Live Q&A responses

MRI Safety and customer satisfaction - the architects' & planners' role

Live Q&A responses

MRI Safety and customer satisfaction - the architects' & planners' role

Webinar Questions and Answers

Our recent webinar with Tobias Gilk included a Live Q&A session. Below you will find details of all the MRI safety questions asked as well as responses from Tobias.

Suggestion to Tobias: mention the MR Safety Facebook group (that you moderate)

I think you just did! :-) For anyone interested, the facebook group (dedicated to answering questions about MRI safety) can be found at https://www.facebook.com/groups/MRIsafety/

Thoughts on scan room door locks? Electronic touch pads vs dead bolt vs proximity badge RFID technology ?

I agree 100% with the ACR Guidance Document that combination locks (whether mechanical or electronic) should not be used to secure the MR Zones. Access controls should not be ‘sharable’ (like combinations are). There should be a physical key… a conventional metal key, or an individual RFID proximity card, or a biometric key.

Love the Russian-doll metaphor to describe the Zone system! I’ll be stealing that, for my Safety training slides (for my Radiology etc colleagues here).

I’m glad you like it! We often get so wrapped up in the technicalities of ‘what constitutes a Zone II or Zone III’ that it becomes easy to lose sight over the bigger organizing principle.

I have a Philips Amition. No quench pipe

Indeed, there are magnets (including these new Philips magnets) that either don’t have any on-board cryogens, or such a small amount that they don’t need quench pipes. Today, however, there are far more magnets being installed that *do* require quench pipes. For the forseeable future, we’re going to have to continue wrestling with the design issues assocated with them.

Are both pressure relief ducts and emergency exhaust required or typical for new MRI ventilation design standards – in the case of a quench event?

Separate pressure relief has been an MRI suite design criteria from the 2014 FGI Guidelines, onward. While not every state has adopted the more contemporary FGI Guidelines, but I recommend that designers follow these more current / comprehensive standards, even when local / state minimum standards are less than the FGI.

One of the FMD manufacturers touts as an advantage their ability to install their FMDS in Zone IV. I believe that I heard you say that this is NOT ideal and does not comply with ACR guidelines. Can you please elaborate?

The ACR Guidance Document does specifically identify the purpose of ferromagnetic detection systems as “the use of ferromagnetic detection systems is recommended as an adjunct to thorough and conscientious screening of persons and devices approaching Zone IV.” I think this pretty clearly indicates that the intention is to screen *before* the doorway. Even if that isn’t the explicit intention of the ACR Guidance Document, I personally think that detection inside the magnet room is ‘too little, too late.’ I have always encouraged sites – in the strongest possible terms – to place their ferromagnetic detection system products prior to the door into the MRI scanner room.

Do you have any references for MEP design standards (HVAC, Electrical or Fire Protection & Plumbing)?

The VA has good references for MEP services. I’m currently working on an update to the Imaging Services Design Guide, which I hope will be out in early 2020. Until then, you might want to check out the MRI specific guidance in the VA’s Electrical Design Manual (https://www.cfm.va.gov/til/dManual/dmElec.pdf) and in the VA’s HVAC Design Manual (https://www.cfm.va.gov/til/dManual/dmHVAC.pdf). Additionally, I strongly recommend following the recommended design guidance in the MRI manufacturers’ siting manuals (not just the project-specific site drawings).

Do you recommend Zone 4 doors swing into the room? Isn’t that a problem during a quench?

All other things being equal, yes, I do recommend swinging the magnet room door *into* the MRI scanner room. This makes siting FMDs easier and can help improve the functional performance of the FMD. Since outswinging doors don’t provide the quench-entrapment safety that they once did (back when they were mostly friction-fit and not latching), rooms should be outfitted with overpressure relief anyway.

those pictures shown projectile damage. Did they happened while mri was operating?

Unlike almost every other imaging modality where the energy is only present during imaging (e.g., X-rays), the main magnetic field of an MRI is there 24/7 (and so is the risk of things getting drawn to the scanner). I don’t know the details of a couple of those images, so I can’t say if the patient was inside the MRI scanner, but I would expect that all three of those pictures of things stuck to the MRI scanner were from when the patient was being brought into the room for the first time.

What will the screener patient system add to the ferromagnetic detection system. How are they different?

