MRI Sound Isolation

May 2, 2011 by Benjamin Davenny

Benjamin Davenny

Magnetic Resonance Imaging (MRI) systems are capable of generating high sound levels in MRI

rooms, which can be transmitted to adjacent spaces. The most prevalent systems contain 1.5 and 3.0

Tesla (T) magnets, which have measured maximum sound levels approximately between 90 and 100

dBA (A-weighted decibels). 7T magnets are beginning to appear in clinical use, but measured sound

data for these machines is limited.

The frequency content of the sound generated by MRI systems typically peaks in the mid-frequencies,

between 500 Hz and 2,000 Hz. Mid-frequency sounds are easier to attenuate with building

constructions than low frequency sounds from building mechanical systems. However, the sound

levels and tonal character of MRI sounds require significant building constructions.

Sound isolation measures should be integrated with the radio frequency (RF) and magnetic shielding

enclosures to reduce sound transmission to adjacent areas. Concern for adjacent spaces, that is

rooms that are not directly connected to the function of the MRI, include spaces vertically adjacent

and horizontally adjacent to the MRI suite. Noise transmission to spaces below the MRI can be

reduced with a resiliently suspended gypsum board ceiling above the finished ceiling. Spaces above

the MRI can be protected from MRI noise by wrapping the gypsum board of the enclosure walls

above the MRI room finished ceiling, creating a gypsum board box inside the RF shielding.

Horizontally adjacent spaces of the MRI suite can be protected by constructing a separate wall

outside of the shielding wall with an airspace between the two walls. Spaces within the MRI suite

have greater tolerance for MRI sounds and have elements in the building construction that limit the

performance of the walls, such as doors, windows, and waveguides. MRI systems can also transmit

sound via structureborne noise transmission. Vibration of the magnet is transmitted to the magnet

feet and then to the floor, and is reradiated as airborne sound in spaces below as well as horizontally

adjacent spaces.

Structureborne noise transmission is much easier to reduce when the magnets are located on slab on

grade, where the supporting structure is more stiff and massive than on framed floors. All MRI

magnets should be mounted on the manufacturers recommended vibration isolation system. Some

cases of magnets installed on framed slabs require a two-stage isolation system involving the

manufacturers isolation pads, intermediate stainless steel plates, and a second layer of pads below

the steel.

Benjamin Davenny is Senior Consultant, LEED AP BD+C, EDAC, with Acentech. For more information,

visit www.acentech.com. Davenny can be reached at bdavenny@acentech.com.

4 Things You Need to Know About Your MRI Shielding Contractor

Administrators, Architects, Imaging Directors, MRI Noise Solutions Comments Off on 4 Things You

Need to Know About Your MRI Shielding Contractor

The architects role in planning for magnetic resonance imaging (MRI) suites is ever expanding. It is

well known that MRI suites are ground zero for significant and growing numbers of preventable

adverse events. MRI suites are also really, really loud both inside the room and in adjoining spaces.

MRI suite safety can be improved with enhancements to operational elements like: training,

screening, and patient-management protocols (including secured entry access methods).

Conscientious and thorough prospective site planning can improve safety and create an environment

that benefits patients, healthcare workers, and visitors.

The architects finishing touches and aesthetics combine to make the entire design a success

overlaid, of course, on a safe and functional backbone. In addition to patient flow and lighting,

acoustical considerations are critical.

MRI shielding consultants offer educated advice customized to your situation. Experienced shielding

consultants design solutions to dampen noise inside the scan room while reducing sound levels

throughout the suite. They also can offer additional techniques to maintain isolation from the

building structure to eliminate critical structure-borne acoustic components.

In addition, knowledgeable MRI shield vendors understand how to customize solutions by

incorporating a variety of material layers and insulation within the shield itself. Minimizing noise levels

is a particular design priority in Childrens Hospitals and Cancer Centers where there is a unique

patient susceptibility to noise.

Choosing the best MRI shielding contractor is critical to the success of the project. So, here are five

things to look for in an MRI shielding partner:

1. Expertise in applying the physics of radio frequency (RF) shielding, magnetic shielding, and

acoustic shielding while maintaining focus on safety considerations.

