I was privileged enough as a young child to have parents who cared vigorously for my health. I was less privileged that their care for my health included care for my teeth, and the expression of that care was two visits to the dentist every year. I’m just kidding about that not being a privilege, of course. But I can’t think of anyone who looks forward to visits to the dentist’s office, unless that person is a dentist. One of my least favorite experiences at the dentist’s office is the oral X-ray. I don’t so much mind the idea of being irradiated, but I can’t stand the plastic thing they make you stick in your mouth. It’s sharp and never seems to fit right. I wish it didn’t involve anything other than the lead vest.

Thinking about that lead vest got me to thinking about the differences between the radiation generated by dental X-ray machines and electromagnetic interference. I remember learning in science class that radiation is radiation; X-rays are just at a different wavelength than the electromagnetic radiation that causes interference. Perhaps this is why, when shielding me from X-rays, a lead vest is needed, and when shielding a cable from EMI, just a few layers of shielded foil are needed. X-rays penetrate surfaces more easily than lower-frequency electromagnetic radiation. The expression “desperate times call for desperate measures” seems to apply here: there isn’t much ambient X-ray activity, and it usually doesn’t get generated by man-made sources accidentally. We don’t use lead vests to shield things from EMI because it usually isn’t necessary. Only in the context of extremely sensitive electronic devices are heavy-duty shielding materials like lead necessary. Otherwise, there is a wide variety of other lighter-duty materials that can be used as EMI shielding utilities.