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At least 145 records · Page 8Linked to original sources

PubMed1984

Clinical diaphanography--its present perspective.

The application of nonionizing radiations and magnetism in clinical medical diagnosis has been rapidly increasing. The incorporation of these techniques into the armamentarium of the diagnostic roentgenologist warrants a change in nonmenclature to diagnostic imageologists. This review of the clinical applications of diaphanography covers the period of simple light source examination of the 1930s to the present sophisticated imaging with infrared film or videcon T.V. computerized format. Light physics of the infrared spectrum is well known, however experimental data of the mechanism of transillumination or normal and abnormal breasts are being investigated. A short discussion of breast anatomy and pathology including benign and malignant is basic to the clinical evaluation technique. A realistic appraisal of the application, the limitations of the technique and the current ongoing investigative studies in the European and American literatures are reviewed. Other noninvasive breast diagnostic techniques of thermography, ultrasound, and NMR are included as well as mammography in the diagnosis of breast disease and cancer.

Breast↗

PubMed1999

Ultrasonically guided inferior vena cava stent placement: experience in 83 cases.

PURPOSE: Traditionally, inferior vena cava (IVC) stent placement is performed with fluoroscopic guidance. The object of this study was to evaluate use of ultrasound (US) as guidance for IVC stent placement for the management of Budd-Chiari syndrome. MATERIALS AND METHODS: Eighty-three patients with IVC membranous stenosis (n = 30), membranous occlusion (n = 19), segmental stenosis (n = 21), or segmental occlusion (n = 13) underwent IVC recanalization, balloon dilation, and stent placement under US guidance. Among the 83 patients, 67 had at least one patent hepatic vein, while 16 patients had three occluded hepatic veins. RESULTS: IVC stents were successfully placed in 79 of 83 patients, with a success rate of 95%. After the procedure, the symptoms and signs of IVC obstruction disappeared or markedly improved in all patients, and the blockage of hepatic outflow was alleviated in 67 patients. Pericardial effusion, complete atrial ventricular block, and stent migration into the right atrium occurred, respectively, in one patient. During 1-46-month follow-up, stent restenosis occurred in one patient; the other stents remained open and functioned effectively. CONCLUSION: Because of the absence of nonionizing radiation and iodinated contrast material, and its low cost, US is well suited and often preferred for guidance of IVC stent placement.

Adolescent↗

PubMed2003

Performance of quantitative ultrasound in the discrimination of prevalent osteoporotic fractures in a bone metabolic unit.

There is a growing interest in ultrasound evaluation of bone status as an alternative to the measurement with dual X-ray absorptiometry (DXA), due to its low cost, portability, and nonionizing radiation. The aim of our study was to investigate the relation among DXA, QUS, clinical, anthropometric, and lifestyle factors, and to determine QUS cutoff values in order to discriminate fractures in patients referred to the Bone Metabolic Unit at an Endocrinology Service. We studied 300 patients (281 females and 19 males; age 58 +/- 11 years) referred for evaluation of osteoporosis. In all cases we determined basic anthropometric parameters, a clinical history including previous osteoporotic fractures and risk factors for osteoporosis, and QUS parameters in calcaneus (Hologic Sahara), and BMD in lumbar spine (LS) and femoral neck (FN), by DXA (Hologic QDR 1000). Using the WHO densitometric criteria, 37, 46.7, and 16.3% of our population were osteoporotic, osteopenic, and normal, respectively. A QUI T-score </=-1.5 SD provided a sensitivity of 68.9% and a specificity of 64.7% for osteoporotic fracture discrimination and a sensitivity of 64.9% and a specificity of 74.1% for osteoporosis defined by WHO criteria using DXA. In the logistic regression, the presence of family history of fragility fractures (OR: 3.03; CI 95%: 1.3-7.03), a DXA T-score </=-2.5 (OR: 3.58; CI 95%: 1.66-7.73), and a QUI T-score </=-1.5 (OR: 2.56; CI 95%: 1.15-5.69) were independently associated with prevalent osteoporotic fractures. In conclusion, calcaneus ultrasound appears as a useful technique for the routine clinical practice, as its performance is similar to DXA for the discrimination of subjects with osteoporotic fracture.

