Device specific standard test methods for electromagnetic interference of medical devices

Several device-specific, radiated electromagnetic interference test methods have been developed for particular combinations of medical devices and nearby sources of radio frequency interference (RFI). These tests are useful for supplementing the prevailing, generic standardized medical device RFI immunity test methods. Generic tests such as those specified IEC 601-1-2 and related standards underestimate the degree of RFI problems that can be encountered in the close proximity of handheld transmitters and cellular telephones. This occurs because the generic standards admittedly do not relate their test conditions to extreme exposure situations. Device-specific test methods have been developed by several organizations to evaluate the susceptibility to nearby transmitters of implantable cardiac pacemakers and defibrillators, as well as hearing aids. The U.S. Food and Drug Administration (FDA) developed and tested a "universal", simulated near-field RF source for this kind of test. It consists of a standard dipole antenna connected to an amplitude-modulated RF generator that can simulate a wide range of worst-case RF carrier frequencies and modulations. Another new device-specific test is the draft ASC 63 standardized test method for "ad-hoc" RFI testing. It is proposed to be used to evaluate the RFI susceptibility of a wide variety of specific medical devices. Individual RF sources will be used, such as handheld transmitters, placed one meter from the medical device under test in the actual clinical setting.