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IMEDCO MRI Shielding Having installed more than 4500 shielded enclosures in over 40 countries worldwide, IMEDCO is mastering the complicated world of MRI Shielding.
| healthcare architecture
ABOVE & LEFT: successful MRI Shielding package is one that provides the necessary barriers to protect the magnet and environment from radio-frequency interference, protects the surrounding areas from unwanted magnetic fields and acoustic noise, and supports required services into and out of the shield without compromising personnel access and control of the patient. BOTTOM LEFT: Special window design that includes 3 panes and special shadow box design provide clear viewing of patient and 55dB noise reduction. BOTTOM RIGHT & OPPOSITE: Hidden behind traditional finishes, the IMEDCO shield panels and components are designed, constructed and installed using physicsâ€™ principles and proper materials selection. Layering techniques of these effective materials, covered under US patents, provide the desired results. All photos courtesy of IMEDCO America, Ltd.
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Having installed more than 4500 shielded enclosures in 40 over countries worldwide, IMEDCO is mastering the complicated world of MRI Shielding. by William Coleson
Magnetic Resonance Imaging (MRI) remains a sophisticated and very effective diagnostic tool after 30 years of both clinical and research applications. Although numerous advances have been made by the equipment designers, there remains an issue that still challenges today’s architects and users: the equipment’s impact on the surrounding environment. The device requires various types of shielding. These include traditional radio-frequency (RF) shielding which is mandatory for proper operation of the equipment; magnetic shielding that may be needed to protect the adjacent areas from the powerful magnetic field; and acoustic shielding which is necessary to isolate areas near or connected to the suite from the high levels of acoustic noise that the equipment generates. IMEDCO America Ltd. is one of the few companies addressing all of these complicated issues. The company is a division of IMEDCO AG, a Swiss shielding company founded over 30 years ago. The division has design, manufacturing and marketing resources and is located just north of Indianapolis. All clinical MRI exam rooms and some research centers require RF shielding because MRI machines rely on radio signals to excite atoms and chemicals within the body, which are identified and analyzed to produce information for imaging anatomy or spectroscopic data. The signals transmitted are very precise and are in a range that could be affected by TV and radio stations, some cell phones and 2-way radio signals. Similarly, the magnet’s signal can interfere with some of those outside signal sources. Therefore, a shield is required to create a barrier between the Scan Room that has the device and the environment. This shield must have a minimum measurable performance in accordance with magnet vendor requirements to decrease or attenuate these signals such that they will not affect the equipment. Since this equipment often includes a very powerful superconductive magnet, magnetic shielding may be necessary to ensure that no one is 0inconvenienced by anything from the simple erasure of credit cards to the more serious functionality of a pacemaker. The strength of these magnets, measured by Tesla, is remarkable-- ranging from 60,000 to 320,000 times the strength of the earth’s magnetic field. The appropriate
magnet strength is determined by the application and venue, such as a hospital versus research laboratory. Today, acoustic shielding is a major consideration because as MRI technology advances the newer magnet gradients are producing higher noise levels. The areas adjacent to an exam room are likely exposed at times to noise levels of 110-120db—the same as a lawn mower or chain saw. Although the intensity decreases with distance, issues can arise if design steps are not taken to ensure that critically occupied areas near the MRI suite (patient recovery, surgical suites, reading rooms, lobbies and patient waiting areas) are not adversely impacted. Mike Krachon, General Manager for IMEDCO America Ltd., reports that their company made a major commitment to understand all aspects of these shields and, in particular, how noise issues may be addressed. They have developed designs that can be used in conjunction with traditional MRI shielding packages to address the negative impact these important diagnostic tools have on a hospitals or medical office buildings. Today’s MRI shielding packages rely on pure physics to produce the most effective barriers. Material types and construction methods are developed to maintain this barrier but still provide all the necessary functional needs within the exam room such as lighting and HVAC ducts, sprinklers, medical gas access, patient entry doors and viewing windows. Choosing the optimum RF shielding medium; determining and then surrounding the shield with the appropriate thickness and positioning of the magnetic shield (low carbon plates or multiple layers of electrical/ silicon steel material) to suppress the magnet’s field 3D magnetic model; and understanding how a combination of different layering within the shield panels can achieve predictable acoustic benefits are paramount to each parameter selection. A thorough understanding of available, proven techniques that provide the best environment in MRI suites and their surrounding areas can have very positive effects on space-planning and balancing the trade-off of all the different options. IMEDCO is one of the few companies today that has investigated the effect these combinations have on the containment and barriers of all three types of MRI shields. “We have done studies that involved a variety of materials and layering techniques combined with our RF panels and had them tested in independent laboratories to understand what absorbing levels they can offer,” said Krachon. “We can pretty accurately predict the amount of acoustic noise that may be heard in the adjacent spaces using our designs.” IMEDCO currently holds several U.S. Patents involving acoustic and RF combination designs. IMEDCO’s dedication to customer satisfaction is evident by its’ inclusion of basic acoustic shielding within the RF shielding package, its’ unique ability to offer a complete MRI shield solution, its’ extensive experience in providing full solution packages throughout the world and its’ extensive warrantees on all shielding devices. “We can provide a total shield package for any site design,” Krachon said. “More value and benefits are offered for less total construction costs to the clients, the architect and the general contractor.” ALT Fall 2010 3
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