2. Experience in radio frequency (RF) and magnetic shielding in MRI systems.

3. Improves effectiveness and efficiency of the team with proven processes to shares expertise

with all cross-functional partners in the project.

4. Finally, make sure to check what kind of warranties the shielding contractor offers.

Meaningful warranties protect architects even after the initial construction is complete.

5. At IMEDCO, weve got more than just thousands of installations under our belt. Our focus on

the human experience is what sets us apart.

From planning to design to construction, we understand the importance of the ultimate result:

enhanced patient care. We dont simply rely on structural designs. We know how to make acoustic

solutions and dimensional space more cost-effective.

Our MRI shielding solutions have been independently measured and verified for calculated acoustic

level performance. This allows us to predict results and offer tools that architects use to make MRI

shielding implementation even more effective. IMEDCOs comprehensive MRI shield solutions benefit

all, and can further increase the architects value to clients.

IMEDCO is a division of the largest dedicated MRI shielding company in the world. Our patented best-

in-breed designs (in RF and acoustic shielding materials and methods) provide preeminent noise

reduction. We design interior framing/furring, acoustic batting within all RF panels, and door and

window high-performance acoustic components critical elements for successful clinical or research

MRI applications. IMEDCOs designs incorporate the latest Ferrous Metal Detection

systems (FMDs) and special provisions for IV entry, neatly into the door designs.

We back all this up with the best warranties in the industry. Call one of our consultants today.

GE Silent Scan turns down the volume on MRI scanners

By Brian Dodson - January 6, 2013 1 Picture

GE's new Silent Scan technology is designed to significantly decrease noise during MRI scans

GE Healthcare has introduced a new data acquisition technology designed to improve patient comfort

by largely eliminating the horrible noise generated during an MRI scan. Conventional MRI scanners

can generate noise levels in excess of 110 dBA (creating a din that sounds like a cross between a

vehicle's reverse warning horn and a Star Trek phaser) but GE says its new Silent Scan MRI

technology can reduce this to just above background noise levels in the exam room.

The noise that MRI scanners produce is related to changes in the magnetic field that allow the slice

by slice body scan to be carried out. In recent years, industry efforts to speed up the scanning

process have also resulted in louder and louder scans. The designers have attempted to dampen

these noises with mufflers and baffles, achieving only limited success.

Silent Scan is achieved through two new developments. First, acoustic noise is essentially eliminated

by using a new 3D scanning and reconstruction technique called Silenz. When the Silenz protocol is

used in combination with GE's new high-fidelity MRI gradient and RF system electronics, the MRI

scanning noise is largely eliminated at its source.

At the 2012 meeting of the Radiological Society of North America, an MRI system compatible with the

Silent Scan technology was linked into a soundproof room. When the MRI system used conventional

scanning methods, a staccato, stuttering racket with noise peaks up to 110 dBA was heard. However,

when Silent Scan was switched on, the noise level dropped to 76 dBA, just above the background

noise of the MRI electronics. This is accomplished without substantial trade-offs in scanning time or

image quality, according to Richard Hausmann, president and CEO, GE Healthcare MR. The

comparison is shown in this video.

Silent Scan technology has not yet obtained 510k Premarketing Notification clearance from the FDA,

so it's not yet available for sale. GE is presumably hoping for a decision that Silent Scan is

"substantially equivalent" to existing MRI scanners, a result that would greatly simplify the new

technology's entry into the diagnostic market.

I am a big fan of this! With any luck, this could make MRI scans more commonplace!

Seriously, why do many doctors just assign CT scans and never even mention MRI when it's just

BETTER for rendering flesh? They often don't even offer the patient a choice!

Joel Detrow

I would refer to the noise as more like a cross between a stalled electric motor and a jackhammer,

but hey, de gustibus. Still, it is a lot of noise (it would probably spank some Bose headphones) and

can be a bit unnerving for nervous types and small children. A welcome improvement.

