Playing The Angles

December 21, 2007
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GRAND RAPIDS — Saint Mary’s Health Care has secured its first patent and, with help from the West Michigan Science and Technology Initiative, is in the process of licensing a hallway design that allows radiation treatment to occur in rooms without doors.

WMSTI Director Linda Chamberlain said the patent is the first for her organization’s Biotech Commercialization Project. Members include Grand Valley State University, Mary Free Bed Rehabilitation Hospital, Michigan Medical PC, Saint Mary’s, Spectrum Health and the Van Andel Institute.

Usually radiation treatment rooms require walls of 9-foot-thick concrete and heavy, slow-moving metal doors to prevent leakage of radiation into public areas. Too much radiation can be harmful to people who don’t need the treatment.

Medical Physicist Tewfik Bichay, working with architects who designed the hospital’s Lacks Cancer Center, developed a 26-foot, L-shaped hallway with specific angles built in that prevent radiation escape. Instead of 3,000-pound metal doors — which make patients feel entombed and have been known to trap them inside or to ensnare technicians — Lacks’ three radiation rooms are open all day. A set of wooden doors at the entrance is closed and locked only to prevent access at night. No other radiation rooms in Michigan operate door-free, Bichay said. The Lacks Cancer Center opened in 2004.

Bichay, whose job is to design radiation treatments for cancer patients, used his knowledge of mathematics and the behavior of neutrons and protons to determine angles that prevent radiation leakage.

After two years of work by Bichay, Director of Innovation and Research Susan Hoppough, WMSTI and lawyers from Saint Mary’s corporate parent, Trinity Health, the patent was issued in November.

“What we’re looking at is a licensing agreement,” Hoppough said. “We know that there are companies that are in the business of developing rooms for radiation and oncology departments. And we believe that this design is unique and certainly has value in other companies, so we will work toward developing that licensing agreement with a business that does that work.”

Door-free radiation rooms are used elsewhere, Bichay noted, for example, in Florida and in Europe. But they have straight hallways as long as 40 feet, making for unhappy radiation therapists who must traverse the length many times each day.

“There is a safety concern, too,” he added. “When you have a big door that has to open and close, imagine the torque on those hinges: It’s huge. The door will eventually break. If the door breaks in the open position, you’re just not going to use that room until it gets replaced. If it breaks in the closed position, there’s a patient inside that’s trapped.”

Busy radiation technicians often try to squeeze between the heavy doors in an effort to save time. But, Bichay said, technicians have lost arms that were trapped between the doors or have even been crushed to death.

The doors also create a delay should hospital personnel need to reach a patient who is claustrophobic or having some other problem, Bichay said.

Bichay said he spent about six weeks in 2003 working out calculations on paper and with computer help for the Lacks hallway, also called a maze.

The first reaction from architects was thumbs down.

“Their idea was to have a room with no maze at all and just a huge door,” he said. “It didn’t solve any of the issues that were brewing in my head at the time. We started off really on opposite ends of the fence.”

The angles not only had to deflect radiation, but the maze could not be so convoluted that it prevented 16,000-pound linear accelerators or hospital beds from making the journey, he said.

Once Bichay settled on an angled-wall design, he contacted a leading expert in radiation shielding. “I sent him a prototype of my design, and he said ‘It won’t work.’ I can’t tell you how that made me feel,” Bichay said. Another expert gave it a 50-50 chance.

Saint Mary’s decided to use Bichay’s design anyway. Annual tests have showed that the design works, he said.

“I’m really impressed with Saint Mary’s,” Bichay said. “They said, ‘This sounds creative. Let’s go ahead and give it a shot,’ and that really says a lot about the hospital.” Saint Mary’s also has agreed to share with him profits from licensing the design.

Another part of the challenge was to find a way to squeeze three radiation therapy rooms into the cancer center’s basement despite space constraints created by the old Xavier Hall basement and a tangle of underground tunnels. Fifteen feet separated the floor of the radiation rooms from the floor above, and the conventional 9-foot thick concrete walls would leave just six feet for people and equipment.

Bichay turned to interlocking bricks made from a type of concrete that has an increased density due to the addition of metal pieces. That allowed walls and ceilings to shrink to 4 to 4½ feet thick. While the concrete stops photons, the metal-stud walls also contain special plastic sheets that attract and absorb harder-to-contain neutrons. The walls also contain steel and lead. They are covered in drywall painted a soft yellow.

“It’s really difficult to calculate exactly what neutrons might do as they come around corners. There is no good model yet to do that,” Bichay said.

“It wasn’t until we fired up the first machine and did measurements that we were certain this was going to work.”    

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