IIRC, the NMR specifically operates by producing a change in the patient's body (albeit on a molecular level). The sharp power pulse knocks the molecules off of their spin axis(?). As the molecules try to recover their original alignment, precession induces a wobble, which creates the tiny RF signature that is characteristic of the individual molecules. The RF signal is processed and the image created.
Sounds to me like the energy is "external" to the equipment, even if it isn't very far. And it certainly appears to me that the process fits the definition of "treatment of a material". To make a flambouyant analogy; you can stare at a steel beam, weigh it, measure it's dimensions, etc. You may be able to calculate it's mechanical resonant frequency. But if you walk up and whack it with a hammer, you have just "treated the material." --- On Wed, 01 Jul 1998 17:09:30 GMT Patrick Lawler <[email protected]> wrote: > For those of you who haven't seen one, an NMR is a machine that uses RF energy > to scan patients, who slide (almost entirely) into a hole inside the machine. > The hole has an RF transmitting and receiving antenna. > If the energy stays within the scanning 'hole', and within the outside > boundaries of the machine, is the energy still considered 'internal' to the > equipment? > Or is the fact that the system has an RF antenna beaming energy into the hole, > mean that the energy is 'external' to the machine.? > > > On Wed, 1 Jul 1998 07:58:07 -0600, "Lyle Luttrell" <[email protected]> > wrote: > >In classification for CISPR 11, one should consider whether the RF > >energy is intended to perform a function related to the intended use of the > >device. For Group 1 the RF energy is "necessary for internal functioning > >of the equipment ", which implies that any external RF radiation would be > >unintentional. While the Group 2 definition specifies "treatment of > >material", it can be appropriate in many other cases where RF energy is > >intentionally generated to perform the equipment function. For an NMR > >diagnostic device, I think that a good case can be made that the device > >should be Group 2. > > > >Lyle Luttrell > >Luttrell & Associates > > > >-----Original Message----- > >From: [email protected] <[email protected]> > >To: [email protected] <[email protected]> > >Date: Tuesday, June 30, 1998 11:47 AM > >Subject: NMR device classification > > > > > >> > >> > >> > >>We have some trouble about the classification according to CISPR 11 of a > >>diagnostic NMR device. In my opinion the radio frequency energy is NOT > >>genereted for treatment of material (human body). This condition applies > >>only to therapy equipment that produce some change in the body. For that > >>reason this is a group 1 device. Someone else disagree with me, of course. > >>Does anybody have any opinion or experience about the matter?. > >>Thanks. > >>------------------------------------------------------- > >>ESAOTE S.p.A. Massimo Polignano > >>Research & Product Development Regulatory Affairs > >>Via di Caciolle,15 tel:+39.055.4229402 > >>I- 50127 Florence fax:+39.055.4223305 > >> e-mail: [email protected] > >> > > > > > > > > -- > Patrick Lawler > [email protected] > ---------------End of Original Message----------------- -------------------------- Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: [email protected] Date: 07/01/98 Time: 13:03:28 --------------------------