Absorptiometry, Photon↗

PubMed1984

Nd-YAG laser therapy for tracheobronchial disorders.

The neodymium-yttrium aluminum garnet (Nd-YAG) laser has demonstrated its effectiveness in treatment of a number of benign and malignant tracheobronchial disorders. This laser has many advantages over past methods of endobronchial therapy, such as cryosurgery and electrocautery. It is a precise, no-touch method that produces little pain during therapy and little or no edema or infection afterward. Since the laser is a form of nonionizing radiation, therapy may be repeated as often as needed. Unlike the carbon dioxide laser, the Nd-YAG laser may be used with standard flexible endoscopes. Currently, the commonest indication for Nd-YAG laser therapy is obstruction of a large airway by an inoperable neoplasm. Whether this technique can be applied more widely in management of early lung cancer, possibly in combination with radiotherapy, chemotherapy, or surgery, will be determined by further study.

Airway Obstruction↗

PubMed1991

Hazard assessment of video display units.

This report describes the results of a study of potential health hazards of video display units (VDUs). The specific elements of the study included characterizing the emissions of ionizing and nonionizing radiation and exposures to electromagnetic fields. There was no evidence that operators are exposed to electric, magnetic, or ionizing radiation fields significantly above ambient levels. Significant x-ray leakage cannot occur under any credible conditions. In addition to the ergonomic aspects of VDU work, reports on the health aspects of VDU operators were investigated. The results of the study, based on the specific hazards evaluated, do not support allegations that VDU operation is hazardous beyond the identified transient discomforts associated with characteristics of the work performed. A high-profile employee education program was initiated to minimize discomforts and unwarranted concerns.

Air Pollutants, Radioactive↗

PubMed1988

Acute nonlymphocytic leukemia and residential exposure to power frequency magnetic fields.

Recent research has suggested that nonionizing radiation in the form of power-frequency magnetic fields may play some role in carcinogenesis in general and in acute nonlymphocytic leukemia in particular. Much of the epidemiologic evidence is preliminary in nature and the methods of previous studies have been criticized. In order to further evaluate this hypothesis, a population-based case-control study of adult acute nonlymphocytic leukemia and residential exposure to power-frequency magnetic fields was carried out in western Washington state. Analyses were based on 114 cases who were newly diagnosed from 1981 to 1984 and identified from a population-based cancer registry, and 133 controls who were chosen from the study area by random digit dialing. Magnetic field exposure was estimated from external electrical wiring configurations within 140 ft (42.7 m) of each subject's residence. In addition, magnetic fields were measured inside the subject's residence at the time of interview. Neither the directly measured magnetic fields nor the surrogate values based on the wiring configurations were associated with acute nonlymphocytic leukemia.

Acute Disease↗

PubMed1988

Case-control study of childhood cancer and exposure to 60-Hz magnetic fields.

Concern with health effects of extremely low frequency magnetic fields has been raised by epidemiologic studies of childhood cancer in relation to proximity to electric power distribution lines. This case-control study was designed to assess the relation between residential exposure to magnetic fields and the development of childhood cancer. Eligible cases consisted of all 356 residents of the five-county 1970 Denver, Colorado Standard Metropolitan Statistical Area aged 0-14 years who were diagnosed with any form of cancer between 1976 and 1983. Controls were selected by random digit dialing to approximate the case distribution by age, sex, and telephone exchange area. Exposure was characterized through in-home electric and magnetic field measurements under low and high power use conditions and wire configuration codes, a surrogate measure of long-term magnetic field levels. Measured magnetic fields under low power use conditions had a modest association with cancer incidence; a cutoff score of 2.0 milligauss resulted in an odds ratio of 1.4 (95% confidence interval (CI) = 0.6-2.9) for total cancers and somewhat larger odds ratios (ORs) for leukemias (OR = 1.9), lymphomas (OR = 2.2), and soft tissue sarcomas (OR = 3.3). Neither magnetic fields (OR = 1.0) nor electric fields (OR = 0.9) under high power use conditions were related to total cancers. Wire codes associated with higher magnetic fields were more common among case than control homes. The odds ratio to contrast very high and high to very low, low, and buried wire codes was 1.5 (95% CI = 1.0-2.3) for total cases, with consistency across cancer subgroups except for brain cancer (OR = 2.0) and lymphomas (OR = 0.8). Contrasts of very high to buried wire code homes produced larger, less precise odds ratios of 2.3 for total cases, 2.9 for leukemias, and 3.3 for lymphomas. Adjusted estimates for measured fields and wire codes did not differ from crude results, indicating an absence of confounding. Limitations to the study are nonresponse (especially for field measurements), differential mobility of cases and controls, and a presumably nondifferential exposure misclassification from the use of imperfect surrogates for long-term magnetic field exposure history. In spite of these concerns, the results encourage further examination of the carcinogenic potential from this form of nonionizing radiation.

