IEEE - ANSI C63.18
Recommended Practice for an on-Site, Ad Hoc Test Method for Estimating Electrimagnetic Immunity of Medical Devices to Radiated Radio-Frequency (RF) Emissions from RF Transmitters
|Publication Date:||1 January 2014|
This recommended practice is a guide to evaluating the electromagnetic immunity of medical devices to radiated radio-frequency (RF) emissions from common RF transmitters (e.g., two-way radios; walkietalkies; mobile phones; wireless-enabled tablets, e-readers, laptop computers, and similar devices; radiofrequency identification (RFID) readers; networked mp3 players; two-way pagers; and wireless personal digital assistants [PDAs]). This protocol does not provide a comprehensive test or offer any guarantee, but it is a basic evaluation that can help identify medical devices that might be particularly vulnerable to interference from common RF transmitters. The ad hoc test protocol can be used to evaluate existing or newly purchased medical devices or can be implemented for the purpose of prepurchase evaluation. This recommended practice applies to medical devices used in health-care facilities, but it can also be adapted to medical devices in home health-care or mobile health-care settings. It does not apply to implantable medical devices (e.g., pacemakers and defibrillators), transport environments such as ambulances and helicopters, or RF transmitters rated at more than 8 W of output power. Testing with transmitters greater than 8 W in health-care facilities is not recommended because of possible adverse effects on critical-care medical devices that are in use in nearby areas of the facility. Finally, this recommended practice does not address in-band RF interference where the fundamental frequency of an RF transmitter overlaps with frequencies used by a hospital wireless network or monitoring or used by other medical device wireless links.
The purpose of this recommended practice is to provide an ad hoc test method to estimate the electromagnetic immunity of medical devices and help identify interference issues that might exist with critical medical devices as a result of emissions from RF transmitters increasingly used in health-care facilities, particularly by doctors, staff, patients, and visitors. RF transmitters include two-way radios, walkie-talkies, mobile phones, wireless-enabled laptop computers and similar devices,1 RFID readers, networked mp3 players, two-way pagers, wireless PDAs, and wireless medical devices. The test protocol is designed to be performed as follows:
a) By clinical engineers, biomedical engineers, and other technical personnel
b) In a way that is relatively rapid and practical
c) In an area and with equipment that are commonly available
d) To identify specific effects and thresholds (i.e., transmit power and distance) to provide the basic information needed to develop a mitigation action plan
e) To generate test results that can be used in the formulation of policies and procedures for managing the use of RF transmitters within a health-care facility
A preferred method (5.6.2) and several alternative RF sources and methods (Annex C) for ad hoc testing are outlined in this recommended practice to allow flexibility with regard to the time, personnel, and resources available to perform the testing. As a result, these different options provide different levels of accuracy and comprehensiveness. The most appropriate ad hoc test strategy will depend on the needs and resources of the user of this recommended practice. This recommended practice also provides guidance for selection of the medical devices to be tested, operation of RF transmitters used as RF test sources, and assessment of test results.
The preferred method for evaluation in most circumstances
involves the use of the actual RF transmitter(s) (e.g., mobile
phones and portable and mobile radios) as test sources to generate
the same RF signals that would be encountered in the health-care
facility. This approach also assumes that the end user has limited
time and resources, a small number of critical medical devices to
test, a limited space in which to perform the testing, and a single
or a small number of specific RF transmitter signals to examine. In
this preferred method, the RF transmitter is placed in a constantly
transmitting state (i.e., test mode). The tests can be performed
with or without an electric-field-stren
Another important function of this recommended practice is to define a consistent test protocol to allow results to be obtained and compared within and across institutions. Clinical and biomedical engineers have methodology, RF transmitter sources, and medical devices. As a result, a comparison of the findings between health-care organizations might not be appropriate. To facilitate a comparison between health-care organizations, it is important that the recommendations herein are followed, deviations are kept to a minimum, and the testing is performed as consistently as possible.
Policies and procedures for mitigation of electromagnetic interference (EMI)2 in health-care facilities, including the use or restriction of specific RF transmitters within specific areas, often called an exclusion zone, should be based on objective information, including that obtained by the use of this test method. A common problem with exclusion zones is that they are difficult to enforce, particularly with the increasingly common use of wireless devices and their expanding variety of applications, including use in medical equipment. With regard to purchase evaluation, confirming that medical devices conform to voluntary EMC immunity standards can provide some information, although many RF transmitters are able to exceed these immunity levels greatly when held close to a medical device. This recommended practice can be used to supplement the information obtained by testing for conformance to voluntary EMC standards. A list of EMC standards and guidelines that contain radiated RF immunity requirements applicable to medical devices as well as additional background information and further recommendations for mitigation of EMI in health-care facilities are presented in the annexes.
1 As of the publication of this recommended practice, examples of wireless-enabled devices that comply with IEEE 802® technology were commonly referred to as Wireless Local Area Network-wLAN (WiFi®), Wireless Personal Area Network-wPAN (Bluetooth®, ZigBee®, XBee®), Wireless Metropolitan Area Network-wMAN (WiMAX®), and Wireless Regional Area Network- wRAN. This information is given for the convenience of users of this standard and does not constitute an endorsement by the IEEE of any trademark or trademark owner. Trademarks are the property of their owners. Other trademarks that are equivalent to those listed may be used to identify wireless technology based on IEEE 802 technology.