinetic effects in radio-frequency heating simulation

    NASA Astrophysics Data System (ADS)

    Green, David; RF-SciDAC Collaboration

    2015-11-01

    In previous work we have demonstrated the iterative addition of parallel kinetic effects to finite-difference frequency-domain simulation of radio-frequency (RF) wave propagation in fusion relevant plasmas. Such iterative addition in configuration space bypasses several of the difficulties with traditional spectral methods for kinetic RF simulation when applied to problems that exhibit non-periodic geometries. Furthermore, the direct numerical integration of particle trajectories in real magnetic field geometries removes violations of the stationary phase approximation inherent in the spectral approach. Here we extend this method to include perpendicular kinetics by relying on the massively parallel capability of GPUs to enable resolution of 3 velocity-space dimensions. We present results for a mode converted ion Bernstein wave scenario in 1-space plus 3-velocity dimensions case relevant to fusion plasmas. This research used resources of the OLCF at ORNL, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.

  13. [Ablation using radiofrequency in the treatment of ventricular tachycardia].

    PubMed

    Cordero Cabra, J A; Iturralde Torres, P; Lara Vaca, S; Colín Lizalde, L; Kershenovich, S; Carvajal, A; González Hermosillo, J A

    1996-01-01

    We performed radiofrequency catheter ablation in 14 consecutive patients with Ventricular Tachycardia (VT) 10 of which had healthy hearts, one patient with ischemic heart disease, one with arrhythmogenic dysplasia, one with dilated cardiomyopathy, and one with congenital heart disease. The localization of the VT was: 10 in the left posterior fascicular region, 3 in the right ventricular outflow tract (RVOT), and one patient with ischemic heart disease with the substrate in the left ventricular apex. All of them with VT refractory to pharmacological management, using an average of 2.7 drugs per patient. After all patients underwent Electrophysiological Study (EPS), an intracavitary mapping was performed, in order to locate the arrhythmogenic substrate. Later on, the RF ablation was performed, delivering an average of 15 pulses, using 40 Watts, and an average time of 25 sec. per pulse. The procedure was successful in 60% of the fascicular VT, with a 16% of recurrence; 100% of success with those originated in the RVOT with no recurrence; in the ischemic patient we achieved primary success, but with recurrence, a second session was successful with no recurrence up to date. No major complications occurred in this group. Those patients which showed no success required the use of antiarrhythmic drugs. The total success of the series is 71.4% with 10% recurrence, and no mortality. PMID:8967816

  14. Wavelet Domain Radiofrequency Pulse Design Applied to Magnetic Resonance Imaging

    PubMed Central

    Huettner, Andrew M.; Mickevicius, Nikolai J.; Ersoz, Ali; Koch, Kevin M.; Muftuler, L. Tugan; Nencka, Andrew S.

    2015-01-01

    A new method for designing radiofrequency (RF) pulses with numerical optimization in the wavelet domain is presented. Numerical optimization may yield solutions that might otherwise have not been discovered with analytic techniques alone. Further, processing in the wavelet domain reduces the number of unknowns through compression properties inherent in wavelet transforms, providing a more tractable optimization problem. This algorithm is demonstrated with simultaneous multi-slice (SMS) spin echo refocusing pulses because reduced peak RF power is necessary for SMS diffusion imaging with high acceleration factors. An iterative, nonlinear, constrained numerical minimization algorithm was developed to generate an optimized RF pulse waveform. Wavelet domain coefficients were modulated while iteratively running a Bloch equation simulator to generate the intermediate slice profile of the net magnetization. The algorithm minimizes the L2-norm of the slice profile with additional terms to penalize rejection band ripple and maximize the net transverse magnetization across each slice. Simulations and human brain imaging were used to demonstrate a new RF pulse design that yields an optimized slice profile and reduced peak energy deposition when applied to a multiband single-shot echo planar diffusion acquisition. This method may be used to optimize factors such as magnitude and phase spectral profiles and peak RF pulse power for multiband simultaneous multi-slice (SMS) acquisitions. Wavelet-based RF pulse optimization provides a useful design method to achieve a pulse waveform with beneficial amplitude reduction while preserving appropriate magnetization response for magnetic resonance imaging. PMID:26517262

  15. Laser ablation loading of a radiofrequency ion trap

    NASA Astrophysics Data System (ADS)

    Zimmermann, K.; Okhapkin, M. V.; Herrera-Sancho, O. A.; Peik, E.

    2012-06-01

    The production of ions via laser ablation for the loading of radiofrequency (RF) ion traps is investigated using a nitrogen laser with a maximum pulse energy of 0.17 mJ and a peak intensity of about 250 MW/cm2. A time-of-flight mass spectrometer is used to measure the ion yield and the distribution of the charge states. Singly charged ions of elements that are presently considered for the use in optical clocks or quantum logic applications could be produced from metallic samples at a rate of the order of magnitude 105 ions per pulse. A linear Paul trap was loaded with Th+ ions produced by laser ablation. An overall ion production and trapping efficiency of 10-7 to 10-6 was attained. For ions injected individually, a dependence of the capture probability on the phase of the RF field has been predicted. In the experiment this was not observed, presumably because of collective effects within the ablation plume.

  16. Mechanical properties of niobium radio-frequency cavities

    SciTech Connect

    Ciovati, Gianluigi; Dhakal, Pashupati; Matalevich, Joseph R.; Myneni, Ganapati Rao; Schmidt, A.; Iversen, J.; Matheisen, A.; Singer, W.

    2015-07-02

    Radio-frequency cavities made of bulk niobium are one of the components used in modern particle accelerators. The mechanical stability is an important aspect of cavity design, which typically relies on finite-element analysis simulations using material properties from tensile tests on sample. This contribution presents the results of strain and resonant frequency measurements as a function of a uniform pressure up to 722 kPa, applied to single-cell niobium cavities with different crystallographic structure, purity and treatments. In addition, burst tests of high-purity multi-cell cavities with different crystallographic structure have been conducted up to the tensile strength of the material. Finite-element analysis of the single-cell cavity geometry is in good agreement with the observed behavior in the elastic regime assuming a Young's modulus value of 88.5 GPa and a Poisson's ratio of 0.4, regardless of crystallographic structure, purity or treatment. However, the measured yield strength and tensile strength depend on crystallographic structure, material purity and treatment. In particular, the results from this study show that the mechanical properties of niobium cavities with large crystals are comparable to those of cavities made of fine-grain niobium.

  17. Radio-frequency capacitance spectroscopy of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Frake, James C.; Kano, Shinya; Ciccarelli, Chiara; Griffiths, Jonathan; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka; Smith, Charles G.; Buitelaar, Mark R.

    2015-06-01

    Recent years have seen great progress in our understanding of the electronic properties of nanomaterials in which at least one dimension measures less than 100 nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge as even state-of-the-art nanofabrication techniques such as electron-beam lithography have a resolution of a few nm at best. Here we present a fabrication and measurement technique that allows high sensitivity and high bandwidth readout of discrete quantum states of metallic nanoparticles which does not require nm resolution or precision. This is achieved by coupling the nanoparticles to resonant electrical circuits and measurement of the phase of a reflected radio-frequency signal. This requires only a single tunnel contact to the nanoparticles thus simplifying device fabrication and improving yield and reliability. The technique is demonstrated by measurements on 2.7 nm thiol coated gold nanoparticles which are shown to be in excellent quantitative agreement with theory.

  18. Evaporative cooling in a radio-frequency trap

    SciTech Connect

    Garrido Alzar, Carlos L.; Perrin, Helene; Lorent, Vincent; Garraway, Barry M.

