High power pocket ultrasound device opens way for new therapeutic uses
13 January 2009
A prototype of a therapeutic ultrasound device, developed by a Cornell University graduate student, fits in the palm of a hand, is battery-powered and packs enough power to stabilize a gunshot wound or deliver drugs to brain cancer patients.
The device is wired to a ceramic probe, called a transducer, and creates sound waves so strong they instantly cause water to bubble, spray and turn into steam.
George K Lewis, a third-year PhD student in biomedical engineering and a National Science Foundation fellow, creates ultrasound devices that are smaller, more powerful and many times less expensive than today's models.
Current ultrasound devices can weigh 30 pounds and cost $20,000; Lewis's is pocket-sized and built with $100. He envisions a world where therapeutic ultrasound machines are found in every hospital and medical research lab. "New research and applications are going to spin out, now that these systems will be so cheap, affordable and portable in nature," Lewis said.
The development of one of his portable devices is detailed in the November 11 issue of the journal, Review of Scientific Instruments (79-114302). Lewis, whose paper is co-authored by his adviser, William L Olbricht, Cornell professor of chemical and biomolecular engineering, also presented his research at the November meeting of the Acoustical Society of America.
Ultrasound is commonly used for medical imaging. But the higher-energy ultrasound that Lewis works with can treat such conditions as prostate tumours or kidney stones by breaking them up. His devices also can relieve arthritis pressure and even help treat brain cancer by pushing drugs quickly through the brain following surgery.
Lewis suggests that his technology could lead to such innovations as cell phone-size devices that military medics could carry to cauterize bleeding wounds, or dental machines to enable the body to instantly absorb locally injected anaesthetic.
Lewis miniaturized the ultrasound device by increasing its
efficiency. Traditional devices apply 500-volt signals across a
transducer to convert the voltage to sound waves, but in the process,
about half the energy is lost. In the laboratory, Lewis has devised a
way to transfer 95 percent of the source energy to the transducer.
Under the direction of Jason Spector MD, director of Weill Cornell's Laboratory for Bioregenerative Medicine and Surgery and assistant professor of plastic surgery, Peter Henderson MD, the lab's chief research fellow, is using one of the devices in experiments that aim to minimize injury that occurs when tissues do not receive adequate blood flow.
Their lab is performing tests in animals to determine whether low doses of the chemical hydrogen sulphide, known to be toxic at high doses, might be able to minimize such injury by slowing cellular metabolism.
Doctors are hopeful that the ultrasound from Lewis' portable device will enable hydrogen sulphide to be targeted to specific parts of the body, allowing doctors to use less of it, and cutting down on toxicity risks, Henderson explained.
The medical doors that Lewis' device may one day open are groundbreaking, Henderson said. "People are realizing that when harnessed appropriately, you can use ultrasound to treat things as opposed to just diagnose them," Henderson said. "It's a wide-open field right now, and George's device is going to play a huge role in catalyzing the discovery of new and better therapeutic applications."
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