Ferromagnetic detection systems’ sensitivity is – in part – a function of how close the detector is to the subject. If the detectors on either side of a doorway are 5 feet apart, then there will always be an area of the person being screened (walking between them) that is no closer than 2′-6″ from the detector. Contrast that with walking a patient right up next to the detector, and spinning them around. You’re likely to get a screen that’s 5x closer than the doorway system. It’s also true to say that screening FMDs are generally set to much higher detection sensitivity levels than the doorway systems. I’m aware that there are journal papers showing Metrasens’ screener system is capable of detecting implants containing ferrous material, e.g. pacemakers, which is far beyond the ability of doorway FMDs. In practical terms this means you have a greater likelihood of finding smaller ferromagnetic objects with a screener system than with a doorway system. Operationally, it’s also preferable to do this screening verification where you’re having the patient change and store their belongings.

Do you recommend doing a floor design that outlines the pertinent gauss lines for equipment?

Yes. While I generally think that makring the 5-gauss line is pointless, I strongly suggest marking the flooring with the threshold values for usage of MR Conditional equipment such as anesthesia machines.

Do you have any information regarding DNV requirements for MRI suite design and safety?

I don’t, but I wish I did. As near as I can tell, DNV doesn’t have objective standards for MRI physical safety. For sites that have DNV accreditation, I would very strongly encourage that they use other more explicit standards for MRI physical safety, including the 2018 FGI Guidelines for new facilities, and the ACR Guidance Document for operational standards.

Have you ever been involved with a cardiac MR/ Cath suite that involves moving the pt. between the cath lab and the MR suite involving doors that open between the two rooms? If so, any recommendations?

All forms of interventional / intraoperative MR suites get really complicated, really quickly. We’re trying to overlap Four Zone access restrictions with infection control and emergency access needs, and they often come into conflict. I wish there was a good guidance document just for interventional / intraoperative MR systems, but I haven’t seen one yet. In the meantime, all I can suggest is having someone on your planning teams who can help identify these conflicts and facilitate the user-group discussions that can identify resolutions to the conflicts. Sometimes those solutions are ‘bricks and mortar,’ and sometimes they’re operational processes. But please don’t count on the users resolving the issues after the project is built… too often I’ve seen constructed projects that would have been markedly improved by addressing these issues in the design stages.

GE requires door to open out in Canada.

If that’s the case, then here GE is just plain wrong. Not wrong in the sense that swinging the door out is wrong… but the reason that they likely think that they’re requiring the out-swinging door isn’t really going to work like they think it will. The more recent editions of the FGI Guidelines specifically say (a) provide dedicated overpressure relief and, (b) swing the door whichever way you wish. I suggest swinging it into the magnet room. If you’re working on a project where GE is pounding their fists about the direction of the door swing, loop me into that conversation and I’ll do what I can to help you.

Would it not be as effective to install the FMD between zone 2 and zone 3 since zone 3 is for completely screen patients?

That depends. If a site keeps ferromagnetic materials in Zone III, then you probably want the doorway detector on the door into the magnet room. If you have a ‘staff entrance’ to Zone III which bypasses the area and resources for Zone II screening, then you probably want to have the doorway detector at the door into the magnet room. The optimum location(s) for FMDs depend on facility layout, staff / patient flow dynamics, and the equipment you have in the different areas. I’ve designed FMD siting for sites at lots of different locations. Sometimes that has been somewhere freestanding in the middle of Zone III, or at the door from Zone II into Zone III, but the solution that has been the best option for the majority of sites I’ve worked with has been at the door into Zone IV.

The 2018 FGI requires the 25′ perimeter surrounding the quench vents be identified. Have you considered various approaches to provided a physical identified that takes into account the potential of snow buildup on rooftops?

Many of the manufacturers have a minimum vertical clearance above the roof of 3′ *above* the height of any snow drifts. If we’re talking about a hospital in Miami, then that means 3′ above the roof. If we’re talking about a hospital in Vail, that might mean that the quench discharge point needs to be 9′ above the roof (3′ above a potential 6′ snow drift). The horizontal clearance shouldn’t change with the potential for snow accumulation, but the vertical clearance must.

is it debatable as to scanner room door opening in or out. Ge requirement in Canada is door opening out

See my earlier answer to a very similar question. In short, GE in Canada is – in my opinion – enforcing an outdated standard that has been made obsolete.

