Diathermy Devices Research Articles

Evaluation of reproductive function of female rats exposed to radiofrequency fields (27.12 MHz) near a shortwave diathermy device.

In recent years, there has been increased concern regarding effects of operator exposure to the electromagnetic (EM) field associated with shortwave diathermy devices. The present study was designed to investigate the effects, on rats, of repeated exposure to such an EM field. Following repeated exposure for 5 wk, a reduction in fertility occurred as indicated by a reduced number of matings in exposed rats compared to sham-irradiated rats and a reduction in the number of rats that conceived after mating. The data suggest that female operators could experience reduced fertility, if they remained close to the console for prolonged periods. This has particular significant for the physiotherapy profession.

On the Safe Use of Microwave and Shortwave Diathermy Units

Diathermy is a common treatment modality used to relieve pain through localized heating. This paper briefly discusses the mechanisms through which heat is generated in tissue and the absorption characteristics of the applied electromagnetic radiation. The adverse effects of this radiation are reviewed with particular emphasis on the current exposure limits for operators and non-patients in the vicinity of diathermy devices. The newly introduced codes of practice for the 'Safe Use of Shortwave (Radiofrequency) and Microwave Diathermy' are also discussed.

Determination of Perfusion Field During Local Hyperthermia With the Aid of Finite Element Thermal Models

Two-dimensional transient thermal models of human thighs undergoing microwave diathermy are developed with the aid of experimental data to shed light on the blood flow response occurring during local hyperthermia in muscle. The experimental data were taken from tests on six human subjects treated with a 915-Mz, direct-contact microwave diathermy device which incorporated a system for simultaneously cooling the skin surface with a cold air stream. The numerically calculated perfusion fields were determined by systematically varying a model's blood flow response to the temperature stimulus until good agreement between the experimental and model temperature fields were achieved. The model blood flow values were then checked against those measured in the human experiments via xenon 133 washout and good agreement here was also found. The future use of models of this type in clinical diagnosis and hyperthermic treatment is proposed.

Measurements of electric and magnetic stray fields produced by various electrodes of 27‐MHz diathermy equipment

The present paper describes the results of measurements of electric and magnetic stray fields around three types of commercially available diathermy units with four very typical electrodes in six routine therapeutic treatments. The aim of the survey was to investigate the exposure to the physiotherapist and the exposure to unprescribed tissues. Field strengths were measured at 15 points close to the patient's body. At a distance of 0.6 m from the diathermy units the power density was less than 10 W/m2. With respect to stray fields the results showed that the diathermy devices are very similar but there are great differences between the electrodes during specific treatments. The results assist in selecting proper electrodes for various therapeutic treatments, as they indicate which electrodes would have minimal stray fields.

United States radiation safety and regulatory considerations for radiofrequency hyperthermia systems.

The control of Radiofrequency (RF) radiation (including microwave radiation) that is emitted by therapeutic medical devices is the responsibility of the Food and Drug Administration's (FDA) Bureau of Radiological Health (BRH). Several studies of RF emissions from various shortwave (27 MHz) and microwave (2450 MHz) diathermy devices have been conducted by the Electromagnetics Branch of the Bureau's Division of Electronic Products. BRH studies have led to a proposed standard for microwave diathermy devices operating above 900 MHz. Shortwave diathermy devices used in physical therapy situations have been found to produce relatively high levels of unintended exposures (sometimes exceeding present U.S. exposure standards) to device operators and to the nonprescribed tissues of the patient. BRH is initiating further studies to ascertain the need for controls to be placed on these shortwave devices to ensure safety and medical effectiveness. Radiation safety standards, which presently exist in the United States, allow much higher unintended human exposures than do the standards existing in the several eastern European countries. A trend to lower permissible exposures to 5 mW/cm2 or even 1 mW/cm2 is under way in the U.S. The various provisions of FDA's Medical Device regulations apply to investigational as well as commercially-marketed RF/microwave devices and require both safety and medical effectiveness aspects of performance to be addressed by their manufacturer. A set of microwave radiation safety considerations has been developed by BRH for newly emerging cancer therapy protocols which utilize microwave hyperthermia devices.

Application of the iKnife for the Enhanced Identification of Cancerous Tissue in Breast Surgery

Improved tumour margin detection in breast surgery is required to reduce cancer recurrence and to minimize the amount of tissue removed. Rapid evaporative ionization in mass spectrometry (REIMS) pair s the surgical diathermy device directly to a mass spectrometer to analyze the lipid components in the surgical aerosol. This intelligent knife, or iKnife, has the potential to provide surgeons with real-time characterization of healthy versus cancerous tissue.Objective: To show that healthy and malignant breast tissue can be differentiated by REIMS using coagulation and cut diathermy modes.Methods: 83 patients were recruited at Charing Cross Hospital. 76 normal and 44 tumour samples were cut using a surgical diathermy handpiece and the aerosol was analyzed by mass spectrometry and confirmed by histology. Multivariate statistical analyses were used to evaluate the data.Results: In cut mode, the data demonstrates 95.1% correct classification of healthy and tumour samples, with a sensitivity of 91.9% and a specificity of 95.9%. In coagulation mode, the data revealed93.5% correct classification of healthy and tumour samples, with 89.3% sensitivity and 94.1% specificity.Conclusions: This preliminary data suggests the iKnife can distinguish between healthy and malignant tissue ex vivo with the potential to provide intraoperative feedback to surgeons.

Antennas for radiation measurements

RADIATION from diathermy, electronic heating, and other industrial devices is now subject to federal regulation. There is no commercial equipment available that is suitable for measuring electromagnetic fields at frequencies above 400 megacycles per second. The present procedure is to use the receiver-signal generator substitution method. This requires the use of a pickup device of known characteristics.