PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Radiation, Nonionizing”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Plantar fibromatosis: staging by magnetic resonance imaging.

Plantar fibromatosis is a slow growing nodular thickening that occurs most often within the central band of the plantar aponeurosis. Since the lesion is not encapsulated, clinical margins are often difficult to define. Inadequate excision is the primary cause of recurrence. MRI is a nonionizing radiation technique that demonstrates excellent definition between pathological entities and normal anatomy. This may aid in the preoperative planning.

Fibroma↗
PubMed1995

[Changes in the status of the adaptation of workers at the television relay station on top of Botev Peak].

The state of adaptation of subjects (numbering 17) occupied at Botev Peak TV relay station and thereby exposed to nonionizing radiations--electromagnetic fields (EMF)--was monitored by following changes in analysis of cardiac variance (ACV) indicators. In addition to these, other physiologic indicators studied were systolic and diastolic blood pressure, as well as psychologic indicators, notably, psychosomatic complaints as early manifestations of disturbance in the state of adaptation. Data from the group of subjects studied were compared to those of a control group whose working conditions involved no EMF exposure. This comparison, based on ACV indicators (mean--mean value of successive cardiac intervals, SD--standard deviation of mean value of cardiac intervals (R-R), AMo--amplitude of the mode, SI, ABI, HI--homeostatic index, CP--classification parameter, IC), psychosomatic complaints, systolic and diastolic blood pressure, provided no evidence of reduction of adaptive reserves or deterioration of somatic and mental health state in occupationally exposed workers at Botev Peak TV relay station.

Adaptation, Physiological↗
PubMed1996

[An experimental in-vitro evaluation of membrane antigen expression and of interleukin production by monocytes exposed to magnetic resonance].

The interactions of magnetic fields and radiofrequency with biological systems have been described by several authors. However, no definitive conclusions have been drawn yet as to the safety of the magnetic fields and radiofrequencies used in clinical examinations. The immune system is one of the most complex biological systems, in which a network of intracellular signals regulates the immune response. Interleukins are released by an activation process which involves, at least in part, intra- and/or extracellular calcium mobilization. The latter step can be influenced by the in vitro effect of this type of nonionizing radiations produced by an MR system on peripheral blood mononuclear cells. Our results show that the 2-hour exposure to magnetic fields (0.5 T) and radiofrequency caused an increase in the spontaneous release of IL2, IL4, IL10, TNF alpha and INF gamma, while the amount of the same cytokines induced by PHA stimulation was decreased. No differences were observed in the spontaneous or PHA-induced release of IL6 by exposure to magnetic fields (MRI). Furthermore, the expression of the CD 11b molecule was increased at the same time. These results may be useful for us to understand the interactions between magnetic fields and radiofrequencies and the immune system.

Antigens, Surface↗
PubMed1996

[A quantitative in-vitro analysis of the effects of magnetic fields and radiofrequencies on amino acid metabolism].

The extensive use of magnetic resonance imaging in medical diagnosis needs experimental confirmation of the real biological harmlessness of magnetic fields and radiofrequencies in the imaging process. To date, no unquestionable conclusions have been drawn and experimental results differ in various literature reports. We investigated the effects of radiofrequencies and magnetic fields on the amino acid content of plasma samples from 10 healthy volunteers aged 25 to 30 years; the samples were exposed for 60 minutes to MR fields at 0.5 T with the sequences commonly used in clinical practice. After exposure to magnetic fields, the samples were analyzed with chromatography and the results compared with those of plasma samples not exposed to MR fields. Thirty-four different amino acids were investigated and no significant changes were observed in the total concentration of any of them. Our results show that, at least in a cell-free system, exposure to a magnetic field at 0.5 T causes no significant quantitative changes in amino acid composition, at least no changes demonstrable at chromatography. On the other hand, our preliminary observation does not exclude that exposure to nonionizing radiation may modify in vivo enzyme kinetics with transient qualitative, but not quantitative, changes.

Adult↗
PubMed1996

Image acquisition. Sites, technologies, and approaches.

This article examines the current and future methodologies for image capture. Data conversion devices and systems, radiographic techniques of ionizing and nonionizing radiation, passive imaging, and digital image data requirements are explored. The author also discusses the problem of how to connect acquisition devices to PACS.

Analog-Digital Conversion↗
PubMed1998

Extremely low frequency electric and magnetic fields as risk factors in chemical industry.