    2006-11-15

    A theoretical investigation for implementing a scheme of forced evaporative cooling in radio-frequency (rf) adiabatic potentials is presented. Supposing the atoms to be trapped in a combination of a dc magnetic field and a rf field at frequency {omega}{sub 1}, the cooling procedure is facilitated using a second rf source at frequency {omega}{sub 2}. This second rf field produces a controlled coupling between the spin states dressed by {omega}{sub 1}. The evaporation is then possible in a pulsed or continuous mode. In the pulsed case, atoms with a given energy are transferred into untrapped dressed states by abruptly switching off the {omega}{sub 2} coupling. In the continuous case, it is possible for energetic atoms to adiabatically follow the doubly dressed states and escape out of the trap. Our results also show that when {omega}{sub 1} and {omega}{sub 2} are separated by at least the Rabi frequency associated with {omega}{sub 1}, additional evaporation zones appear which can make this process more efficient.

  19. Dispersion-engineered multicore fibers for distributed radiofrequency signal processing.

    PubMed

    García, Sergi; Gasulla, Ivana

    2016-09-01

    We report a trench-assisted heterogeneous multicore fiber optimized in terms of higher-order dispersion and crosstalk for radiofrequency true time delay operation. The analysis of the influence of the core refractive index profile on the dispersion slope and effective index reveals a tradeoff between the behavior of the crosstalk against fiber curvatures and the linearity of the propagation group delay. We investigate the optimization of the multicore fiber in the framework of this tradeoff and present a design that features a group delay relative error below 5% for an optical wavelength range up to 100 nm and a crosstalk level below -80 dB for bending radii larger than 103 mm. The performance of the true time delay line is validated in the context of microwave signal filtering and optical beamforming for phased array antennas. This work opens the way towards the development of compact fiber-integrated solutions that enable the implementation of a variety of distributed signal processing functionalities that will be key in future fiber-wireless communications networks and systems. PMID:27607668

  20. Radio-frequency energy harvesting for wearable sensors.

    PubMed

    Borges, Luís M; Chávez-Santiago, Raul; Barroca, Norberto; Velez, Fernando José; Balasingham, Ilangko

    2015-02-01

    The use of wearable biomedical sensors for the continuous monitoring of physiological signals will facilitate the involvement of the patients in the prevention and management of chronic diseases. The fabrication of small biomedical sensors transmitting physiological data wirelessly is possible as a result of the tremendous advances in ultra-low power electronics and radio communications. However, the widespread adoption of these devices depends very much on their ability to operate for long periods of time without the need to frequently change, recharge or even use batteries. In this context, energy harvesting (EH) is the disruptive technology that can pave the road towards the massive utilisation of wireless wearable sensors for patient self-monitoring and daily healthcare. Radio-frequency (RF) transmissions from commercial telecommunication networks represent reliable ambient energy that can be harvested as they are ubiquitous in urban and suburban areas. The state-of-the-art in RF EH for wearable biomedical sensors specifically targeting the global system of mobile 900/1800 cellular and 700 MHz digital terrestrial television networks as ambient RF energy sources are showcased. Furthermore, guidelines for the choice of the number of stages for the RF energy harvester are presented, depending on the requirements from the embedded system to power supply, which is useful for other researchers that work in the same area. The present authors' recent advances towards the development of an efficient RF energy harvester and storing system are presented and thoroughly discussed too. PMID:26609400

  1. Development of A Pulse Radio-Frequency Plasma Jet

    NASA Astrophysics Data System (ADS)

    Wang, Shou-Guo; Zhao, Ling-Li; Yang, Jing-Hua

    2013-09-01

    A small pulse plasma jet was driven by new developed radio-frequency (RF) power supply of 6.78 MHz. In contrast to the conventional RF 13.56 MHz atmospheric pressure plasma jet (APPJ), the power supply was highly simplified by eliminating the matching unit of the RF power supply and using a new circuit, moreover, a pulse controller was added to the circuit to produce the pulse discharge. The plasma jet was operated in a capacitively coupled manner and exhibited low power requirement of 5 W at atmospheric pressure using argon as a carrier gas. The pulse plasma plume temperature remained at less than 45 °C for an extended period of operation without using water to cool the electrodes. Optical emission spectrum measured at a wide range of 200-1000 nm indicated various excited species which were helpful in applying the plasma jet for surface sterilization to human skin or other sensitive materials. Institude of Plasma Physics, Chinese Academy of Science, Hefei, China.

  2. A comparative study of radiofrequency antennas for Helicon plasma sources

    NASA Astrophysics Data System (ADS)

    Melazzi, D.; Lancellotti, V.

    2015-04-01

    Since Helicon plasma sources can efficiently couple power and generate high-density plasma, they have received interest also as spacecraft propulsive devices, among other applications. In order to maximize the power deposited into the plasma, it is necessary to assess the performance of the radiofrequency (RF) antenna that drives the discharge, as typical plasma parameters (e.g. the density) are varied. For this reason, we have conducted a comparative analysis of three Helicon sources which feature different RF antennas, namely, the single-loop, the Nagoya type-III and the fractional helix. These antennas are compared in terms of input impedance and induced current density; in particular, the real part of the impedance constitutes a measure of the antenna ability to couple power into the plasma. The results presented in this work have been obtained through a full-wave approach which (being hinged on the numerical solution of a system of integral equations) allows computing the antenna current and impedance self-consistently. Our findings indicate that certain combinations of plasma parameters can indeed maximize the real part of the input impedance and, thus, the deposited power, and that one of the three antennas analyzed performs best for a given plasma. Furthermore, unlike other strategies which rely on approximate antenna models, our approach enables us to reveal that the antenna current density is not spatially uniform, and that a correlation exists between the plasma parameters and the spatial distribution of the current density.

  3. Radiofrequency signal affects alpha band in resting electroencephalogram.

    PubMed

    Ghosn, Rania; Yahia-Cherif, Lydia; Hugueville, Laurent; Ducorps, Antoine; Lemaréchal, Jean-Didier; Thuróczy, György; de Seze, René; Selmaoui, Brahim

    2015-04-01

    The aim of the present work was to investigate the effects of the radiofrequency (RF) electromagnetic fields (EMFs) on human resting EEG with a control of some parameters that are known to affect alpha band, such as electrode impedance, salivary cortisol, and caffeine. Eyes-open and eyes-closed resting EEG data were recorded in 26 healthy young subjects under two conditions: sham exposure and real exposure in double-blind, counterbalanced, crossover design. Spectral power of EEG rhythms was calculated for the alpha band (8-12 Hz). Saliva samples were collected before and after the study. Salivary cortisol and caffeine were assessed by ELISA and HPLC, respectively. The electrode impedance was recorded at the beginning of each run. Compared with the sham session, the exposure session showed a statistically significant (P < 0.0001) decrease of the alpha band spectral power during closed-eyes condition. This effect persisted in the postexposure session (P < 0.0001). No significant changes were detected in electrode impedance, salivary cortisol, and caffeine in the sham session compared with the exposure one. These results suggest that GSM-EMFs of a mobile phone affect the alpha band within spectral power of resting human EEG. PMID:25695646

  4. Radiofrequency signal affects alpha band in resting electroencephalogram

    PubMed Central

    Ghosn, Rania; Yahia-Cherif, Lydia; Hugueville, Laurent; Ducorps, Antoine; Lemaréchal, Jean-Didier; Thuróczy, György; de Seze, René

    2015-01-01

    The aim of the present work was to investigate the effects of the radiofrequency (RF) electromagnetic fields (EMFs) on human resting EEG with a control of some parameters that are known to affect alpha band, such as electrode impedance, salivary cortisol, and caffeine. Eyes-open and eyes-closed resting EEG data were recorded in 26 healthy young subjects under two conditions: sham exposure and real exposure in double-blind, counterbalanced, crossover design. Spectral power of EEG rhythms was calculated for the alpha band (8–12 Hz). Saliva samples were collected before and after the study. Salivary cortisol and caffeine were assessed by ELISA and HPLC, respectively. The electrode impedance was recorded at the beginning of each run. Compared with the sham session, the exposure session showed a statistically significant (P < 0.0001) decrease of the alpha band spectral power during closed-eyes condition. This effect persisted in the postexposure session (P < 0.0001). No significant changes were detected in electrode impedance, salivary cortisol, and caffeine in the sham session compared with the exposure one. These results suggest that GSM-EMFs of a mobile phone affect the alpha band within spectral power of resting human EEG. PMID:25695646

  5. Software-assisted post-interventional assessment of radiofrequency ablation

    NASA Astrophysics Data System (ADS)

    Rieder, Christian; Geisler, Benjamin; Bruners, Philipp; Isfort, Peter; Na, Hong-Sik; Mahnken, Andreas H.; Hahn, Horst K.