Adolescent↗

PubMed1999

Evaluation and validation of ureteric jet index by glomerular filtration rate.

RATIONALE AND OBJECTIVES: Ureteric jet index (UJI), a newly developed technique derived from color Doppler ultrasonography, may hold promise in evaluating renal function because of its ability to evaluate individual renal function and the use of nonionizing radiation. To assess the usefulness of UJI, the authors in this study analyzed the relation between UJI and the glomerular filtration rate (GFR). METHODS: Fifteen adult patients with a wide range of renal function were included in this study. Subjects were well hydrated before color Doppler ultrasonography examinations. The UJI formula was: Vmean (average jet velocity) x D (jet duration) x F (jet frequency). GFR was calculated by the radionuclide method. Correlations between UJI, serum creatinine, and GFR were analyzed. RESULTS: Ureteric jet index had only a fair correlation with GFR. The coefficient of correlation value was 0.61, and the standard error of estimate of GFR was 17.9 mL/min. CONCLUSIONS: With the measurement of UJI, color Doppler ultrasound can provide both structural images and individual renal function information. It could substitute for a renal scan in determining individual renal function when a radionuclide examination is unavailable. Even if a renal scan were available, UJI can play a valuable role in the ultrasound examination of patients with suspected impaired renal function, providing further assessment of individual renal function.

Adult↗

PubMed1997

Utility of ultrasound to assess risk of fracture.

Traditional assessments of bone properties have utilized densitometry techniques such as Dual Energy X-ray Absorptiometry (DXA). Recently, quantitative ultrasound (QUS) has been introduced as an alternative method of assessing bone properties. Advantages of QUS over X-ray techniques include low costs, portability, and nonionizing radiation. Proponents of QUS have claimed that this technology can provide information not only about the density but also about the structure and mechanical properties of bone. There are two major questions that need to be answered for those who seek to diagnose bone disorders with ultrasound: (1) what does quantitative ultrasound actually measure, and, even more importantly, (2) what is its clinical utility? In this review we will briefly examine the first question and will focus on the utility of ultrasound in clinical trials to discriminate between fractures and non-fractures and to predict the risk of fractures.

Adult↗

PubMed1993

A cluster of brain tumours in a New South Wales colliery: a problem in interpretation.

Following the reporting of a cluster of cases of brain tumour in the workforce of an underground coal mine (Mine A) in the Newcastle coalfield, a study was carried out to determine whether this phenomenon was due to chance alone or whether an environmental cause could be postulated. The study design was a historical cohort study over 15 years comparing the incidence of brain tumour (ICD9 191 and 192) in the index mine with that in two control mines (Mines B and C) in the same area and with that in the general Australian population. We compared environmental exposures (ionising and nonionizing radiation and chemical exposure) in the three mines. With Australian brain tumour incidence rates as reference, the standardised incidence ratio for brain tumour in Mine A was 5.3 (95 per cent confidence interval (CI) 1.08 to 14.04) and in Mines B and C combined was 1.23 (CI 0.02 to 3.80). On most environmental assessments the three mines were similar but Mine A used larger volumes of solvents than the other mines. This study poses two questions: was the increase in cases of brain tumour in Mine A 'real' and if so, was it related to the use of solvents? Data, from an investigation of a cluster such as this, are unlikely to be conclusive. Nevertheless, such answers are demanded not only by those at risk but also by the mine management, which is responsible for a safe working environment. Some of the difficulties involved with this judgment are discussed.

