3D printing and neurosurgery.

Ed Smith does some fiendishly difficult surgeries. A paediatric neurosurgeon at Boston Children's Hospital, he often removes tumours and blood vessels that have grown in gnarled, tangled shapes. It's detonating -a-bomb-type surgery. Smith prepares for his work by using an unusual tool a 3D printer. Days in advance, hospital technicians use standard imaging to print a high-resolution copy of the child's brain, tumour and all. Smith will examine it for hours, slowly developing a nuanced, tactile feel for the challenge. "I can hold the problem in my hand," Smith says. "I can rehearse the surgery as many times as I want." During the operation, Smith keeps the printed brain next to him for reference. As a visualization tool, it's so powerful that it has reduced the length of his surgeries by an average of 12 per cent. Doctors have long used MRIs and CT scans to help visualize tumors. But when the visualization is physical, it has a haptic impact that screens do not. That's why architects build scale models of their buildings: only by peering around a structure do you "get" what's going on. "You see these spatial relations and depth of field that aren't possible on-screen," Smith says.Read