    2014-03-01

    Radiofrequency ablation (RFA) is becoming a standard procedure for minimally invasive tumor treatment in clinical practice. Due to its common technical procedure, low complication rate, and low cost, RFA has become an alternative to surgical resection in the liver. To evaluate the therapy success of RFA, thorough follow-up imaging is essential. Conventionally, shape, size, and position of tumor and coagulation are visually compared in a side-by-side manner using pre- and post-interventional images. To objectify the verification of the treatment success, a novel software assistant allowing for fast and accurate comparison of tumor and coagulation is proposed. In this work, the clinical value of the proposed assessment software is evaluated. In a retrospective clinical study, 39 cases of hepatic tumor ablation are evaluated using the prototype software and conventional image comparison by four radiologists with different levels of experience. The cases are randomized and evaluated in two sessions to avoid any recall-bias. Self-confidence of correct diagnosis (local recurrence vs. no local recurrence) on a six-point scale is given for each case by the radiologists. Sensitivity, specificity, positive and negative predictive values as well as receiver operating curves are calculated for both methods. It is shown that the software-assisted method allows physicians to correctly identify local tumor recurrence with a higher percentage than the conventional method (sensitivity: 0.6 vs. 0.35), whereas the percentage of correctly identified successful ablations is slightly reduced (specificity: 0.83 vs. 0.89).

  6. A review of the general aspects of radiofrequency ablation.

    PubMed

    Ni, Y; Mulier, S; Miao, Y; Michel, L; Marchal, G

    2005-01-01

    As an alternative to standard surgical resection for the treatment of malignant tumors, radiofrequency ablation (RFA) has rapidly evolved into the most popular minimally invasive therapy. To help readers gain the relevant background knowledge and to better understand the other reviews in this Feature Section on the clinical applications of RFA in different abdominal organs, the present report covers the general aspects of RFA. After an introduction, we present a simple definition of the energy applied during RFA, a brief historical review of its technical evolution, and an explanation of the mechanism of action of RFA. These basic discussions are substantiated with descriptions of RFA equipment including those commercially available and those under preclinical development. The size and geometry of induced lesions in relation to RFA efficacy and side effects are discussed. The unique pathophysiologic process of thermal tissue damage and the corresponding histomorphologic manifestations after RFA are detailed and cross-referenced with the findings in the current literature. The crucial role of imaging technology during and after RFA is also addressed, including some promising new developments. This report finishes with a summary of the key messages and a perspective on further technologic refinements and identifies some specific priorities. PMID:15776302

  7. [RADIOFREQUENCY ABLATION FOR THE TREATMENT OF VARICOSE VEINS].

    PubMed

    Sugiyama, Satoru; Miyade, Yoshio; Inaki, Yasuhiko

    2015-05-01

    Significant advances in the endovenous technique for treating incompetent saphenous veins could change the surgical strategy in patients with varicose veins. Radiofrequency ablation (RFA) was approved as a new technique for the treatment of varicose veins in Japan in June 2014. In RFA, the ablation temperature is controlled by a sensor at the upper end of the catheter. The vein wall is heated with stable conductive power of 120 degrees C, resulting in endothelial denudation. The RFA method was approved in 1998 in Europe and in 1999 in the USA. The ClosurePLUS catheter was developed in 2003 and ClosureFAST in 2006. High occlusion rates and lower postoperative complication rates were reported with ClosureFAST than with ClosurePLUS. It is expected that this new ablation technique will control saphenous vein reflux with less pain and less ecchymosis after surgery. The treatment of varicose veins is less invasive with RFA devices and will become widely accepted as an alternative to conventional surgery for varicose veins in Japan. PMID:26281655

  8. Mechanical properties of niobium radio-frequency cavities

    DOE PAGESBeta

    Ciovati, Gianluigi; Dhakal, Pashupati; Matalevich, Joseph R.; Myneni, Ganapati Rao; Schmidt, A.; Iversen, J.; Matheisen, A.; Singer, W.

    2015-07-02

    Radio-frequency cavities made of bulk niobium are one of the components used in modern particle accelerators. The mechanical stability is an important aspect of cavity design, which typically relies on finite-element analysis simulations using material properties from tensile tests on sample. This contribution presents the results of strain and resonant frequency measurements as a function of a uniform pressure up to 722 kPa, applied to single-cell niobium cavities with different crystallographic structure, purity and treatments. In addition, burst tests of high-purity multi-cell cavities with different crystallographic structure have been conducted up to the tensile strength of the material. Finite-element analysismore » of the single-cell cavity geometry is in good agreement with the observed behavior in the elastic regime assuming a Young's modulus value of 88.5 GPa and a Poisson's ratio of 0.4, regardless of crystallographic structure, purity or treatment. However, the measured yield strength and tensile strength depend on crystallographic structure, material purity and treatment. In particular, the results from this study show that the mechanical properties of niobium cavities with large crystals are comparable to those of cavities made of fine-grain niobium.« less

  9. Recent progress in radiofrequency ablation therapy for hepatocellular carcinoma.

    PubMed

    Ikeda, Kenji; Osaki, Yukio; Nakanishi, Hiroyuki; Nasu, Akihiro; Kawamura, Yusuke; Jyoko, Koji; Sano, Takatomo; Sunagozaka, Hajime; Uchino, Koji; Minami, Yasunori; Saito, Yu; Nagai, Kazumasa; Inokuchi, Ryosuke; Kokubu, Shigehiro; Kudo, Masatoshi

    2014-01-01

    In order to attain better ablation and more effective management of hepatocellular carcinoma (HCC), new approaches and devices in radiofrequency ablation (RFA) therapy were presented and discussed in a workshop at the 50th Annual Meeting of the Liver Cancer Study Group of Japan. A novel bipolar RFA apparatus was introduced in Japan in January 2013. Hundreds of subjects with HCC were treated with multipolar RFA with varied devices and plans. Among these, no-touch ablation was one of the most useful procedures in the treatment of HCC with the apparatus. In RFA therapy, a few assisting devices and techniques were applied for convenience and improvement of the thermal ablation procedure. Contrast-enhanced ultrasonography and three-dimensional fusion imaging technique using volume data of CT or MRI could improve exact targeting and shorten the treatment time for RFA procedures under ultrasonographic guidance. A more complicated method using a workstation was also reported as being helpful in planning the ablated shape and volume in multineedle RFA. The effective use of sedatives and antianalgesics as well as a novel microwave apparatus with a cooled-tip electrode was also discussed. PMID:25427736

  10. Investigation of radiofrequency plasma sources for space travel

    NASA Astrophysics Data System (ADS)

    Charles, C.; Boswell, R. W.; Takahashi, K.

    2012-12-01

    Optimization of radiofrequency (RF) plasma sources for the development of space thrusters differs from other applications such as plasma processing of materials since power efficiency, propellant usage, particle acceleration or heating become driving parameters. The development of two RF (13.56 MHz) plasma sources, the high-pressure (˜1 Torr) capacitively coupled ‘pocket rocket’ plasma micro-thruster and the low-pressure (˜1 mTorr) inductively coupled helicon double layer thruster (HDLT), is discussed within the context of mature and emerging electric propulsion devices. The density gradient in low-pressure expanding RF plasmas creates an electric field that accelerates positive ions out of the plasma. Generally, the total potential drop is similar to that of a wall sheath allowing the plasma electrons to neutralize the ion beam. A high-pressure expansion with no applied magnetic field can result in large dissociation rates and/or a collimated beam of ions of small area and a flowing heated neutral beam (‘pocket rocket’). A low-pressure expansion dominated by a magnetic field can result in the formation of electric double layers which produce a very directed neutralized beam of ions of large area (HDLT).

