Siemens has made substantial changes in the design and layout of its magnetic resonance imaging equipment over the past few months. The vendor is suggesting changes in computer layout, console design and radio-frequency shielding configurations for existing users, said Morris Stein, president of the Stein-Cox Group of Phoenix. Stein's architectural firm specializes in MRI design and siting.
The goal of these equipment and siting design changes is to save space. MRI vendors are attempting to place their scanners in spaces that were not considered feasible in the past, Stein said. In some cases, the spaces remain infeasible.
"The reality is that there are a number of places you cannot put an MRI (system)," he said.
Stein-Cox has also witnessed an increase in demand for Siemens and Picker MRI systems, in large part due to the popularity of the active-shield magnets built by Oxford and used by both vendors (SCAN 2/13/91).
"We are seeing people who would never have thought of looking at Picker now buying Picker. It is due to (Picker's) overall (MRI) technology. They seem to be working hard at it," Stein said.
The architect has encountered unexpected problems in working with active-shield magnets, however. Large, moving steel objects, such as elevators or outside vehicular traffic, apparently interfere with the magnets even though the objects are located where the gauss fringe field would normally be at sufficiently low levels.
MRI site designers must ensure that such moving objects remain a set distance from the magnet, regardless of the fringe field, because magnetic fields are neutralized by active shielding but not absorbed, as with steel shielding. The magnetic field may still be present even though it has a zero value, Stein said.
