NIST Industrial Impact

Company: HT Medical Systems Inc., Gaithersburg, Maryland
Business: Medical Simulation Technology
Number of Employees: 60

Virtual reality is sometimes better than reality. Just ask airline pilots, who use flight simulators to practice handling windshear. If the virtual aircraft is thrown to the ground by a severe downdraft, then nobody gets hurt.

Not so in medicine, where gritty reality has been the teacher. Surgeons learn by practicing on cadavers and animals, for example. And when simulation is used—such as when nursing students practice inserting a needle into a plastic arm—the lack of realism reduces the effectiveness of the training. These imperfect methods can have costly side effects, such as medical complications in patients and even lawsuits over poor training.

But patients and trainees can rest easier now, thanks to HT Medical Systems, Inc., of Gaithersburg, Md., which has introduced lifelike virtual reality (VR) into medical training. With co-funding from NIST’s Advanced Technology Program (ATP), the small company developed software for authoring VR applications, as well as robotic devices for tactile feedback, that are helping to enhance medical training around the world. For example,

• spin-offs of two ATP projects include four products, three of which are already used in six countries, and a new VR company in the fitness industry;
• products are reducing nurse training costs, encouraging practice, and accurately assessing procedural skills, studies by users show; and
• other benefits include less trauma for human patients and reduced use of animals in medical education.

This success has enabled HT Medical to increase revenues substantially, attract millions of dollars in private investments as well as follow-on grants from other federal agencies, and nearly quadruple in size to almost 60 employees. All the attention is a testament to the new products’ unusual levels of physical and physiological realism.

“The technology enables people to learn how to do medical procedures without putting patients at risk,” says Greg Merril, HT founder and chairman. “We can also train
practitioners who don’t see a large number of patients to overcome the learning curve.”
The company’s first ATP award, for a three-year project that ended in 1998, enabled HT to expand the functional range of the technology and package it into an authoring tool that could be used to quickly design models of human tissues. In the ATP project, company staff developed the capability to model the cutting and bleeding of human tissues, designed input devices to model commonly used surgical tools, and wrote computer code to generate photo-realistic images of key processes in real time. The virtual anatomy and medical devices react to forces and gravity based on Newtonian physics—just like in the real world.

Merril compares the resulting software suite to a printing press for medical VR. Like the printing presses of yesteryear, it was selected by the Smithsonian Institution for the permanent collection of the National Museum of American History. “The ATP funded the enabling technology that allows us to create and integrate content into medical simulators. Everything we do now is based on the ATP work,” Merril says.

One component of the technology has been commercialized to date. Billed as the world’s fastest interactive volume-visualization software, it turns sequential two-dimensional (2D) pictures, such as computed tomography (CT) or magnetic resonance (MR) images, into three-dimensional (3D) anatomic structures. It also has a plug-in architecture to support custom options. Users can visualize either patient-specific data or full-color data from the National Library of Medicine’s Visible Human Project®, which contains CT, MR, and cryosection images of representative male and female cadavers.

HT Medical’s volume visualizer costs much less than competing products, according to Bob Morreale, a medical illustrator at Johns Hopkins in Baltimore. He selected the technology to transform 2D microscope slides of human embryos into 3D structures. “We have been able to extract meaningful information from our generated volumetric data sets,” he says.

HT Medical has used the authoring tool to make three products incorporating both visual and tactile elements. The first was a VR system to teach nurses the cognitive and motor skills needed to insert a needle properly into a vein. Commercialized in 1998, the system includes a force- feedback device that simulates how the procedure feels; it even says “ouch” if the trainee makes a mistake. The concept and much of the content were contributed by Plattsburgh State University of New York, which selected HT Medical to design the system after hearing a presentation on the VR authoring software. More than 200 copies have been installed around the world so far, and HT’s revenues from this product are growing at 47 percent per quarter.

“It is a real success story,” says Virginia Barker, a professor and director of VR simulation at Plattsburgh. Barker’s research shows that HT Medical’s simulator is less expensive than plastic arms ($45.55 per student compared to $53.50) because it doesn’t require costly faculty and staff time. She thinks it is more effective, too, because it presents students with a full range of potential complications, offers consistent and objective evaluations, and encourages longer practice sessions. The simulator also is required training at the University of Maryland School of Nursing, which did not even teach venipuncture until this product was available, according to Debra Spunt, manager of the clinical simulation labs. “We all felt that it was the closest to reality that we had in any of our simulations,” she says.

In its second ATP project, a two-year effort that ended in 1999, HT Medical developed technol-ogy to simulate minimally invasive surgery, which helps to shorten hospital stays and reduce trauma to patients. Company staff designed computer models of the physics of wire dynamics (the basis for medical tool operation) and adapted its force-feedback technology to accurately replicate the “feel” of endoscopic and endovascular procedures. The ATP funding enabled the company to assemble the required expertise in physiology, anatomy, computer science, mechanical and electrical engineering, and art.

The first products based on these technologies, which use Visible Human data, were commercialized in 1999. Future versions will enable the use of patient-specific data. A study at the University of Maryland Medical Center found that the bronchoscopy simulator was able to differentiate among users who have different levels of training, suggesting that it can accurately evaluate competence.

The ATP funding has had numerous benefits, according to Merril. For example, it enabled the company to design technologies that balance realism with computational efficiency, such that the venipuncture and surgical simulators can run on personal computers instead of more costly graphics workstations. In addition, the ATP-funded research is being leveraged by several other projects, including one supported by the Health Care Financing Administration to benchmark simulation by capturing, ranking, and storing data on user performance. Merril also has formed a spin-off company, Sky Fitness Inc., to produce exercise bicycles described as “human-powered flight simulators.” Finally, he knows of at least one medical institution that now uses HT’s simulators instead of animals to train students.

May 2000