  11. Radio-frequency capacitance spectroscopy of metallic nanoparticles.

    PubMed

    Frake, James C; Kano, Shinya; Ciccarelli, Chiara; Griffiths, Jonathan; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka; Smith, Charles G; Buitelaar, Mark R

    2015-01-01

    Recent years have seen great progress in our understanding of the electronic properties of nanomaterials in which at least one dimension measures less than 100 nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge as even state-of-the-art nanofabrication techniques such as electron-beam lithography have a resolution of a few nm at best. Here we present a fabrication and measurement technique that allows high sensitivity and high bandwidth readout of discrete quantum states of metallic nanoparticles which does not require nm resolution or precision. This is achieved by coupling the nanoparticles to resonant electrical circuits and measurement of the phase of a reflected radio-frequency signal. This requires only a single tunnel contact to the nanoparticles thus simplifying device fabrication and improving yield and reliability. The technique is demonstrated by measurements on 2.7 nm thiol coated gold nanoparticles which are shown to be in excellent quantitative agreement with theory. PMID:26042729

  12. Pushing the limits of radiofrequency (RF) neuronal telemetry.

    PubMed

    Yousefi, Tara; Diaz, Rodolfo E

    2015-01-01

    In a previous report it was shown that the channel capacity of an in vivo communication link using microscopic antennas at radiofrequency is severely limited by the requirement not to damage the tissue surrounding the antennas. For dipole-like antennas the strong electric field dissipates too much power into body tissues. Loop-type antennas have a strong magnetic near field and so dissipate much less power into the surrounding tissues but they require such a large current that the antenna temperature is raised to the thermal damage threshold of the tissue. The only solution was increasing the antenna size into hundreds of microns, which makes reporting on an individual neuron impossible. However, recently demonstrated true magnetic antennas offer an alternative not covered in the previous report. The near field of these antennas is dominated by the magnetic field yet they don't require large currents. Thus they combine the best characteristics of dipoles and loops. By calculating the coupling between identical magnetic antennas inside a model of the body medium we show an increase in the power transfer of up to 8 orders of magnitude higher than could be realized with the loops and dipoles, making the microscopic RF in-vivo transmitting antenna possible. PMID:26035824

  13. Radio-frequency capacitance spectroscopy of metallic nanoparticles

    PubMed Central

    Frake, James C.; Kano, Shinya; Ciccarelli, Chiara; Griffiths, Jonathan; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka; Smith, Charles G.; Buitelaar, Mark R.

    2015-01-01

    Recent years have seen great progress in our understanding of the electronic properties of nanomaterials in which at least one dimension measures less than 100 nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge as even state-of-the-art nanofabrication techniques such as electron-beam lithography have a resolution of a few nm at best. Here we present a fabrication and measurement technique that allows high sensitivity and high bandwidth readout of discrete quantum states of metallic nanoparticles which does not require nm resolution or precision. This is achieved by coupling the nanoparticles to resonant electrical circuits and measurement of the phase of a reflected radio-frequency signal. This requires only a single tunnel contact to the nanoparticles thus simplifying device fabrication and improving yield and reliability. The technique is demonstrated by measurements on 2.7 nm thiol coated gold nanoparticles which are shown to be in excellent quantitative agreement with theory. PMID:26042729

  14. Delayed Development of Pneumothorax After Pulmonary Radiofrequency Ablation

    SciTech Connect

    Clasen, Stephan; Kettenbach, Joachim; Kosan, Bora; Aebert, Hermann; Schernthaner, Melanie; Kroeber, Stefan-Martin; Boemches, Andrea; Claussen, Claus D.; Pereira, Philippe L.

    2009-05-15

    Acute pneumothorax is a frequent complication after percutaneous pulmonary radiofrequency (RF) ablation. In this study we present three cases showing delayed development of pneumothorax after pulmonary RF ablation in 34 patients. Our purpose is to draw attention to this delayed complication and to propose a possible approach to avoid this major complication. These three cases occurred subsequent to 44 CT-guided pulmonary RF ablation procedures (6.8%) using either internally cooled or multitined expandable RF electrodes. In two patients, the pneumothorax, being initially absent at the end of the intervention, developed without symptoms. One of these patients required chest drain placement 32 h after RF ablation, and in the second patient therapy remained conservative. In the third patient, a slight pneumothorax at the end of the intervention gradually increased and led into tension pneumothorax 5 days after ablation procedure. Underlying bronchopleural fistula along the coagulated former electrode track was diagnosed in two patients. In conclusion, delayed development of pneumothorax after pulmonary RF ablation can occur and is probably due to underlying bronchopleural fistula, potentially leading to tension pneumothorax. Patients and interventionalists should be prepared for delayed onset of this complication, and extensive track ablation following pulmonary RF ablation should be avoided.

  15. Measured radiofrequency exposure during various mobile-phone use scenarios.

    PubMed

    Kelsh, Michael A; Shum, Mona; Sheppard, Asher R; McNeely, Mark; Kuster, Niels; Lau, Edmund; Weidling, Ryan; Fordyce, Tiffani; Kühn, Sven; Sulser, Christof

    2011-01-01

    Epidemiologic studies of mobile phone users have relied on self reporting or billing records to assess exposure. Herein, we report quantitative measurements of mobile-phone power output as a function of phone technology, environmental terrain, and handset design. Radiofrequency (RF) output data were collected using software-modified phones that recorded power control settings, coupled with a mobile system that recorded and analyzed RF fields measured in a phantom head placed in a vehicle. Data collected from three distinct routes (urban, suburban, and rural) were summarized as averages of peak levels and overall averages of RF power output, and were analyzed using analysis of variance methods. Technology was the strongest predictor of RF power output. The older analog technology produced the highest RF levels, whereas CDMA had the lowest, with GSM and TDMA showing similar intermediate levels. We observed generally higher RF power output in rural areas. There was good correlation between average power control settings in the software-modified phones and power measurements in the phantoms. Our findings suggest that phone technology, and to a lesser extent, degree of urbanization, are the two stronger influences on RF power output. Software-modified phones should be useful for improving epidemiologic exposure assessment. PMID:20551994

  16. Wavelet Domain Radiofrequency Pulse Design Applied to Magnetic Resonance Imaging.

    PubMed

    Huettner, Andrew M; Mickevicius, Nikolai J; Ersoz, Ali; Koch, Kevin M; Muftuler, L Tugan; Nencka, Andrew S

    2015-01-01

    A new method for designing radiofrequency (RF) pulses with numerical optimization in the wavelet domain is presented. Numerical optimization may yield solutions that might otherwise have not been discovered with analytic techniques alone. Further, processing in the wavelet domain reduces the number of unknowns through compression properties inherent in wavelet transforms, providing a more tractable optimization problem. This algorithm is demonstrated with simultaneous multi-slice (SMS) spin echo refocusing pulses because reduced peak RF power is necessary for SMS diffusion imaging with high acceleration factors. An iterative, nonlinear, constrained numerical minimization algorithm was developed to generate an optimized RF pulse waveform. Wavelet domain coefficients were modulated while iteratively running a Bloch equation simulator to generate the intermediate slice profile of the net magnetization. The algorithm minimizes the L2-norm of the slice profile with additional terms to penalize rejection band ripple and maximize the net transverse magnetization across each slice. Simulations and human brain imaging were used to demonstrate a new RF pulse design that yields an optimized slice profile and reduced peak energy deposition when applied to a multiband single-shot echo planar diffusion acquisition. This method may be used to optimize factors such as magnitude and phase spectral profiles and peak RF pulse power for multiband simultaneous multi-slice (SMS) acquisitions. Wavelet-based RF pulse optimization provides a useful design method to achieve a pulse waveform with beneficial amplitude reduction while preserving appropriate magnetization response for magnetic resonance imaging. PMID:26517262

  17. Pushing the limits of radiofrequency (RF) neuronal telemetry

    PubMed Central

    Yousefi, Tara; Diaz, Rodolfo E.