Bruce H. Anderson

Now if they could just make the donut hole bigger - they have to knock me out to get me into one of

them. . . {{shiver}}

socalboomer

@ Joel Detrow. You are correct, MRI is superior in the imaging of soft tissues. However it is not as

good at imaging dense anataomy such as bones. It also takes an average of greater than 20 Minutes

for any given scan. This precludes it from emergency medicine where a Doctor needs to know about

any life threatening injuries as soon as possible. Because of a CT's fast imaging acquisition they can

also be used for procedures such as where the patient has a degenerative bone condition and they a

need treatments such as injecting plastic into the spine to reinforce the vertibrae. The CT can provide

multiple, rapid acquisitions so the surgeon knows they are putting the plastic in the right place. MRI

scanners also cost substantially more to buy and run. This means an MRI scan is dearer than a CT.

Modern high-resolution MRIs need liquid Helium to super-cool the coil which forms the high tesla

magnet. Helium is not only expensive, but known reserves are being rapidly depleted. This makes the

future or MRI in it's current form uncertain. Because MRIs are a super-magnet, they cannot be used

for a wide variety of patients. Those that have metallic implants and pace-makers among others.

There are far less MRI scanners when compared to CTs so it would simply be impossible to have all

routine CT scans changed to MRI. So as you can see, it's not as simple as just offering a patient the

choice or CT or MRI. A doctor has a lot to consider when choosing what type of imaging modality to

select.

Australian

@ socal boomer - I assume you say that because you're claustrophobic...well, you do know you could

always go to a place with an upright MRI...dont you? Those ones you can stand/sit/lay, and you won't

feel as trapped.

Derek Howe

Toshiba has had noise reduction for about 15 years that's hardware based and on for every sequence

without compromise to image quality. The techniques the GE and Seimens utilize are software based,

and dependent upon the sequence. It remains to be show that there will be no impact on image

quality. Also, they can't use it on DWI (the loudest sequence. Side note: get medicated and have an

MRI on a superconducting magnet. The "stand up" magnets are unable to show many things, which

is why we have seen a drastic change in the industry, and most open magnets will be gone in the

near future.

There are more and more "zero boil off" magnets, thus decreasing the helium usage. Also keep in

mind, a routine brain only a few years ago took 30 to 45 mins of scan time... Now it's down to 9 to

12 mins. MRI and its potential is limitless. It's important to keep in mind with the new dose tracking

guidelines for CT, MRI is the safer alternative. A CT of the chest is like getting 300 chest X-rays, a lot

of radiation. Most metal implant are compatible at 1.5T (but should still be researched for safety),

and there are MR comparable pace makers now... It's the future of imaging. (There's been a helium

shortage for the past 10 years, but in those years, more and more MR exams have been done).

Project Design :: MRI Room

Goal: To minimize the impact of noise generated by MRI equipment to

surrounding areas and within the treatment rooms.

Related Codes & Standards

o Sound Transmission Class (STC)

Tips/Considerations

o MRI equipment can be very noisy. Consider the patient, who is already in a stressful

situation; the technician, who could be exposed to this noise level throughout the

entire day; and the adjacent spaces, which could be impacted by the MRI noise.

o To create a more comfortable environment for the patient and technician, and to help

reduce the possible noise transmission to adjacent spaces, the ceiling and the

majority of the walls should be treated with an absorptive material.

o To help protect the technicians, the observation window and door must have an

appropriate STC rating. Remember, it's not just the rating of the window and/or door

that is important; you must also consider how well it is sealed within the assembly.

o To reduce noise impact from the MRI room to adjacent spaces, the isolation quality

of the walls and floor-ceiling assemblies are vital. The wall and floor-ceiling

assemblies must have substantially upgraded isolation, as a typical (or even a

typically upgraded) wall or assembly might not be effective.

o The nature of an MRI requires that special care be taken in product selection and

method of attachment in order to avoid interfering with the magnetic field.

Related Projects

Preparing for an MRI

MRI Sound Levels - MRI Loudness

After speaking with MRI technicians, we've learned some interesting things about MRI machines.

Loudness, Ear protection, Earplugs

An MRI machine is loud. I've observed the procedure inside the MRI room. A friend was given

an MRI for his upper neck region. I sat in the MRI room with him, for moral support. The

procedure lasted several minutes.