Adult↗

PubMed2004

Classification of breast tissue density by optical transillumination spectroscopy: optical and physiological effects governing predictive value.

Preventive oncology is in need of a risk assessment technique that can identify individuals at high risk for breast cancer and has the ability to monitor the efficacy of a risk reducing intervention. Optical transillumination spectroscopy (OTS) gives information about breast tissue composition and tissue density. OTS is noninvasive and in contrast to mammography, uses nonionizing radiation. It is safe and can be used frequently on younger women, potentially permitting early risk detection and thus increasing the time available for risk reduction interventions to assert their influence. Before OTS can be used as a risk assessment and/or monitoring technique, its predictive ability needs to be demonstrated and maximized through the construction of various mathematical models relating OTS and breast tissue density, and hence, risk. To establish a correlation between OTS and mammographic density principal components analysis (PCA), using risk classification, is calculated. The PCA scores are presented in three-dimensional cluster plots and a plane of differentiation that separates the high and low tissue densities is used to calculate the predictive value. Stratification of PCA for measurement position on the breast in cranial-caudal projection is introduced. Analysis of PCA scores as a function of the volunteer's age and body mass index (BMI) is examined. A small but significant correlation between the component scores and age or BMI is noted but the correlation is dependent on the tissue density category examined. Correction of the component scores for age and BMI is not recommended, since a priori knowledge of a woman's breast tissue density is required. Stratification for the center and distal measurement positions provide a predictive value for OTS above 96%.

Adult↗

PubMed2004

Electromagnetic breast imaging: average tissue property values in women with negative clinical findings.

Representative data are provided for three electromagnetic breast imaging techniques-near-infrared spectroscopy, electrical impedance spectroscopy, and microwave imaging spectroscopy-to serve as potential benchmarks for future investigation. The breasts of 23 women without clinical or mammographic findings of disease were imaged in the coronal plane with nonionizing radiation of varying frequencies. Average electromagnetic property values were reconstructed at each frequency on the basis of computational models of light diffusion, current flow, and microwave propagation. Electromagnetic properties were correlated with subject characteristics and between techniques. Each technique yielded information on breast tissue features (eg, conductivity, permittivity, light scattering, and absorption) that had not previously all been measured in the same individuals.

Adult↗

PubMed2004

Detection of primary lung tumors in rodents by magnetic resonance imaging.

This report describes recent efforts to develop and apply small animal magnetic resonance imaging methods to the study of lung tumors in mice. Magnetic resonance (MR) images obtained with respiratory gating, with data collection synchronized with the respiration of the animal, allow visualization of submillimeter tumors in animals treated with a lung carcinogen. Comparison of the MR images with gross pathology of these lungs demonstrates the utility of the imaging methods for measuring tumor burden. As a noninvasive imaging modality that uses nonionizing radiation, MR is well suited to longitudinal studies aimed at understanding the factors that control the onset and development of lung tumors and their response to therapy in a wide variety of animal models.

Animals↗

PubMed1995

Water loss from the skin of term and preterm infants nursed under a radiant heater.

The rate of evaporation from the skin (g/m2/h) was measured in 12 full-term and 16 preterm infants (gestational age 25-34 wk) both during incubator care and when nursed under a radiant heater. The method for evaporation rate measurement is noninvasive and based on determination of the water vapor pressure gradient close to the skin surface. Measurements were first made with the infant nursed in an incubator with a controlled environment with respect to humidity, temperature, and air velocity. The measurements in the term infants were performed at an ambient relative humidity (RH) of 50%, and in the preterm infants first at 50% and subsequently at 30-40%. Evaporation rate was then measured with the infant nursed under a radiant heater. In term infants, mean evaporation rate was 3.3 g/m2/h during incubator care (RH 50%) and 4.4 g/m2/h during care under the radiant heater. In preterm infants, the corresponding values were 15.5 g/m2/h in the incubator at RH 50%, 16.7 g/m2/h at RH 30-40%, and 17.9 g/m2/h under the radiant heater. It is concluded that the evaporative water loss from the skin depends on the ambient water vapor pressure, irrespective of whether the infant is nursed in an incubator or under a radiant heater. The higher rate of evaporation during care under a radiant heater is due to the lower ambient water vapor pressure and not to any direct effect of the nonionizing radiation on the skin.

