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Artist's Rendering of Kennedy Krieger Institute Clinical Research Building, 716 N. Broadway, that will house the Philips 7T Achieva MRI. The building will be located directly across Broadway from the Johns Hopkins Broadway Research Building, between the Metro station entrance and Madison Street. This is diagonally across from the KKI 707 N. Broadway Building where the Kirby Research Center's two 3T MRI's and offices are located. The 7T scanner will be housed in the north end of the basement level (toward Madison Street).
The 7T Magnex magnet used for this scanner is not self-shielding as are most superconducting 1.5T and 3T magnets used today in MR scanners. As a result a 440 ton (400 metric ton), 6 sided, steel shield box must be constructed to contain the magnetic field. This box forms the largest part of the MR examination room; there is an area of the exam room at the front of the magnet, that is outside the shield box called the RF Porch. Openings about 8 by 8 feet square in the front and back of the box allow passage into and out of the shielded area. The box walls are thickest (16 inches) at the center of the four walls that parallel the magnet's long axis (the 2 long sides and top and bottom), stepping down to 8 inches at the two ends. The steel used for the shield is an alloy that has high magnetic permeability and was annealed after the plates were formed and cut to size to further increase permeability. Since the magnet must be perfectly centered in the box, the box is sunken below floor level into the "MR pit". The bottom of the box is filled with concrete and high density foam blocks to form the floor the magnet sits on.
Due the the proximity of the Metro and heavy traffic on Madison Street and Broadway, the scanner needs to be isolated from vibrations. The entire MR examination room, including the 440 ton shield with it's infill, the 35 ton magnet and all exam room interior finishes will be suspended on a Hammond Kinetics air spring isolation system. Twenty-six pressurized air springs will lift the room approximately 1/4 inch providing complete isolation from outside vibrations. Three level sensors regulate the air pressure in the air springs keeping the room level.
The air springs were set into place on March 4, 2008
before the concrete base that sits on the springs was formed
and poured. This allowed use of a fork lift to move the 300
pound air spring units into place rather than having to move
them by hand and hoist down the pit access shaft. This
concrete base is shaped like a giant bathtub, with a bottom
and four sides that come up the sides of the pit the reach
the finished floor level of the basement. The bottom
approximately 4 feet of the steel shield box will sit in this
bathtub.
Space under the "bathtub" in the bottom of the MR pit,
allows access to service the air springs. This is reached via
a vertical shaft with ladder and hoist in case one of the air
springs ever needs to be replaced. The springs are arranged
in 4 rows down the long dimension of the scan room, one row
along the left and right walls and a double row down the
center. Access aisles run along each row.
 MR scanner pit is complete; behind the basement walls are being formed and poured. |
 The supports for the air springs are being formed on the left, the center support is complete, the right is in place but still needs the raised blocks that support the bathtub when the air springs are deactivated. |
 Hammond Kinetics air spring installation, March 4. The air springs are stacked 2 or 3 high on the center support pier since the left and right piers are not completed. The support blocks are visible between each stack of air springs. These will support the concrete bathtub when the air spings are not inflated. |
 The forms for the bathtub are being constructed. The support blocks are left exposed and covered only with plastic so the bathtub will be siting directly on these blocks after the concrete is poured. The forms covering the aisles and air springs will be removed from below. |
 Completed forms for the outside of the concrete "bathtub" on March 14, 2008. |
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 Start of assembly of the magnetic shield (April 23) |