Because the MRI machine is loud, MRI patients are often offered protective earplugs by the

MRI technician. The earplugs can block out some of the noise emitted by the MRI machine.

We suggest using at least an 29dB NRR of protection. This means a Noise Reduction

Rating (NRR) of 29 decibels, designed to block out 29 db (decibels) of sound. I regularly use

Mack's NRR 32dB soft foam earplugs or HEAROS Xtreme NRR 33dB soft foam earplugs. I only

use NRR 32dB and higher.

The MRI technician should offer soft foam rubber earplugs to the patient. The MRI technician

should also offer earplugs to any visitors in the MRI machine room.

How many decibels is an MRI?

We suggest you ask Doctor Frank Shellock. You can find his MRI website here. Also, you can

read about MRI safety guidelines at the IMRSER website.

MRI Acoustic Information is here, at Dr. Shellock's MRISafety website.

How can I be prepared? Will my MRI be safe?

No matter what part of your body is being imaged, you should be screened by the MRI

technician before you get the MRI. Whether it's your finger, your leg, or your brain, you

should be screened by the MRI center.

They screen you to determine whether it is safe to conduct the MRI procedure.

What about the Magnet on the MRI? What does it do?

As stated by the Mayo Clinic, there are no known harmful magnetic effects for most persons.

As stated on the Mayo Clinic website: "For most individuals, there are no known harmful

effects from exposure to the magnetic field or radio waves used in making MRI images."

What is "screening"? Why do they screen me?

Screening means the MRI technician should ask you a series of questions and/or provide you

a written questionnaire. (This is also true for visitors who will be in the room during the MRI

imaging.) The technician does this to determine whether it is safe to conduct the MRI

procedure. The technician will ask you such questions as:

Have you had any implants or surgeries in the past?

Do you have any metal objects in the part of your body that is going to be imaged?

Have you had a shunt (a tube) implanted in your brain?

If you've had a shunt, was it adjustable (with different pressure settings)?

Do you have Hydrocephalus?

What kinds of questions do they ask in a screening?

For examples of screening, see here (screening form in PDF format) and here.

Where can I find more information on MRIs ?

Please see the links below.

How loud is an MRI machine?

We suggest you ask Doctor Frank Shellock. You can find his MRI website here. Also, you can

read about MRI safety guidelines at the IMRSER website.

MRI Acoustic Information is here, at Dr. Shellock's MRISafety website.

MRI Websites

MRI Safety Site - by Dr. Frank G. Shellock, Ph.D.

MRIsafety.com

Institute For Magnetic Resonance Safety, Education, And Research

www.IMRSER.org

MRI testing services for implants and devices:

www.MagneticResonanceSafetyTesting.com

How loud is an MRI machine?

We suggest you ask Doctor Frank Shellock. You can find his MRI website here. Also, you can

read about MRI safety guidelines at the IMRSER website.

MRI Acoustic Information is here, at Dr. Shellock's MRISafety website.

--

child at an MRI machine

--

Permalink: MRI Preparation, MRI Sound Levels

Tags: diagnosis, fmri, medical machines, MRI, noise levels, radiology, NRR, MRISafety site, Dr. Frank

Shellock, hydrocephalus, shunt, 3D, images, imaging, acoustical noise, how loud is an MRI

Permalink: http://www.thedailydecibel.com/2010/07/mri-preparation-mri-sound-levels.html

Plant Room Noise Assessments

by Carl Strautins

in Noise Assessment

6 Jul 2015 | 0 Comments

Plant rooms may be noisy - has your building plant room been

tested

Plant Room Noise Assessments

Safe Environments were recently engaged to provide noise assessments of plant rooms in commercial

buildings within Sydney CBD. The purpose of the noise assessments was to determine whether the

noise levels within the rooms may pose a risk of industrial deafness or noise induced hearing loss.

Sources of Noise within Plant Rooms

The equipment within plant rooms in buildings can include a number of noisy machines and

equipment. The majority of noise in plant rooms generally come from the air conditioning equipment.

The noise of chillers turning on and off can be quite expectant with no time to prepare. The noise

associated with air conditioning within the plant rooms is through fans supplying air throughout the

building. Fan rooms can be a quite noisy place to be.