Air↗

PubMed1996

Is sperm motility maturation affected by static magnetic fields?

Kinematic parameters were evaluated in mouse epididymal extracts to monitor maturation of sperm movement in animals exposed to static magnetic fields using the Sperm-Class Analyzer computerized image analysis system. For this purpose, animals were exposed to a field of 0.7 T generated by a permanent magnet over 10 or 35 days for either 1 or 24 hr/day. The values of the motion endpoints were similar in animals used as controls and in those exposed to the nonionizing radiation, whatever the period of exposure or daily dosage. Changes in motility were observed in all groups: the percentage of total motile and progressive motile spermatozoa increased during passage through the epididymis, with major changes between the caput and corpus epididymides, and the pattern of swimming changed clearly towards more rapid and straighter trajectories. The processes of initiation of sperm motility and maturation of displacement patterns were not then affected by magnetic treatment. Moreover, it appears that sperm production is unaffected because no changes were observed in testicular or epididymal weights after exposure to static magnetic fields.

Animals↗

PubMed1984

Biophysical aspects of corneal and lenticular transparency.

The chemical composition and morphology of the cornea and lens can provide significant information regarding what wavelengths of nonionizing radiation these two tissue should absorb and transmit. Such data, including a variety of parameters determined by biophysical techniques, can provide us with information regarding the molecular basis for corneal and lenticular transparency and the subtle changes occurring with aging and ambient radiation exposure during our lifetime. The biophysical approach (fluorescence and NMR spectroscopy) has already provided new clinical tools for studying and delineating the initial events responsible for eventual opacification in these two tissues, months to years before they become manifest by current conventional clinical methods of examination.

Animals↗

PubMed1992

Some perturbations that disturb the circadian melatonin rhythm.

The circadian melatonin rhythm is highly reproducible and generally not easily altered. The few perturbations that are capable of significantly changing either the amplitude or the pattern of the 24-h melatonin rhythm are summarized herein. Aging alters cyclic melatonin production by decreasing the amplitude of the nocturnal melatonin peak in all species in which it has been studied. The best known acute suppressor of nocturnal melatonin is light exposure. The brightness of light required to acutely depress pineal melatonin production is species dependent; of the visible wavelengths, those in the blue range (approximately 500-520 nm) seem most effective in suppressing melatonin production. Nonvisible, nonionizing radiation in the extremely low frequency range (e.g., 60 Hz) seems also capable of altering pineal melatonin synthesis. Hormones have relatively little influence on the circadian production of melatonin, although either adrenalectomy or hypophysectomy does attenuate the amplitude of the melatonin cycle. Exercise at the time of high melatonin production rapidly depresses pineal concentrations of the indole without influencing its synthesis; the mechanism of this suppression remains unknown.

Aging↗

PubMed2000

[Cellular radio systems. Problems faced in assessing exposure to electromagnetic fields].

Over twenty years of its existence, cellular radio systems have become one of the major sources of human exposure to electromagnetic field (EMF) of high frequency. With the increasing number of cellular phones, the interest in health effects of exposure to EMF emitted by them continues to grow. At present, there is a general opinion that thermal effect (change of electromagnetic energy into thermal energy) is an essential mechanism of possible biological effects. The majority of world standards for exposure to EMF are based on this effect. The author presents Polish standards and those of the International Commission on Nonionizing Radiation Protection (ICNIRP) for EMF of frequencies used in cellular radio systems, both basic that limits SAR (Specific Absorption Rate), and derived that limits the power density, as well as intensity of electric and magnetic fields. Attention was also turned to the problems concerning the application of cellular phones and those resulting from the character of the field emitted by them to which their users are exposed. Bearing in mind the results of the laboratory analyses of SAR values occurring in the user's head, and measurements of power density in the vicinity of the base station antennas, it can be stated that, in view of binding and recommended standards, cellular phones do not present any hazard to their users (private or professional). However, it should be stressed that standards adopted protect the user's head against the thermal effect, whereas the question on whether they also protect against non-thermal effects still remains without answer.

Electromagnetic Fields↗