 440 tons of staged shield plates in the basement. Each plate is designed to weigh 10,000 lbs or less. |
 Stack of four 2 inch plates forming bottom of shield box - more layers will be added to center of box |
 Peter van Zijl (left) and Joe Gillen (right) of Kirby Center with Richard Lee of Shreveport, LA, the steel erector who is building the MR shield under contract with Imedco and Philips |
 Overhead view on April 24. You can see the opening in the basement wall through which the magnet will be rigged in late November. |
 Foam blocks are installed in the bottom infill space of the shield on May 2. This decreases weight on the air spring system compared to a solid concrete infill. |
 Poured concrete floor inside the shield is completed May 8. Wall assembly continuing. |
 Overhead on May 16. |
 Sides complete - beginning assembly of the top May 19. |
 Shield box complete, structural steel erection started, June 5. |
 7T Magnet being loaded at Magnex facility in Oxford, |
 England for shipment by boat to New York on November 1. |
 Crated and covered for transport. |
 RF porch copper shielding - projector waveguide and door to left, power line filters visible on ceiling |
 Framing started inside scan room |
 Magnet arriving at KKI on Saturday November 22 10:46am. |
 11:30am - 200 ton crane lifting magnet onto transport dollies |
 12:00 noon - Magnet being moved inside onto cribbing. The 100 ton jacks are visible that will lower the magnet down to the floor. |
 4:43pm - Almost down to the floor. |
 Sunday Nov 23 9:22am - Magnet moving toward scan room. |
 10am - Making the turn into the scan room. |
 11am - Only 2 inch clearance each side into the scan room. |
 500 liter liquid helium dewar being delivered. |
 Helium dewars staged for the magnet fill. |
 Control Room |
 Scan Room |
 Scan Room, RF Porch right - projector waveguide, shielded cameras and lab penetration panel visible |
 Scan Room, RF Porch left - projector waveguide, shielded cameras and coil storage visible |
 Equipment Room |
 Prep Room |
 Back of Scan Room - back wall of 400 tonne shield (red), projector (on table), 300kVA UPS visible |
 Back of Scan Room |
 fMRI Console (MRA, Inc.) for controlling video and audio stimulus and acquiring responses via fiber-optic buttons |
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 7T MRI Suite Floor Plan |
 Final RF Shield Test Results |
| Fence in Parking Lot, Demolition & Grading | 09/18/07 | 10/05/08 |
| Drill Sheeting & Shoring Piles and Caissons | 10/09/07 | 12/03/07 |
| Mass Excavation of Building Basement | 12/04/07 | 01/10/08 |
| Construct MRI Pit | 01/16/08 | 02/29/08 |
| Install Airbags | 03/03/08 | 03/05/08 |
| MRI Room Slab | 03/06/08 | 04/03/08 |
| Pour Basement Slab & Walls | 03/28/08 | 04/08/08 |
| Install 440 ton Magnetic Shield | 04/16/08 | 06/02/08 |
| Erect Structural Steel | 06/03/08 | 08/12/08 |
| Pour Elevated Slabs and Rooftop Slab | 08/13/08 | 09/12/08 |
| Exterior - Masonry, Roofing & Windows | 09/04/08 | 12/01/08 |
| 7T Magnet ships from UK | 10/01/08 | |
| Install MRI RF Shield | 10/02/08 | 10/26/08 |
| RF Shield Test | 10/27/08 | |
| Rig and Set 70,000 lb. 7T Magnet | 11/22/08 | 11/23/08 |
| MRI Suite Framing, MEP & Finishes | 11/28/08 | 01/31/09 |
| Magnet Installation by Magnex/Varian | 01/29/09 | 02/27/09 |
| Cryostat vacuum | 01/29/09 | 02/02/09 |
| Cryostat pre-chill with liquid nitrogen | 02/02/09 | 02/08/09 |
| Cryostat fill with liquid helium | 02/10/09 | 02/16/09 |
| Magnet ramping to 7T | 02/19/09 | 02/22/09 |
| Magnet shimming | 02/23/09 | 02/24/09 |
| Cryocoolers off due to chilled water system failure | 02/26/09 | 03/06/09 |
| Magnet radiation shield cool down | 03/06/09 | 03/20/09 |
| Magnet persistance and boil-off checks | 03/19/09 | 03/20/09 |
| Magnet acceptance | 03/20/09 | |
| MR Equipment Installation by Philips | 01/26/09 | 03/27/09 |
| Cabinets placed and cabled, magnet room cabled | 02/02/09 | 02/18/09 |
| Magnet covers, patient couch placement | 03/05/09 | 03/11/09 |
| Power test & pre cals ECC | 03/23/09 | 03/24/09 |
| Gradient ECC | 03/24/09 | |
| RF coil tests | 03/22/09 | 03/25/09 |
| Final system calibrations | 03/25/09 | 03/27/09 |
| PTS data collection | 03/25/09 | |
| Operational 7T Scanner | 04/02/09 | |
| 7T Training | 04/06/09 | 04/07/09 |