Do manufacturers have the bloom field lines to aid us in planning the size of the scanner room?

I understand that most (all?) contemporary actively-shielded MR systems now use continuation of the main magnetic field coils as their active shielding coils. When those were separate systems, it was possible for the active shielding coil to fail, essentially ‘releasing the girdle’ and letting the main magnetic field expand. Now that these are a single system, an expansion of the magnetic field to a ‘bloom’ condition isn’t possible. If you have any question about an MRI system you have or are siting, please check with your MRI equipment manufacturer to get the specifications particular to that magnet.

Do you have any dedicated Open MRI low field webinar or safety articles?

That’s a good question. I’m surprised that I can’t think of any right now. Of course there’s lots of attention to newer, stronger MRI systems, but low-field and vertical-field systems do have some different siting and physical safety considerations.

How does one secure the “trap Door”

If you’re referring to an overpressure-release hatch, it should remain free moving (unsecured). The way to keep it closed then is to have it open into a room that is locked or access controlled. My personal preference is for ducted overpressure relief (ducted to the outside or a large unoccupied space, like an interstitial floor) so that you don’t have to accommodate the ‘doggie door’ type hatches.

LoL in the room for FMD….that is kinda funny!

I once worked with a hospital that had an amazingly-cramped control room. There was just no way to put the FMD that they wanted in Zone III… not even rearraning functions in the control room. They asked if they could / should put the FMD inside the doorway. I told them that, in my opinion, the FMD would be so compromised in that location that they’d be better supporting other safety resources. I am a huge safety advocate, and a strong proponent of FMDs, but honestly I think that putting them inside the MRI scanner room so reduces the function of these devices that I can’t in good conscience recommend them there.

The only drawback of the ferrous detector at door is a “manufacturer’s” table contains ferrous materials and sets ours off constantly :( Alarm fatigue does set in with this and because of this.

Yes, every MRI system manufacturers’ un-dockable table that I’m aware of includes ferromagnetic materials, and will alarm a FMD. This does call for an alternative screening strategy for patients brought into the room on the OEMs’ tables. There are, however, wholly nonferromagnetic transport tables that can be used to move patients into and out of MRI rooms that will not set off FMDs. That does require that the staff do a slide-transfer from the transport table onto the table for the MRI scanner. Also bear in mind that for every patient entry on such a docking table, there are likely to be many more involving technologiists and other team members entering the room at times other than patient entry. An FMD located at the Zoine IV doorway will therefore still enhance safety for the majority of entries into the magnet room. It can be argued that for the patient entry itself, it’s relatively straightforward to implement a rigorous visual inspection for projectile risk items, the higher risk probability is the non-procedurised entries of anesthesiologists, etc; who can still be effectively screened by an FMD.

What kind of positive pressure release do you recommend for in-swing doors? I’ve heard that a standard (non-rolling) latch on an out-swing door can get stuck in the door jamb if there is lots of He gas in the room so a pressure release would also be required in this case?

I prefer a duct that runs from the magnet room straight to the outside (typically about 4 square feet of free area). This will allow any positive pressure within the room to be discharged outdoors, and will let you operate the door to / from the MRI scanner room without pressurization.

Is there a good resource for ferrous detector workflow/policy? For example, if a patient can’t not clear the screener(all green) and image/op reports have been checked and no implant listed. Would you turn away the patient?

This is a great question, but is bouncing back and forth between strictly operational and clinical safety. In general, I recommend trying to get to the bottom of *any* alarm condition. But if the patient has an implant or foreign body that is a source of alert / alarm, then it’s a clinical question about how to complete the screen and clear the patient to go on. I would strongly recommend having a trained and designated MR Medical Director (MRMD) and MR Safety Officer (MRSO) who have the knowledge and competency to help with these sorts of case-by-case clinical clearance situations.

Free Guide to MRI Safety & Ferromagnetic Detection Regulations

With multiple professional and accrediting bodies involved, it can be difficult to keep track of what the various published safety recommendations and guidelines in the US say. Metrasens is pleased to assist by providing this summary of the present status as it relates to the growing adoption of ferromagnetic detection systems (FMDS) for the prevention of MRI projectile incidents.

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