    2015-01-01

    In a previous report it was shown that the channel capacity of an in vivo communication link using microscopic antennas at radiofrequency is severely limited by the requirement not to damage the tissue surrounding the antennas. For dipole-like antennas the strong electric field dissipates too much power into body tissues. Loop-type antennas have a strong magnetic near field and so dissipate much less power into the surrounding tissues but they require such a large current that the antenna temperature is raised to the thermal damage threshold of the tissue. The only solution was increasing the antenna size into hundreds of microns, which makes reporting on an individual neuron impossible. However, recently demonstrated true magnetic antennas offer an alternative not covered in the previous report. The near field of these antennas is dominated by the magnetic field yet they don’t require large currents. Thus they combine the best characteristics of dipoles and loops. By calculating the coupling between identical magnetic antennas inside a model of the body medium we show an increase in the power transfer of up to 8 orders of magnitude higher than could be realized with the loops and dipoles, making the microscopic RF in-vivo transmitting antenna possible. PMID:26035824

  18. Operating a radio-frequency plasma source on water vapor.

    PubMed

    Nguyen, Sonca V T; Foster, John E; Gallimore, Alec D

    2009-08-01

    A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires n(i) approximately = n(e), where n(i) is the positive ion density. But in the electronegative water plasma, quasineutrality requires n(i+) = n(i-) + n(e). The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production. PMID:19725651

  19. Surgical and Pathological Changes after Radiofrequency Ablation of Thyroid Nodules

    PubMed Central

    Dobrinja, Chiara; Bernardi, Stella; Fabris, Bruno; Eramo, Rita; Makovac, Petra; Bazzocchi, Gabriele; Piscopello, Lanfranco; Barro, Enrica; de Manzini, Nicolò; Bonazza, Deborah; Pinamonti, Maurizio; Zanconati, Fabrizio; Stacul, Fulvio

    2015-01-01

    Background. Radiofrequency ablation (RFA) has been recently advocated as an effective technique for the treatment of symptomatic benign thyroid nodules. It is not known to what extent it may affect any subsequent thyroid surgery and/or histological diagnosis. Materials and Methods. RFA was performed on 64 symptomatic Thy2 nodules (benign nodules) and 6 symptomatic Thy3 nodules (follicular lesions/follicular neoplasms). Two Thy3 nodules regrew after the procedure, and these patients accepted to undergo a total thyroidectomy. Here we present how RFA has affected the operation and the final pathological features of the surgically removed nodules. Results and Conclusions. RFA is effective for the treatment of Thy2 nodules, but it should not be recommended as first-line therapy for the treatment of Thy3 nodules (irrespective of their mutational status), as it delays surgery in case of malignancy. Moreover, it is unknown whether RFA might promote residual tumor progression or neoplastic progression of Thy3 lesions. Nevertheless, here we show for the first time that one session of RFA does not affect subsequent thyroid surgery and/or histological diagnosis. PMID:26265914

  20. Radio-frequency energy harvesting for wearable sensors

    PubMed Central

    Chávez-Santiago, Raul; Barroca, Norberto; Velez, Fernando José; Balasingham, Ilangko

    2015-01-01

    The use of wearable biomedical sensors for the continuous monitoring of physiological signals will facilitate the involvement of the patients in the prevention and management of chronic diseases. The fabrication of small biomedical sensors transmitting physiological data wirelessly is possible as a result of the tremendous advances in ultra-low power electronics and radio communications. However, the widespread adoption of these devices depends very much on their ability to operate for long periods of time without the need to frequently change, recharge or even use batteries. In this context, energy harvesting (EH) is the disruptive technology that can pave the road towards the massive utilisation of wireless wearable sensors for patient self-monitoring and daily healthcare. Radio-frequency (RF) transmissions from commercial telecommunication networks represent reliable ambient energy that can be harvested as they are ubiquitous in urban and suburban areas. The state-of-the-art in RF EH for wearable biomedical sensors specifically targeting the global system of mobile 900/1800 cellular and 700 MHz digital terrestrial television networks as ambient RF energy sources are showcased. Furthermore, guidelines for the choice of the number of stages for the RF energy harvester are presented, depending on the requirements from the embedded system to power supply, which is useful for other researchers that work in the same area. The present authors' recent advances towards the development of an efficient RF energy harvester and storing system are presented and thoroughly discussed too. PMID:26609400

  1. Radio-frequency quadrupole vane-tip geometries

    SciTech Connect

    Crandall, K.R.; Mills, R.S.; Wangler, T.P.

    1983-01-01

    Radio-frequency quadrupole (RFQ) linacs are becoming widely accepted in the accelerator community. They have the remarkable capability of simultaneously bunching low-energy ion beams and accelerating them to energies at which conventional accelerators can be used, accomplishing this with high-transmission efficiencies and low-emittance growths. The electric fields, used for radial focusing, bunching, and accelerating, are determined by the geometry of the vane tips. The choice of the best vane-tip geometry depends on considerations such as the peak surface electric field, per cent of higher multipole components, and ease of machining. We review the vane-tip geometry based on the ideal two-term potential function and briefly describe a method for calculating the electric field components in an RFQ cell with arbitrary vane-tip geometry. We describe five basic geometries and use the prototype RFQ design for the Fusion Materials Irradiation Test (FMIT) accelerator as an example to compare the characteristics of the various geometries.

  2. Radio-frequency quadrupole vane-tip geometries

    SciTech Connect

    Crandall, K.R.; Mills, R.S.; Wangler, T.P.

    1983-08-01

    Radio-frequency quadrupole (RFQ) linacs are becoming widely accepted in the accelerator community. They have the remarkable capability of simultaneously bunching low-energy ion beams and accelerating them to energies at which conventional accelerators can be used, accomplishing this with high transmission efficiencies and low-emittance growths. The electric fields, used for radial focusing, bunching, and accelerating, are determined by the geometry of the vane tips. The choice of the best vane-tip geometry depends on considerations such as the peak surface electric field, per cent of higher multipole components, and ease of machining. The authors review the vane-tip geometry based on the ''ideal'' two-term potential function and briefly describe a method for calculating the electric field components in an RFQ cell with arbitrary vane-tip geometry. They describe five basic geometries and use the prototype RFQ design for the Fusion Materials Irradiation Test (FMIT) accelerator as an example to compare the characteristics of the various geometries.

  3. Experimental study of a high intensity radio-frequency cooler

    NASA Astrophysics Data System (ADS)

    Boussaid, Ramzi; Ban, G.; Cam, J. F.

    2015-07-01

    Within the framework of the DESIR/SPIRAL-2 project, a radio-frequency quadrupole cooler named SHIRaC has been studied. SHIRaC is a key device of SPIRAL-2, designed to enhance the beam quality required by DESIR. The preliminary study and development of this device has been carried out at Laboratoire de Physique Corpusculaire de CAEN (LPC Caen), France. The goal of this paper is to present the experimental studies conducted on a SHIRaC prototype. The main peculiarity of this cooler is its efficient handling and cooling of ion beams with currents going up as high as 1 μ A which has never before been achieved in any of the previous coolers. Much effort has been made lately into these studies for development of appropriate optics, vacuum and rf systems which allow cooling of beams of large emittance (˜80 π mm mrad ) and high current. The dependencies of SHIRaC's transmission and the cooled beam parameters in terms of geometrical transverse emittance and the longitudinal energy spread have also been discussed. Investigation of beam purity at optimum cooling condition has also been done. Results from the experiments indicate that an emittance reduction of less than 2.5 π mm mrad and a longitudinal energy spread reduction of less than 4 eV are obtained with more than 70% of ion transmission. The emittance is at expected values whereas the energy spread is not.

  4. An anatomically realistic temperature phantom for radiofrequency heating measurements

    PubMed Central

    Graedel, Nadine N.; Polimeni, Jonathan R.; Guerin, Bastien; Gagoski, Borjan; Wald, Lawrence L.

