Well, NIST is behind me and I'm enjoying a middle seat between to guys, neither of whom is a taking up more than their fair share of space. And with only 3 hours to go, it's time to pick up the AAMI conference where we left off.

The last session of the day was "RF Wireless in Healthcare (Part II)," presented by Eric Anderson and Dara McLain both with Philips. If you subscribe to the Biomed Listserv, you should recognize Dara's name from her significant listserv contributions about RF interference. (I got some snaps of her here and here.) It wasn't exactly clear, but I think that Eric and Dara are the RF interference tag team at Philips, with Eric working mostly in the lab and Dara playing Sherlock Holmes at customer sites solving crimes against medical RF applications. Given all the concern expressed in the previous session about interference in the 608 band of WMTS (not to mention the standing room only crowd) I was disappointed to see the sparse attendance for a session that talked about managing RF interference in hospitals.

Eric and Dara impressed the crowd with examples of past interference mysteries using RF spectrum tracings and sample photos. They also shared with the group their favored techniques for sussing out RF interference, and Dara demonstrated her preferred investigative tool, the Amritsu spectrum analyzer (photo here). The greatest source of radiated RF energy comes from known radiators, you know, transmitters and things like that. But, buy far the greatest source of RF interference that causes problems comes from unintentional sources - paper shredders (Rick Hampton's nemesis), hair dryers, florescent light ballasts, and numerous HVAC components.

In particular they talked about the importance of IEC60601-1-2 Ed.2.1 which is an EMC standard. The standard describes a prototypical RF interference scenario and then all the equipment that conforms to the standard has to measure the RF performance relative to the test. The test results allow you to compare the relative performance across different products. They recommended (strongly) that you ask for these results when your hospital buys anything that uses electricity.

While most radiated RF energy comes from intentional sources like transmitters and radios; the greatest source of interference that causes problems comes from unintentional radiators, like defective motors, switches and florescent light ballasts. Best practices include actively managing all the frequencies in use in your hospital, properly maintain all the electrical equipment in use, know and understand device or system susceptibility to interference (by using the IEC standard above), and perform RF site surveys - often. Surveys should be done annually, or when problems ocurr. They also recommend comparing surveys over time for potential problems. Eric closed the session with the sobering observation that, "everything we've seen could have been prevented."

In the following Q&A, the issue of cell phone interference was raised. (This seems to be a perennial issue on the Biomed Listserv.) Dara and Eric noted that they have found cell phones to be sources of interference in very rare occasions, and then only when the cell phone is placed close to the device. The bottom line was that cell phones are intentional RF radiators that need to be managed like anything else - banning them is a little extreme and not popular with either physicians or visitors.

Another end of session tidbit was the recommended source for keeping up with all these standards that should be part of your vendor selection and system maintenance processes. Eric's suggestion: Complaiance Magazine - sounds like scintillating reading.