CMU expert works on tool to train cryosurgeons
Dr. Yoed Rabin, a mechanical engineering professor at Carnegie Mellon University, has been awarded a four-year $1.3 million grant to develop a training tool for cryosurgeons to practice using "cryoprobes" to freeze and destroy cancerous or undesirable tissue.
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Practice makes perfect, as the saying goes. But what if practice isn't possible?
That's the challenge facing cryosurgeons who have no way to practice using "cryoprobes" to freeze and destroy cancerous or undesirable tissue.
With those challenges in mind, Yoed Rabin and Kenji Shimada, mechanical engineering professors at Carnegie Mellon University, are developing a computerized training tool to help cryosurgeons improve their techniques and realize better clinical results.
The National Cancer Institute has awarded them a four-year, $1.3 million grant to develop the training tool, which will use an interactive simulator to follow surgeons' actions throughout the procedure, provide tutorials and evaluate whether the surgeon succeeds in simulated surgeries.
The trick is placing cryoprobes so they produce a thermal field that freezes only targeted tissue, often in the prostate gland, but also elsewhere in the body.
Cryosurgeons often rely on experience, trained intuition and even some trial and error to create a thermal field to destroy diseased tissue. But it's difficult to tell whether the minimally invasive procedure, with ultrasound or other imaging technology serving as the only guide, actually is destroying targeted tissue.
Are there too many probes or too few? Are they placed correctly? Is the thermal field destroying all the cancer and avoiding healthy tissue?
Dr. Rabin is expert in biothermal technology and has been developing cryosurgical devices and related research techniques for the past 18 years.
Not included in the current project is his research involving preservation of tissue at lower temperatures, known as cryopreservation), that could be used to preserve tissues to be used in transplantation and regenerative medicine.
In a previous project, he also developed algorithms that could be used to help clinicians properly place cryoprobes used in cryosurgery. That method uses 3D images of the prostate gland and imaging devices, along with his algorithms or computerized programs, to help determine how many probes are needed and where best to place them.
The goal of his current project is to combine technology developed throughout his career and push it to the next level, which Dr. Rabin describes as an interactive computer simulation of cryosurgical operations that also evaluates outcomes.
"Cryosurgery has a unique difficulty," he said. "It creates a thermal region completely closed in the body. It destroys the tissue in the temperature field in an area surrounding the cryoprobe. The trick is to maximize destruction in the cancerous tissue and minimize destruction of healthy tissue."
Avoiding healthy tissue is key.
Dr. Rabin said he hopes the project will serve as a "revolutionary concept" to allow surgeons to practice procedures, improve their skills, realize better results and eventually reduce the cost of cryosurgery.
Dr. Shimada, in a news release, said the process will allow surgeons to place probes without risk to patients, visualize frozen regions with intuitive 3D computer graphics and benchmark their performance with hundreds of cases stored in a database. "It is a motivational and effective way of learning and improving their surgical skills," he said.
Dr. Shimada's expertise includes computational modeling and simulation for product design, engineering analysis and factory automation.
The tool could be used to train surgeons in all cryosurgeries, although the focus at this stage is prostate cancer. The American Cancer Society predicts 192,280 new cases of prostate cancer this year in the United States.
Recently, Dr. Rabin also has received a two-year, $430,000 grant through the National Institute of Biomedical Imaging and Bioengineering to lead a research team in producing wireless sensors to measure temperature fields in tissue during surgeries that use hot or cold temperatures to kill cancer.
Thermal sensors the size of grains of rice are in early stages of development, he said. The idea is to place them in targeted tissue to transmit wireless temperature readings to a computer. Surgeons then can better map temperatures in targeted areas during surgeries.
The sensors, he said, would be made of tissue-compatible materials.
"In many ways, these two projects complement one another, while aiming at bringing state-of-the-art technology to clinical practice," Dr. Rabin said.
First Published December 23, 2009 12:00 am