Measurements of Emission Levels during Microwave and Shortwave Diathermy Treatments

摘要

Shortwave and microwave diathermy treatments are used to relieve pain through the noninvasive application of electromagnetic energy to body tissues. In administering these treatments, not all of the energy is confined to the treatment area. This 'stray' radiation exposes unintended tissue of the patient and also can expose the operator (physical therapist, coach, and so forth). This study was conducted to quantify the exposure levels experienced by the operator during diathermy treatments. For the three microwave units surveyed, with the operator standing at the controls of the diathermy console, the maximum measured power density was 1.3 mW/sq cm (equivalent to 70 V/m and 0.19 A/m in free space). For the six shortwave units surveyed, with the operator standing at the controls of the diathermy console, the maximum measured fields strengths were 0.47 A/m and 250 V/m (equivalent to free-space power densities of 8.3 mW/sq cm and 16.6 mW/sq cm). If the operator moved closer to the applicator during the treatment, the exposures would be much higher. This survey indicated a need for suppression of unnecessary radiation from the applicators of microwave diathermy units, and from the applicators and cables of shortwave diathermy units.