Cooling towers with the noise of water cascading through, as well as hydraulic pumps to move the

water around can increase the noise levels within the plant rooms. Boilers can also create significant

noise levels as well.

Lift control rooms can have a constant clicking of the switches turning on and off. The sound of the

lift motors, pulleys and breaks can contribute to the overall noise exposure. In many instances, the

lift control room needs to be cooled to ensure that the plant does not overheat. These are generally

through fans the use of split air conditioning systems that feed directly to the lift room.

Plant Room Noise Testing

The noise assessment is first conducted through noise levels measured throughout the room. Due to

the number of plant and equipment within the building, each piece of noise generating equipment

should generally be measured. Many items may not be operating and a long period of testing may be

required.

Noise Assessment Report

The report should outline the sound levels within each of the plant rooms along with the associated

noise generating plant and equipment. The report should also outline whether the day was

representative. It may be preferable to undertake testing both in summer and winter as there will be

different operating times for the equipment.

Reporting of the Plant Room Noise Levels

The noise within the plant rooms should ideally be below 80 dB(A) however it is recommended that if

the assessment identifies that the noise levels are greater than 85 dB(A) then signage should be

provided at the entrance to the plant room.

Before entering the plant room with noise levels of 85 dB(A) it is recommended that Personal Hearing

Protection (PHP) be provided. The type of PHP that is provided will be dependent on the noise levels

as well as the activity that is likely to be conducted.

For more information on noise assessments and surveys, please contact Safe Environments, based in

Sydney and Melbourne

MRI Noise and Vibration Isolation

We recently heard about an MRI Unit installed on the second floor of the medical building that was

being heard in surrounding spaces on the first floor. The unit was mounted on steel springs and that

didn't work. Spring mounting is not recommended due to concerns about movement of the unit due

to the strong magnetic impulse. In this case we typically suggest mounting the MRI on resilient pads

and installing a floating floor system around the unit to cover the exposed floor area in the room.

That along with a resiliently suspended ceiling in spaces below the MRI Room will reduce the noise. It

all depends on location, location, location.

Be the first to comment!

See previous comments

Jack B Evans, PE

Carel,

I can find a copy of that paper if you can't. You presented it at Acoustics'08, Paris in

the session Marc Asselineau and I chaired. Very valuable information. I have used or

referenced your findings in several MRI installation designs in new and renovation

facilities in the US.

February 9, 2012

Chris Papadimos

Are any of you saying that structureborne noise due to the rigid attachment of the

quench pipe to the structure is not an issue for occupied spaces above and do you

have any specifics on solutions? We have MRI's these days on elevated floors and all

types of critical adjacancies to deal with so any comments I am sure they would be

much appreciated.

February 9, 2012

Jack B Evans, PE

Chris,

The structure borne transmission path may indeed be a problem, but the quench

pipe issue introduced by Carel is an airborne transmission from magnet room via the

pipe. If the pipe terminates near a window or near an occupied space, one can hear

the magnet scan noise clearly. To illustrate, if you have seen the voice pipes from

bridge to engine room in 19th, 20th century ships, image the engine room as MRI

magnet room, and termination of pipe in bridge as distracting noise source near

executive conference room or the conference room window.

February 9, 2012

Carel Ostendorf

My paper is simply to find on the internet:

http://webistem.com/acoustics2008/acoustics2008/cd1/data/articles/002987.pdf

February 10, 2012

Kevin Packer

Thanks Carel! Very interesting. In addition to noise radiated from the outlet of the

quench pipe and structure-borne noise via rigid connections to the pipe, noise

breaking out of the walls of the pipe could also be a concern (depending on the pipe

construction and where it is routed). We were involved with a project where the

client was proposing to install an MRI clinic at ground level directly below lawyers'

offices in a lightweight steel frame commercial building. The quench pipe was to be

located in a shaft adjacent to an office in the lawyers' space.

We assisted the architect with design of acoustical isolation for the magnet room,

quench pipe, and various other potential noise issues, but thankfully in the end, they

found a more favourable location for the clinic somewhere else (presumably not

adjacent to lawyers).

