United States Radiation Safety and Regulatory Considerations for Radiofrequency Hyperthermia Systems

Abstract

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 at 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 (sometimeexceeding present U.S. exposure standards) to device operators and to the nonprescribed tissues ofthe Pattent.BRH ids initiating further studies to ascertain the need for controls to be placed onthese 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.