    2014-01-01

    Purpose An anthropomorphic phantom with realistic electrical properties allows for a more accurate reproduction of tissue current patterns during excitation. A temperature map can then probe the worst-case heating expected in the un-perfused case. We describe an anatomically realistic human head phantom that allows rapid 3D temperature mapping at 7 T. Methods The phantom was based on hand-labeled anatomical imaging data and consists of four compartments matching the corresponding human tissues in geometry and electrical properties. The increases in temperature resulting from radiofrequency excitation were measured with MR thermometry using a temperature sensitive contrast agent (TmDOTMA−) validated by direct fiber optic temperature measurements. Results Acquisition of 3D temperature maps of the full phantom with a temperature accuracy better than 0.1°C was achieved with an isotropic resolution of 5 mm and acquisition times of 2–4 minutes. Conclusion Our results demonstrate the feasibility of constructing anatomically realistic phantoms with complex geometries incorporating the ability to measure accurate temperature maps in the phantom. The anthropomorphic temperature phantom is expected to provide a useful tool for the evaluation of the heating effects of both conventional and parallel transmit pulses and help validate electromagnetic and temperature simulations. PMID:24549755

  5. Incidence and Cause of Hypertension During Adrenal Radiofrequency Ablation

    SciTech Connect

    Yamakado, Koichiro Takaki, Haruyuki; Yamada, Tomomi; Yamanaka, Takashi; Uraki, Junji; Kashima, Masataka; Nakatsuka, Atsuhiro; Takeda, Kan

    2012-12-15

    Purpose: To evaluate the incidence and cause of hypertension prospectively during adrenal radiofrequency ablation (RFA). Methods: For this study, approved by our institutional review board, written informed consent was obtained from all patients. Patients who received RFA for adrenal tumors (adrenal ablation) and other abdominal tumors (nonadrenal ablation) were included in this prospective study. Blood pressure was monitored during RFA. Serum adrenal hormone levels including epinephrine, norepinephrine, dopamine, and cortisol levels were measured before and during RFA. The respective incidences of procedural hypertension (systolic blood pressure >200 mmHg) of the two patient groups were compared. Factors correlating with procedural systolic blood pressure were evaluated by regression analysis.ResultsNine patients underwent adrenal RFA and another 9 patients liver (n = 5) and renal (n = 4) RFA. Asymptomatic procedural hypertension that returned to the baseline by injecting calcium blocker was found in 7 (38.9%) of 18 patients. The incidence of procedural hypertension was significantly higher in the adrenal ablation group (66.7%, 6/9) than in the nonadrenal ablation group (11.1%, 1/9, P < 0.0498). Procedural systolic blood pressure was significantly correlated with serum epinephrine (R{sup 2} = 0.68, P < 0.0001) and norepinephrine (R{sup 2} = 0.72, P < 0.0001) levels during RFA. The other adrenal hormones did not show correlation with procedural systolic blood pressure. Conclusion: Hypertension occurs frequently during adrenal RFA because of the release of catecholamine.

  6. Radiofrequency Ablation of Lung Malignancies: Where Do We Stand?

    SciTech Connect

    Lencioni, Riccardo Crocetti, Laura; Cioni, Roberto; Mussi, Alfredo; Fontanini, Gabriella; Ambrogi, Marcello; Franchini, Chiara; Cioni, Dania; Fanucchi, Olivia; Gemignani, Raffaello; Baldassarri, Rubia; Angeletti, Carlo Alberto; Bartolozzi, Carlo

    2004-11-15

    Percutaneous radiofrequency (RF) ablation is a minimally invasive technique used to treat solid tumors. Because of its ability to produce large volumes of coagulation necrosis in a controlled fashion, this technique has gained acceptance as a viable therapeutic option for unresectable liver malignancies. Recently, investigation has been focused on the clinical application of RF ablation in the treatment of lung malignancies. In theory, lung tumors are well suited to RF ablation because the surrounding air in adjacent normal parenchyma provides an insulating effect, thus facilitating energy concentration within the tumor tissue. Experimental studies in rabbits have confirmed that lung RF ablation can be safely and effectively performed via a percutaneous, transthoracic approach, and have prompted the start of clinical investigation. Pilot clinical studies have shown that RF ablation enables successful treatment of relatively small lung malignancies with a high rate of complete response and acceptable morbidity, and have suggested that the technique could represent a viable alternate or complementary treatment method for patients with non-small cell lung cancer or lung metastases of favorable histotypes who are not candidates for surgical resection. This article gives an overview of lung RF ablation, discussing experimental animal findings, rationale for clinical application, technique and methodology, clinical results, and complications.

  7. Percutaneous radiofrequency ablation of spinal osteoid osteoma under CT guidance

    PubMed Central

    Morassi, L G; Kokkinis, K; Karargyris, O; Vlachou, I; Kalokairinou, K; Pneumaticos, S G

    2014-01-01

    Objective: Osteoid osteoma (OO) accounts for approximately 10–12% of all benign bone tumours and 3% of all bone tumours. Spinal involvement appears in 10–25% of all cases. The purpose of this study was to evaluate the safety and efficacy of CT-guided radiofrequency (RF) ablation in the treatment of spinal OOs and report our experience. Methods: 13 patients suffering from spinal OO and treated at the authors' institution using CT-guided RF ablation were retrospectively evaluated. The RF probe was introduced through a 11-G Jamshidi® needle, and the lesion was heated at 90 °C for 6 min. Results: All procedures were considered technically successful as the correct positioning of the probe was proven by CT. 11 of the 13 patients reported pain relief after RF ablation. In two cases, RF ablation was repeated 1 month after the first procedure. Pain relief was achieved in both cases after the second procedure. No recurrence was reported throughout the follow-up. No complications like skin burn, soft-tissue haematoma, infection, vessel damage or neurological deficit were reported. Conclusion: This study demonstrates that CT-guided percutaneous RF ablation is a safe and effective method for the treatment of spinal OOs. Advances in knowledge: The data of this study support the efficacy and safety of the recently applied CT-guided percutaneous RF ablation technique for the treatment of spinal OOs. PMID:24712322

  8. Quality Improvement Guidelines for Radiofrequency Ablation of Liver Tumours

    SciTech Connect

    Crocetti, Laura; Baere, Thierry de; Lencioni, Riccardo

    2010-02-15

    The development of image-guided percutaneous techniques for local tumour ablation has been one of the major advances in the treatment of liver malignancies. Among these methods, radiofrequency ablation (RFA) is currently established as the primary ablative modality at most institutions. RFA is accepted as the best therapeutic choice for patients with early-stage hepatocellular carcinoma (HCC) when liver transplantation or surgical resection are not suitable options [1, 2]. In addition, RFA is considered a viable alternate to surgery (1) for inoperable patients with limited hepatic metastatic disease, especially from colorectal cancer, and (2) for patients deemed ineligible for surgical resection because of extent and location of the disease or concurrent medical conditions [3]. These guidelines were written to be used in quality-improvement programs to assess RFA of HCC and liver metastases. The most important processes of care are (1) patient selection, (2) performing the procedure, and (3) monitoring the patient. The outcome measures or indicators for these processes are indications, success rates, and complication rates.

  9. Treatment of Acne Scars of Skin Types II to V by Sublative Fractional Bipolar Radiofrequency and Bipolar Radiofrequency Combined with Diode Laser

    PubMed Central

    Garretson, Cara Beth

    2011-01-01

    Objective: This study evaluated the safety and efficacy of sublative fractional bipolar radiofrequency and bipolar radio frequency combined with diode laser for the treatment of both superficial and deep acne scars in patients with skin types II to V. Design: Prospective, single-center study. Subjects received up to five treatments with sublative fractional bipolar radiofrequency and bipolar radiofrequency combined with diode laser. Treatments were directed to at least two facial (forehead, perioral, cheeks) and/or neck areas with acne scars at four-week intervals. Treatment parameters on each subject were based on skin type and on skin responses to test spots on the target area just before treatment. Setting: Physician office. Participants: Subjects (n=20, aged 40.7±10.5 years [mean ± SD], skin types II–V) with acne scars and without acne lesions enrolled in this prospective study. Measurements: Results were evaluated just before each treatment and at four and 12 weeks after the final treatment using the Goodman Scar Scale, a quantitative method of evaluating scars that attempts to reduce grading subjectivity, as well as by patient satisfaction. Results: Acne scars improved significantly one month after three treatments and improvement persisted for at least 12 weeks after the fifth treatment. Improvement was not affected by skin type. Adverse effects were limited to transient erythema and edema. Conclusion: The combination of diode laser and bipolar radiofrequency energy device in addition to fractionated sublative radiofrequency is a safe and statistically significantly effective combined modality for the treatment of both superficial and deep acne scars in patients with skin types II to V with minimal downtime and no significant side effects. PMID:22010052

  10. Assessment of levels of occupational exposure to workers in radiofrequency fields of two television stations in Accra, Ghana.