February 10, 2012

Brad Pridham

I just came across this discussion. A very important issue that I also face on many

facilities. A particular concern in medical research where we are now seeing 7T full-

body investigational devices going in next to rail. Here is an interesting paper that

describes a successful installation on traditional passive springs:

http://www.sandv.com/downloads/0612tret.pdf

It would be interesting to know how well this one is performing, particularly with

respect to the low damping and settlement time on steel springs once disturbed by

someone walking on the floor. On this installation there was a 30 second 'ring-down'

time when disturbed. Could the magnet induced vibrations lead to unacceptable

motion of the system? I presume the amount of mass present would prevent

significant motion, but how significant are the forces from the magnet?

February 25, 2014

Angelo Campanella

The only persons that can comment realistically on the performance of this MRI are

the doctors using it, and having studied its day to day images, and are willing to

comment on the image quality that it has been producing. If the image resolution is

sub-par (poorer than other MRIs that they have used). Some sort of blurr measure

must be defined, typically mm or microns pk-pk blurr.

February 25, 2014

Carel Ostendorf

@Brad, thanks for sharing this paper.

According to the last paragraph of the summary, the MRI performs well.

February 26, 2014

Chris Papadimos

I like Angelo's idea about direct inquiry with doctors. Any volunteers and also

predictions how it is working? I will check with Mason listed as co-author and circle

back.

February 26, 2014

Angelo Campanella

We need a criterion-method to referee this matter. MRI installations are big,

expensive and subtle in their operation. Isolation methods and hardware are exotic

and expensive. We face two influences that have to be refereed successfully; room

sound that may be created and vibrations that may undermine final performance

(image blurring). When someone says "It works OK", I can't tell whether noise and

vibration were tamed adequately, or that it merely operates and produces some

useful imagery. What will satisfy us will be a room ambient sound level spectrum,

while that MRI is put through some paces, and a still image sample (of a 2X4?) to

show absence of blurring of 0.1 mm (WAG) or more when a fast train goes by.....

February 26, 2014

Vibrations of the gradient coil support structure create sound waves. These are caused by the

interactions of the magnetic field created by pulses of the current through the gradient coil with the

main magnetic field in a manner similar to a loudspeaker coil. The sounds made by the scanner vary

in volume and tone with the type of procedure being performed.

Sound pressure is reported on a logarithmic scale called sound-pressure level, expressed in decibel

(dB) referenced to the weakest audible 1 000 Hz sound pressure of 210-5 pascal (20 micropascal).

Sound level meters contain filters that simulate the ears frequency response. The most commonly

used filter provides what is called 'A' weighting, with the letter 'A' appended to the dB units, i.e. dBA.

MRI system noise levels increase with field strength. Disposable earplugs and/or headphones for the

patient are recommended in high-field systems. Noise-canceling systems and special earphones are

available, and active acoustic control systems were developed, e.g. softtone, pianissimo. A sequence

with low noise gradient pulses is also called 'whisper sequence'.

See also Phon and Decibel.

I have had various MRIs over the years. Most of them have involved the dreaded tunnel. It has never

really bothered me until today. Maybe it was the one and one-half hour wait before the MRI. Guess

that's why they call it a waiting room. Anyway, the sound today was absolutely deafening. Are you

telling me that they can build a Magnetic Resonance Imaging System and they can't build a muting

system? B.S. I think it's a conspiracy. The truth is, they make it ridiculously loud so you can't possibly

fall asleep. Fall asleep and you may move. Move, and it's time to start over. See? That was easyand

believable. Magnets, my ass. Oh, by the way, I still don't believe Oswald acted alone.

Former MRI tech here - and the simple answer is that the metal ring in/on aorta or wherever would

likely experience a torque/twisting-effect when the person is placed within the field (which is always

'on'). When the various imaging sequences are begun, the changing forces of torque upon the metal

can easily cause the ring to bend/move as a whole and possibly tear it out of its normal place. It is

also possible to have an induced current produced in circular objects (like rings on hands or things

within body like pacemaker leads that happen to have looped during placement, etc). I've had plenty

of patients tell me their finger's rings (platinum, gold, titanium,whatever) got warm during scan

sequences along with them feeling it trying to turn in various directions/alignments upon their finger

while the field was being changed rapidly by scan parameters.

