Though people want a medical device or procedure to be fully tested before it is done on children or pregnant women, there is concern about actually doing the tests on those growing bodies. Shirley S. Wang reports in The Wall Street Journal that concern is just one reason why “virtual patients” are becoming the increasingly attractive research, diagnostic, and training tools.
Virtual patients are realistic-looking computerized models. They use medical data and computer software and graphics to mimic real people, with skin, bones, fat and organs of realistic size, shape and composition. Scientists are currently testing virtual patients to answer such questions as: How much radiation are various organs in the body exposed to as a result of a CT scan? How risky is it for a pregnant woman to get a scan? Should a heart device like a defibrillator be implanted in a child differently than in an adult?
Virtual patients could allow medical-device companies to test new products earlier, helping the devices get to market more quickly and cheaply, according to the Food and Drug Administration.
She adds that medical students could also use the technology to train for certain surgical procedures, and doctors could also use, for example, the 3D images of a pregnant woman’s pelvic region to calculate the risks associated with delivery of a fetus.
Wang highlights related work at Rensselaer Polytechnic Institute (RPI) in Troy, NY, and the Food and Drug Administration (FDA).
At RPI, X. George Xu and his team of nuclear engineers have been studying how radiation interacts with the human body for the past 20 years. His first model — essentially a plastic mannequin with sensors and no arms that still sits on his desk — is a lot different than the anatomically correct, sophisticated computer imagery that he uses now.
Xu knows that bodies absorb different amounts of radiation because bones absorb it and fat scatters it. Earlier this year, his team presented at a conference their virtual patient, which models fat distribution in a body and calculates how much additional radiation an overweight person requires during a medical procedure. “The aim is to administer sufficient radiation to achieve an image scan of adequate quality, but not too much to cause harm to the patient,” Wang writes.
Aipin Ding, also at RPI, is working on related software called VirtualDose, which examines how much radiation each organ receives after radiation from a medical procedure like a CT scan. Wang writes that these simulations could help doctors and patients to make clinical decisions, such as targeting tumors or “figuring out if the benefits to the mother in getting a CT scan outweigh the risks to the fetus.”
The video from Xu’s group suggests that similar technology could also be used for occupational monitoring:
At FDA’s Center for Devices and Radiological Health, Wang writes, researchers “have created a ‘virtual family’ of adults and children in order to study how best to implant medical devices in children, such as heart defibrillators.” (The anatomy of a child’s heart differs from an adult, and most research has been done on adults.)
FDA is also using virtual patients to help improve diagnostic techniques, such as heart catheterization, to detect the size and location of blockages, without risk to real patients in clinical trials.
Source: “Scientists Find Safer Ways To Test Medical Procedures,” The Wall Street Journal, 12/20/11
Source: “Using Computational Human Phantoms for Virtual Reality Simulation,” YouTube
Rachel Petkewich is a freelance science writer and editor. She has worked as a research scientist in the chemical industry and spent eight years as a staff writer and editor at various science journals and magazines, including Chemical & Engineering News.