    PubMed

    Osei, S; Amoako, J K; Fletcher, J J

    2016-03-01

    A survey of the radiofrequency (RF) radiation was undertaken within the premises of two television (TV) stations, TVA and TVB, in Accra, Ghana. The primary objective of this study was to determine the level of RF exposure to workers in the TV stations. A spectrum analyser, a bi-conical antenna (30-300 MHz) and a log-periodic antenna (200 MHz-2.0 GHz) were used. Results obtained indicated that the wideband electric field strength levels recorded in this work vary between 0.006 and 58.5 V m(-1) at TVA and between 0.007 and 28.5 V m(-1) at TVB. Compared with the results from TVB, TVA recorded relatively higher values in the 30-400 MHz range, whereas TVB produced relatively higher values in the 400 MHz-1.7 GHz range. Generally, results obtained were found to be below the occupational reference levels of the International Commission on Non-Ionizing Radiation Protection, but at some locations, the field intensity was 4.3 times higher than the reference levels for the general public. PMID:25979743

  11. Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Shen, Hao; Fan, Li; Wu, Rui; Niu, Ben; Varghese, Leo T.; Xuan, Yi; Leaird, Daniel E.; Wang, Xi; Gan, Fuwan; Weiner, Andrew M.; Qi, Minghao

    2015-01-01

    Photonic methods of radio-frequency waveform generation and processing can provide performance advantages and flexibility over electronic methods due to the ultrawide bandwidth offered by the optical carriers. However, bulk optics implementations suffer from the lack of integration and slow reconfiguration speed. Here we propose an architecture of integrated photonic radio-frequency generation and processing and implement it on a silicon chip fabricated in a semiconductor manufacturing foundry. Our device can generate programmable radio-frequency bursts or continuous waveforms with only the light source, electrical drives/controls and detectors being off-chip. It modulates an individual pulse in a radio-frequency burst within 4 ns, achieving a reconfiguration speed three orders of magnitude faster than thermal tuning. The on-chip optical delay elements offer an integrated approach to accurately manipulating individual radio-frequency waveform features without constraints set by the speed and timing jitter of electronics, and should find applications ranging from high-speed wireless to defence electronics.

  12. Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip

    PubMed Central

    Wang, Jian; Shen, Hao; Fan, Li; Wu, Rui; Niu, Ben; Varghese, Leo T.; Xuan, Yi; Leaird, Daniel E.; Wang, Xi; Gan, Fuwan; Weiner, Andrew M.; Qi, Minghao

    2015-01-01

    Photonic methods of radio-frequency waveform generation and processing can provide performance advantages and flexibility over electronic methods due to the ultrawide bandwidth offered by the optical carriers. However, bulk optics implementations suffer from the lack of integration and slow reconfiguration speed. Here we propose an architecture of integrated photonic radio-frequency generation and processing and implement it on a silicon chip fabricated in a semiconductor manufacturing foundry. Our device can generate programmable radio-frequency bursts or continuous waveforms with only the light source, electrical drives/controls and detectors being off-chip. It modulates an individual pulse in a radio-frequency burst within 4 ns, achieving a reconfiguration speed three orders of magnitude faster than thermal tuning. The on-chip optical delay elements offer an integrated approach to accurately manipulating individual radio-frequency waveform features without constraints set by the speed and timing jitter of electronics, and should find applications ranging from high-speed wireless to defence electronics. PMID:25581847

  13. Target radiofrequency combined with collagenase chemonucleolysis in the treatment of lumbar intervertebral disc herniation

    PubMed Central

    Zhang, Daying; Zhang, Yong; Wang, Zhijian; Zhang, Xuexue; Sheng, Mulan

    2015-01-01

    Both target radiofrequency thermocoagulation and collagenase chemonucleolysis are effective micro-invasive therapy means for lumbar intervertebral disc herniation. In order to analyze the clinical effects of target radiofrequency thermocoagulation combined with collagenase chemonucleolysis on lumbar intervertebral disc herniation, the contents of hydroxyproline and glycosaminoglycan were measured and the histological changes of nucleus pulposus was detected in the vitro experiments. Radiofrequency thermocoagulation reduced the hydrolyzation of herniated nucleus pulposus caused by collagenase, as well as the content of hydroxyproline and glycosaminoglycan. Furthermore, 236 patients with lumbar intervertebral disc herniation were treated by target radiofrequency thermocoagulation combined with collagenase chemonucleolysis. The efficiency was evaluated according to Macnab criteria, and the index of lumbar disc herniation (IDH) was compared pre-operation with 3 months post-operation. The post-operative good rate was 66.5% (157/236) at 2 weeks post-operation, and 88.1% (208/236) at 3 months post-operation. In the post-operative follow-up exam, 86.8% of the re-examined cases demonstrated smaller or ablated protrusion, with reduced IDH values from pre-operation, which was statistically significant. No serious complications were detected intra-operatively and post-operatively. In conclusion, target radiofrequency combined with collagenase chemonucleolysis was an effective and safe method for treatment of lumbar intervertebral disc herniation. PMID:25785026

  14. Radiofrequency preserves histoarchitecture and enhances collagen synthesis in experimental tendon injury.

    PubMed

    Akamatsu, Flavia Emi; Saleh, Samir Omar; Hojaij, Flávio; Martinez, Carlos Augusto Real; Andrade, Mauro; Teodoro, Walcy Rosolia; Jacomo, Alfredo Luiz

    2016-05-01

    We investigated the action of radiofrequency (RF) on the healing process after inducing experimental lesions of the Achilles tendon in rats. Wistar rats were surgically subjected to bilateral partial transverse sectioning of the Achilles tendon. The right tendon was treated with radiofrequency (RFT), whereas the left tendon served as a control (CT). On the third postoperative day, the rats were divided into three experimental groups consisting of ten rats each, which were treated with monopolar radiofrequency (Tonederm™) until they were sacrificed on the 7th, 14th or 28th days. The histological specimens were studied for inflammatory cell content, collagen types I and III, immunostaining and morphometry. Total collagen were biochemically analyzed and to evalute fibroblast and myofibroblast proliferation by vimentin and α-actin smooth muscle immunohistochemistry methods. Statistical analysis was performed using the Student's t-test, the sign test and the Kruskal-Wallis test to compare tendons treated with radiofrequency with the non-treated tendons (α=5%; α=10%). Larger amounts of collagen I with hydroxyproline content and myofibroblast cells were clearly evident within 7 days (p<0.05). No difference was observed in the inflammatory cell content between the groups. We found better collagen arrangement with RF administration across the entire time studied. Radiofrequency administration preserves histoarchitecture and enhances collagen synthesis during the initial phases of cicatrization, suggesting that the treatment can provide improved stiffness during the most vulnerable phases of tendon healing. Clinical studies may include RF among the therapeutic tools in tendinous lesion management. PMID:26337455

  15. Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip.