Even non-ferrous items can experience the torque of attempting to line up with the magnetic poles;

an aluminum ladder I used to access top of the gantry would try to rotate in my hands as I moved it

from one side of gantry to other. Rather odd feeling as one end of 10' tall ladder would be pulled

more than other, but not towards magnet - just a rotation-type movement. There was one nurse who

had a necklace with lots of plastic 'charms' that had some type of shiny metal 'paint' upon them, and

whenever she would come to start a difficult IV in scan room, all the charms on her

necklace/bracelets would turn and align in same direction but not noticeably being pulled toward

gantry at all.

It is usually the torque effect that affects things first (noticeably anyways), and of course there are

instances of getting ferrous stuff too close and then becoming missiles flying to the magnet. Surgical

implants are always a big worry mostly due to the torque of objects trying to align with field, and if

they are shaped in a loop or such then 'electrical effects' like heating of the metal from induced

current are worrisome.

Hope I made some sense...

Duke of York, chances are you would get rather torn up internally. My mom, who is a nurse, told

me a story about her hospital where another patient's O2 tank, in the next room, hit the wall nearest

the MRI room due to the magnetic flux. I've no doubt the story was exaggerated (aren't those

machines/rooms shielded? what about pens/clipboards/electrical plugs/gurneys in the radiology room

itself?) but you definitely do not want to get an MRI with your hardware. My husband forgot his

wedding ring for his, and even though it's mostly gold, had to stop the procedure so he could remove

it due to his hand vibrating.

My father-in-law is one of the directors of a company which makes sophisticated / sensitive metal

detectors, specifically for MRI suites. MRI suites are, in theory, shielded to prevent issues with metal

items outside of the suite, but some may be better than others. Within the suite, you don't want any

ferrous metal, and other sorts of metal can be problems, as well. Even small items can become

projectiles, or become heated by the magnetic field.

Noise Survey to Sydney Medical Practice

by Carl Strautins

in Noise Surveys

27 Jun 2014 | 0 Comments

Noise survey within MRI control room

Safe Environments were engaged to undertake a preliminary noise survey at a medical centre to the

south west of Sydney. The purpose of the preliminary noise assessment was to assess the noise that

was being produced by a new piece of medical equipment, an MRI. MRI is an acronym for Medical

Resonance Imaging (MRI). The medical device uses powerful magnets and radio waves which

provides images of the body.

There were concerns as the noise level of the medical equipment and a noise survey was conducted.

The concern was of the diagnostic staff who work with the patients and move in and out of the room

on a regular basis. While this appears to be a simple process of measuring the noise levels, the

problem was that no metal objects can be in the same room as the MRI. This is due to the powerful

magnets that may pull away any metal objects and pose a hazard.

During the operation of the MRI the staff are to wear hearing protection, however the main concern

of the noise was the extended period of time that the health practitioners may have been exposed to

whilst being within the control room. To assess the noise levels within the control room a couple of

dosimeters were used.

The dosimeters were decided to be used to provide the overall daily noise exposure that is likely to be

anticipated over the day. The graphical log was also able to identify periods where the noise was

perceived to be higher than usual. It was explained that some certain scans would provide a higher

noise levels, therefore the noise survey should be taken over the length of an entire day, rather than

just over a scan or two.

There consideration that the staff could wear the dosimeter within the control room and then take

them off before entering the MRI room. This however was decided against as there was a high risk

that the staff may forget to take the dosimeter off before entering the MRI room again.

The results of the dosimetry provided evidence that the noise, whilst being perceived as being high

by the workers, was well below 80 dB(A) over the length of a shift. This indicates that no additional

controls were required to be put in place and Personal Hearing Protection (PHP) was not required.

The end result was that the workers were now happy to know that the noise levels that they are

exposed to within the control room will not be detrimental to their hearing and that this has been

documented to show that the control room have noise levels below the NSW workplace health and

safety exposure standards.

Please contact Safe Environments for more information on noise surveys to assess your workplace is

compliant with noise exposure levels.