coustic Shielding Solutions for §] PSffl Installations An ESCO Technologies Company

The Issue: Increasing Noise Levels in MRI Environments With the introduction of more powerful gradient coils on today’s high field MRI scanners, MRI equipment is producing increasingly high noise levels. During a typical scan sequence, many newer MRI systems will produce average sound pressure levels (SPL) as high as 100 to 110 dBA, with peak levels of 120 dB. These high scanner noise levels can interfere with patient comfort, patienttechnician communication, and staff working efficiency. noise suppression specifications often exist During a scanning procedure, the patient is located at the epicenter...

Understanding Sound Transmission Following are descriptions of Sound Transmission Loss (STL) and Sound Transmission Class (STC) ratings. Sound Transmission Loss (STL) Airborne sound is transmitted through a barrier in much the same manner as is a radio frequency signal. When a sound wave traveling through the air strikes a barrier surface, most of the sound energy is either reflected back into the source room or absorbed in the barrier, but some of the sound energy penetrates the barrier and is detectable in the receiving room. As sound penetration occurs, the sound wave exerts a fluctuating...

Designing for Acoustically Enhanced Rooms Most acoustic noise is airborne and not only affects patients and technicians in the room, but also travels through walls, floors, ceilings, and structural gaps to affect persons in adjoining spaces. (For structure-borne noise problems, see the section on “Isolation for Structure-borne Noise,” Page 8). ensure that no issues are left unattended. Acoustic noise abatement is made possible with a combination of conventional building materials, fiberglass panels, mineral board fillers, mass loaded vinyl, sealants, and absorbent linings for ducts. In this section,...

Designing for Acoustically E n h a n c e d R o o m s CONTINUED lessen the effects of sound reverberation in the Magnet Room. The measured sound levels within the space via a sound level meter will not change. However, the measured sound levels can only be reduced when the sound level generated by the MR system is reduced. Sound quality (reverberation) improvements can be achieved through the following methods: • Using ceiling tiles with fiberglass panels having a 2-in. (51mm) thickness set into the standard T-bar grid system. Adding fiberglass panels to the sidewalls covering approximately 20%...

Air Gap RF Panel w/ Sound Insulation Fill Acoustic Tile Drop Ceiling Studs or Resilient Furring Channel Deck, Parent Ceiling Ceiling Support Copper Shield Layer 5/8 in. Drywall w/Optional 2cd Layer Seams Sealed with Non-Hardening Acoustic Chalk Copper Shield RF Panel w/ Sound Insulation Fill 3 5/8 in. Stud 5/8 in. layer Drywall Vibration Isolation Pad Located at Magnet Underlayment Copper Shield Epoxy Adhesive Epoxy Isolator Parent Floor

Designing for Acoustically Enhanced R o o m s CONTINUED treatments. The cavity wall should be filled with fiberglass insulation. Two layers of 5/8 in. GWB should be applied as the interior surface finish. Follow the above recommendations for the application of acoustical caulking. Air Ducts. Ventilation ductwork can carry unwanted noise from the MRI room to surrounding rooms. Two solutions are recommended: • Line the air duct walls with a thick, absorbent material. Place intermittent baffles within supply and return ducts. Plumbing, Penetration Panels, RF Windows, and RF Doors. The following...

Acoustically Rated ETSLindgren RF Doors While most RF doors provide little in the way of acoustic performance, ETSLindgren’s acoustically rated RF doors have been developed and fully tested to deliver outstanding STC ratings for sound abatement. These acoustically enhanced versions of standard MRI RF doors feature proprietary designs on both the door leaf and perimeter jamb area seals that provide the highest STC rating. Without acoustically rated designs, it would require an expensive, massive, and difficult-to-use door to achieve a favorable sound rating in an RF door. By contrast, the specially...

acoustic inserts may be placed in all wall and ceiling surfaces. When used with STC 50+ rated parent wall assemblies, without penetrations, the RF shield wall and ceiling assemblies are capable of contributing additional STC rating points between 10 and 30, depending on the type of interior wall preparations provided by the customer and the type of shielding material. This contribution would be made to the entire acoustic assembly, consisting of parent walls/ceiling, RF shield acoustic modification, and finished interior walls. Acoustic Floor Systems While the thickness and construction of MRI...

each of these floor systems depending on site conditions and particular isolation requirements. Acoustic Absorption Kits for RF Shields As an option, ETS-Lindgren offers sound absorption kits that can be applied directly to the RF shield walls and ceiling. The addition of one of the kits to the RF shield, when no other acoustic construction methods have been instituted to the overall construction of the MRI room, will have only a limited effect on total noise control of the MRI resonator. One must keep in mind that the bulk of the noise reduction control remains with the primary building structures,...

Airborne Sound- Sound transmitted through air as a medium rather than through solids or the structure of a building. differentials are measured in one-third octave bands and compared with standard contours as per ASTM E 413. Attenuation, Sound- Reducing the intensity of a sound signal. Noise Reduction (NR)- The difference in sound pressure level between any two points along the path of sound propagation. As an example, noise reduction is the term used to describe the difference in sound pressure levels between the inside and outside of an enclosure. Noise reduction is usually expressed as a function...