The tremendous imaging power of computed tomography (CT) has helped transform medicine. But to date, CT scans have been beyond the reach of battlefield medics, ambulance crews, and even many emergency-room doctors.

That’s because conventional high-resolution CT scanners weigh almost 4,000 kilograms, require high-voltage power supplies for massive cooling systems, and must be installed in climate-controlled radiology suites.

The lack of quick access is a particular problem in cases of brain trauma or stroke, when speedy treatment is critical.

NeuroLogica, a startup in Danvers, MA, believes its small, rugged, and portable machine will make CT scans more accessible. “Our primary emphasis was on getting a CT machine in an ambulance and emergency-room setting for heads only,” says Bernard Gordon, the company cofounder, who estimates that 15 to 20 percent of CT scans are for the head and neck. “We need a machine they can afford all over the world that is rugged and can be worked by people with far less training than most radiologists.”

By 2005, a year and a half after NeuroLogica was founded, it had developed a machine suitable for emergency rooms and obtained U.S. Food and Drug Administration clearance for it; the company expects to deliver its first product this winter. It is now working on a version that could fit in ambulances.

The traditional CT scanner is a behemoth that looks like a giant point-and-shoot camera, with a hole in the middle instead of a lens. As a patient is conveyed through the hole, the machine continually shoots x-rays, and software combines the resulting images.

After Gordon and two cofounders started NeuroLogica in 2004, they set out to shrink the power supply and cooling system so they could use smaller x-ray-emitting tubes.

In whole-body CT scanners, these tubes can be 30 centimeters in diameter and 50 centimeters long. NeuroLogica’s engineers used tubes about 10 centimeters in diameter and 15 centimeters long. They created a power system about the size of a microwave oven, with a small fan to cool the tubes.

The combined miniaturizations let them reduce the diameter of the donut-shaped machine to 44 centimeters, while the “donut hole” stayed at 32 centimeters, large enough for a human head. The machine delivers the same resolution as large machines, but the scanning speed is slower: a head scan can take up to two minutes, considerably longer than with a traditional machine.

The second problem was how to make the machine move when scanning a stationary patient. The solution was a novel set of tanklike tracks. “I needed an electrical guy to give me a motor and drive, and a robotics guy to make sure it could cantilever properly over rough surfaces, and a software guy to guide it through its steps,” says Gordon.

Finally, the device needed to be very rugged and simple to use. Whereas big scanners must operate at room temperature in order to preserve image quality, NeuroLogica’s machine is designed for temperatures ranging from slightly less than 0 degrees C to 38 degrees C. It also includes a touch-screen interface that walks the operator through the scanning steps. All this in a 340-kilogram machine, light enough to be pushed by one technician and small enough to fit through a standard doorway.

“Neurologists are dying for a machine like this, especially in ICUs [intensive-care units],” says Walter Koroshetz, a neurologist and head of stroke and neurointensive-care services at Massachusetts General Hospital in Boston. “We need to be able to scan these patients in the unit, not 10 flights away, dragging along nurses and doctors and wires and equipment.”

Eric M. Bailey, another of the company’s founders, says building the machine didn’t involve developing new technology so much as essentially solving a complex packaging problem. It represents a leap beyond the previous best effort, heads-only CT scanners shrunk enough to fit into some ICUs but not portable or able to produce images that are up to today’s standards. Says Bailey, “Frankly, it’s just stupid people haven’t thought of it sooner.”