    PubMed

    Wang, Jian; Shen, Hao; Fan, Li; Wu, Rui; Niu, Ben; Varghese, Leo T; Xuan, Yi; Leaird, Daniel E; Wang, Xi; Gan, Fuwan; Weiner, Andrew M; Qi, Minghao

    2015-01-01

    Photonic methods of radio-frequency waveform generation and processing can provide performance advantages and flexibility over electronic methods due to the ultrawide bandwidth offered by the optical carriers. However, bulk optics implementations suffer from the lack of integration and slow reconfiguration speed. Here we propose an architecture of integrated photonic radio-frequency generation and processing and implement it on a silicon chip fabricated in a semiconductor manufacturing foundry. Our device can generate programmable radio-frequency bursts or continuous waveforms with only the light source, electrical drives/controls and detectors being off-chip. It modulates an individual pulse in a radio-frequency burst within 4 ns, achieving a reconfiguration speed three orders of magnitude faster than thermal tuning. The on-chip optical delay elements offer an integrated approach to accurately manipulating individual radio-frequency waveform features without constraints set by the speed and timing jitter of electronics, and should find applications ranging from high-speed wireless to defence electronics. PMID:25581847

  16. Evaluation of the current radiofrequency ablation systems using axiomatic design theory.

    PubMed

    Zhang, Bing; Moser, Michael A J; Luo, Yigang; Zhang, Edwin M; Zhang, Wenjun

    2014-04-01

    This article evaluates current radiofrequency ablation systems using axiomatic design theory. Due to its minimally invasive procedure, short-time hospital stay, low cost, and tumour metastasis treatment, the radiofrequency ablation technique has been playing an important role in tumour treatment in recent decades. Although the radiofrequency ablation technique has many advantages, some issues still need to be addressed. Among these issues, the two most important are as follows: (1) the size of tumours to be removed (has to be larger than 3 cm in diameter) and (2) cleanness of the removal. Many device solutions have been proposed to address the two issues. However, there is a lack of knowledge regarding the systematic evaluation of these solutions. This article evaluates these systems in terms of their solution principles (or simply called conceptual design in general product design theory) using a design theory called axiomatic design theory. In addition, with the axiomatic design theory, a better conceptual design in terms of its feasibility to cope with incomplete target tissue necrosis from the large size of tumours has been found. The detailed analysis and simulation of the new conceptual design are conducted using finite element approach. The results in this article are proved by the information of animal experiments and clinical practices obtained from the literature. This study thus contributes to the current knowledge to further developments in radiofrequency ablation systems and procedure guidelines for physicians to perform the radiofrequency ablation operation more effectively. PMID:24705341

  17. Radiofrequency catheter ablation of accessory atrioventricular pathways in children and young adults.

    PubMed Central

    Sreeram, N; Smeets, J L; Pulles-Heintzberger, C F; Wellens, H J

    1993-01-01

    OBJECTIVE--To assess the efficacy of radiofrequency ablation for reentrant tachyarrhythmias in children and young adults. SETTING--A tertiary cardiac referral centre. PATIENTS AND INTERVENTIONS--Over a 16 month period 22 patients aged less than 20 years (median age 16.5 years) underwent 26 radiofrequency ablation procedures for atrioventricular reentry tachycardia through an accessory pathway. The results of radiofrequency ablation were compared with those in a group of 16 patients (median age 14 years) who had had surgical ablation for atrioventricular reentry tachycardia over a preceding six year period. RESULTS--Ablation of an accessory atrioventricular pathway was accomplished for 18 (76%) of 25 pathways in 16 (73%) of 22 patients. There were no procedure-related complications. Surgery was eventually curative in 15/16 patients (94%). However, three patients required a second open heart surgical procedure because tachyarrhythmia recurred. There were no surgical deaths. Failures for radiofrequency ablation were related to accessory pathway location, and were greater for right free wall and posteroseptal pathways (success rate of 50% and 57% respectively). Recurrence after surgery was also associated with pathways in these locations. CONCLUSIONS--Transcatheter radiofrequency current ablation was safe and achieved a cure with less patient morbidity and improved cost efficiency. It is an attractive alternative to long-term drug therapy or surgery in older children and adolescents. A higher success rate may be expected with increased experience. PMID:8038027

  18. Pulsed radiofrequency on radial nerve under ultrasound guidance for treatment of intractable lateral epicondylitis.

    PubMed

    Oh, Dae Seok; Kang, Tae Hyung; Kim, Hyae Jin

    2016-06-01

    Lateral epicondylitis is a painful and functionally limiting disorder. Although lateral elbow pain is generally self-limiting, in a minority of people symptoms persist for a long time. When various conservative treatments fail, surgical approach is recommended. Surgical denervation of several nerves that innervate the lateral humeral epicondyle could be considered in patients with refractory pain because it denervates the region of pain. Pulsed radiofrequency is a minimally invasive procedure that improves chronic pain when applied to various neural tissues without causing any significant destruction and painful complication. This procedure is safe, minimally invasive, and has less risk of complications relatively compared to the surgical approach. The radial nerve can be identified as a target for pulsed radiofrequency lesioning in lateral epicondylitis. This innovative method of pulsed radiofrequency applied to the radial nerve has not been reported before. We reported on two patients with intractable lateral epicondylitis suffering from elbow pain who did not respond to nonoperative treatments, but in whom the ultrasound-guided pulsed radiofrequency neuromodulation of the radial nerve induced symptom improvement. After a successful diagnostic nerve block, radiofrequency probe adjustment around the radial nerve was performed on the lateral aspect of the distal upper arm under ultrasound guidance and multiple pulsed treatments were applied. A significant reduction in pain was reported over the follow-up period of 12 weeks. PMID:26896944

  19. Optoacoustic monitoring of real-time lesion formation during radiofrequency catheter ablation

    NASA Astrophysics Data System (ADS)

    Pang, Genny A.; Bay, Erwin; Deán-Ben, Xosé L.; Razansky, Daniel

    2015-03-01

    Current radiofrequency cardiac ablation procedures lack real-time lesion monitoring guidance, limiting the reliability and efficacy of the treatment. The objective of this work is to demonstrate that optoacoustic imaging can be applied to develop a diagnostic technique applicable to radiofrequency ablation for cardiac arrhythmia treatment with the capabilities of real-time monitoring of ablated lesion size and geometry. We demonstrate an optoacoustic imaging method using a 256-detector optoacoustic imaging probe and pulsed-laser illumination in the infrared wavelength range that is applied during radiofrequency ablation in excised porcine myocardial tissue samples. This technique results in images with high contrast between the lesion volume and unablated tissue, and is also capable of capturing time-resolved image sequences that provide information on the lesion development process. The size and geometry of the imaged lesion were shown to be in excellent agreement with the histological examinations. This study demonstrates the first deep-lesion real-time monitoring for radiofrequency ablation generated lesions, and the technique presented here has the potential for providing critical feedback that can significantly impact the outcome of clinical radiofrequency ablation procedures.

  20. Radiofrequency Energy Deposition and Radiofrequency Power Requirements in Parallel Transmission with Increasing Distance from the Coil to the Sample

    PubMed Central

    Deniz, Cem M.; Vaidya, Manushka V.; Sodickson, Daniel K.; Lattanzi, Riccardo

    2015-01-01

    Purpose We investigated global specific absorption rate (SAR) and radiofrequency (RF) power requirements in parallel transmission as the distance between the transmit coils and the sample was increased. Methods We calculated ultimate intrinsic SAR (UISAR), which depends on object geometry and electrical properties but not on coil design, and we used it as the reference to compare the performance of various transmit arrays. We investigated the case of fixing coil size and increasing the number of coils while moving the array away from the sample, as well as the case of fixing coil number and scaling coil dimensions. We also investigated RF power requirements as a function of liftoff, and tracked local SAR distributions associated with global SAR optima. Results In all cases, the target excitation profile was achieved and global SAR (as well as associated maximum local SAR) decreased with lift-off, approaching UISAR, which was constant for all lift-offs. We observed a lift-off value that optimizes the balance between global SAR and power losses in coil conductors. We showed that, using parallel transmission, global SAR can decrease at ultra high fields for finite arrays with a sufficient number of transmit elements. Conclusion For parallel transmission, the distance between coils and object can be optimized to reduce SAR and minimize RF power requirements associated with homogeneous excitation. PMID:25752250