OBJECTIVES: The risk assessment for staff in the chemical industry is usually related to accident hazards, production emergencies, blast and fire danger, or to the adverse effects of toxic substances. The combined effect of electric and magnetic fields with other factors combined with other hazards and working conditions, has not yet been studied. In all branches of industry, the members of staff who endure the most exposure to electric and magnetic fields, are electricians. This group is considered at high risk because of the increased probability of cancer. METHODS: We studied electric and magnetic fields with low frequencies in the nitrogen chemical fertilizer plant "HIMCO", Vratza. Sources of extremely low frequency fields (50 Hz) are local thermal power plants, substations, open (110 kV) and closed (6 kV and 0.4 kV) distribution devices, transformers, compressors and turbocompressors, command halls, and video display units. The methods used for assessing exposure of low frequency electric and magnetic fields were based on the separate measurement of the electric and magnetic components of the field, using spot measurements and evaluation of the real time duration of exposure for different staff groups. RESULTS: The measured values for the different staff groups were within the limits of national and international standards. The measured magnetic flux densities in the "HIMCO" plant exceeded 3 mG, a value which is considered by many investigations in the literature, as a possible carcinogenic factor. CONCLUSIONS: The prolonged exposure to low frequency electric and magnetic fields determines the place of these physical factors in the complex of hazardous environmental factors for the staff. The simultaneous performance of combined investigations of all risk factors would result in the complete risk assessment for staff in the chemical industry. Electricians are considered to be a professional group who have an increased risk of contracting cancer. Extensive measurement and assessment of exposure of the low frequency electric and magnetic fields is needed using individual dosimeters and retrospective analysis to determine this. It is important to study all types of nonionizing radiation in the whole of the Bulgarian chemical industry, especially within petroleum refineries.

Bulgaria↗
PubMed2002

Terahertz wave imaging: horizons and hurdles.

Terahertz (THz) science will profoundly impact biotechnology. It has tremendous potential for applications in imaging, medical diagnosis, health monitoring, environmental control and chemical and biological identification. THz research will become one of the most promising research areas in the 21st century for transformational advances in imaging, as well as in other interdisciplinary fields. However, terahertz wave (T-ray) imaging is still in its infancy. This paper discusses the uniqueness and limitations of T-ray imaging, identifies the major challenges impeding T-ray imaging and proposes solutions and opportunities in this field. It also concentrates on the generation, propagation and detection of T-rays by the use of femtosecond optics.

Crystallography↗
PubMed2002

The development of terahertz sources and their applications.

The terahertz region of the electromagnetic spectrum spans the frequency range between the mid-infrared and the millimetre/microwave. This region has not been exploited fully to date owing to the limited number of suitable (in particular, coherent) radiation sources and detectors. Recent demonstrations, using pulsed near-infrared femtosecond laser systems, of the viability of THz medical imaging and spectroscopy have sparked international interest; yet much research still needs to be undertaken to optimize both the power and bandwidth in such THz systems. In this paper, we review how femtosecond near-infrared laser pulses can be converted into broad band THz radiation using semiconductor crystals, and discuss in depth the optimization of one specific generation mechanism based on ultra-fast transport of electrons and holes at a semiconductor surface. We also outline a few of the opportunities for a technology that can address a diverse range of challenges spanning the physical and biological sciences, and note the continuing need for the development of solid state, continuous wave, THz sources which operate at room temperature.

Crystallography↗
PubMed1988

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

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.

Animals↗
PubMed1980

Effects of 2.45-GHz microwave radiation on embryonic quail hearts.

Although exposure to nonionizing electromagnetic radiation has been reported to cause a variety of systemic alterations during embryonic development, there are few reports of the induction of specific physiology or morphologic changes in the myocardium. This study was designed to examine the effects of microwave radiation on cardiogenesis in Japanese quail embryos exposed during the first eight days of development to 2.45-GHz continuous-wave microwaves at power densities of 5 or 20 mW/cm2. The specific absorption rates were 4.0 and 16.2 mW/g, respectively. The ambient temperature for each exposure was set to maintain the embryonated eggs at 37.5 degree C. This did not preclude thermal gradients in the irradiated embryos since microwaves may not uniformly absorbed. The test exposure levels did not induce changes in either the morphology of the embryonic heart or the ultrastructure of the myocardial cells. Analysis of the enzymatic activities of lactate dehydrogenase, glutamic oxaloacetic transaminase, and creatine phosphokinase failed to reveal any statistically significant differences between the nonexposed controls and those groups exposed to either 5 or 20 mW/cm2. The data indicate that 2.45-GHz microwave radiation at 5 or 20 mW/cm2 has no effect on the measured variables of the Japanese quail myocardium exposed during the first eight days of development.

Animals↗