Looking for answers,and recommendations for cabling ina building with six MRI machines ,and other medical imaging machines,They have limited space for cable paths in the ceiling ,and in the past it appears because of the difficulty several cables were placed with no regard for standards even when obtainable. Would sheilded cable contribute ,or create more problems because of the strong magnetic field. Your expertise and opinions appreciated.
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strong magnetic field effects on network cabling 3
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Servamatic
IS-IT--Management
Let me preface with I have never actually wired or cabled an MRI area in a hospital, but I have worked on several.
Everything I have ever seen in a hospital is in conduit due to codes. Metallic conduit is the best shield you can install generally speaking.
I will be curious to hear from those that have actually cabled in an MRI area though.
Richard S. Anderson, RCDD
Everything I have ever seen in a hospital is in conduit due to codes. Metallic conduit is the best shield you can install generally speaking.
I will be curious to hear from those that have actually cabled in an MRI area though.
Richard S. Anderson, RCDD
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Thanks for the response Servamatic,This may sound dumb ,but my thoughts seem to question if metal being a sheild or conduit might tend to induce a magnetic field,sheild and grounds drain foreign voltage ,Does magnetic fields act the same way? My tendencies would be to isolate the cables as far as possible from the field,and I would think fiber might be the best solution,but an exspense I'm not sure they will accept.Thanks again ,and am looking forward to more insightful postings.
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daronwilson
Vendor
We've done two MRI units in the hospital we service, in those we had all the wiring in conduit inside the room. Once in the hallway of the hospital it drops into cable tray, there is no code requirement that I am aware of for it to remain in conduit. We've not experienced any issues with the data or telephone wiring.
We also have done several mobile MRI trailers, the cabling inside the trailer is generally routed and provided by the MRI machine manufacturer to an interface point on the bottom of the trailer. In hooking them up, we've followed the cables inside, and found them not to be in metalic conduit.
The last MRI trailer we did, we ran fiber out to the pedestal due to the distance the unit was from the hospital building. In the pedestal we have a fiber optic transceiver and it is Cat6 to the trailer for the data. We've been very pleased with the marinco marine telephone jacks and plugs for phone, and the Seimons industrial ethernet connectors for data. It rains so much here, this stuff is pulled in and out of service twice or three times a week with no water trouble.
If it were an issue, I would still think the most immunity would be provided with a grounded metallic conduit. However, your best resource may be the manufacturer of the equipment. When we wire these units up for power, the manufacturer provides complete details for the entire room, and generally a tech is available with the equipment to answer questions.
Good Luck!
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
We also have done several mobile MRI trailers, the cabling inside the trailer is generally routed and provided by the MRI machine manufacturer to an interface point on the bottom of the trailer. In hooking them up, we've followed the cables inside, and found them not to be in metalic conduit.
The last MRI trailer we did, we ran fiber out to the pedestal due to the distance the unit was from the hospital building. In the pedestal we have a fiber optic transceiver and it is Cat6 to the trailer for the data. We've been very pleased with the marinco marine telephone jacks and plugs for phone, and the Seimons industrial ethernet connectors for data. It rains so much here, this stuff is pulled in and out of service twice or three times a week with no water trouble.
If it were an issue, I would still think the most immunity would be provided with a grounded metallic conduit. However, your best resource may be the manufacturer of the equipment. When we wire these units up for power, the manufacturer provides complete details for the entire room, and generally a tech is available with the equipment to answer questions.
Good Luck!
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
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Daron ,thanks for the response,I am aware that the switches actually are supposed to balance the signals through balancing a magnetic field ,but I was afraid that the spare pairs in cat5 could cause induction ,and create some possibilities for strange behavior, because even though it is a magnetic field itself it being controlled through the switches,I was afraid the introduction of an uncontrolled field might make it perform strangely.Are there different kinds of magnetic fields?This installation itself was done in such a manner it lends itself to all kinds of possible interference, there network cabling needs to be replaced and re-installed anyway because even though they are limited in compliance,it should have been installed with as much compliance in mind as possible.As I stated earlier on,It was such a limited pathway it appears whoever installed the majority of the cabling did even try to comply or wasn't aware how to comply.We have urged them to let us test and mark the cables ,just to see how bad it really is.They are allways having strange behavior on their network. Thanks again for your insights.
Servamatic
IS-IT--Management
In hooking them up, we've followed the cables inside, and found them not to be in metallic conduit. " from Daronwilsonson post.
The Cat5 wire twist has excellent interference canceling ability due to the IEEE specification/concern for noise cancellation. This is the reason for Daron's findings of no shielding in the MIR unit.
For my experience with EMI radiation
The one problem which might induce interference in the Cat 5 wire is the quality of termination. In many installation, I have found the wire twist is not maintained properly at termination blocks/plates. Often I see more than an 1/2" inch of untwisted wire at termination points ( usually > 1". 1/2" is the recommended), which basically voids the cat5 spec, producing small antennae to allow extraneous signals into the system. With the high EMF produced by an MIR careful tight termination will be critical.
recommended practices
Extra time, check out info about EMF bombs (the US has in it's arsenal)..
The Cat5 wire twist has excellent interference canceling ability due to the IEEE specification/concern for noise cancellation. This is the reason for Daron's findings of no shielding in the MIR unit.
For my experience with EMI radiation
The one problem which might induce interference in the Cat 5 wire is the quality of termination. In many installation, I have found the wire twist is not maintained properly at termination blocks/plates. Often I see more than an 1/2" inch of untwisted wire at termination points ( usually > 1". 1/2" is the recommended), which basically voids the cat5 spec, producing small antennae to allow extraneous signals into the system. With the high EMF produced by an MIR careful tight termination will be critical.
recommended practices
Extra time, check out info about EMF bombs (the US has in it's arsenal)..
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fiberman40
Technical User
Just my two cents, but I have worked in a few MRI units and the conduits generally were of the non-ferrous type, aluminium or one of the intermediate type conduits. I was told one of the things about the room for an MRI it has to be free of RF because the image actually is created by the reflection of radio frequency from the cells. Generally the room is sheilded by a copper type mesh and grounded as to create an RF free area. I also would think STP would be the required cable for crossing through this room.
I am told people with dark skin pigment can actually receive what feels like sunburn if exposed to the RF energy too long.
I WILL FISH FOR FOOD
I am told people with dark skin pigment can actually receive what feels like sunburn if exposed to the RF energy too long.
I WILL FISH FOR FOOD
Servamatic
IS-IT--Management
I for one would like a little clarification...
Are you talking about Shielded Twisted Pair (STP) which generally runs Token Ring, or Screened Twisted Pair (ScTP).
There is a huge difference between the two, and normally we would run ScTP, not STP, as STP will be dropped from the standards on the next revision most likely.
Richard S. Anderson, RCDD
Are you talking about Shielded Twisted Pair (STP) which generally runs Token Ring, or Screened Twisted Pair (ScTP).
There is a huge difference between the two, and normally we would run ScTP, not STP, as STP will be dropped from the standards on the next revision most likely.
Richard S. Anderson, RCDD
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