Thermometers may be the perfect tool to measure your body's overall temperature, but taking the precise temperature of deeper tissues in the body is a little more challenging.
Researchers at Duke have been able to use photoacoustic imaging—a technique that combines light and sound—to efficiently take the temperature of deep tissue. Tracking deep tissue temperature is important for thermal-based cancer treatment research as well as other biomedical studies.
Junjie Yao, assistant professor of biomedical engineering, said that although MRI is capable of reading the temperature non-invasively, it is slow and expensive, and thus not practical for every patient.
“Photoacoustics are a combination of light and sound,” Yao said. “We use laser light to expand the molecules in tissue. When the light is absorbed by the tissue, we can form an image.”
In cancer therapies that aim to “cook” the tumor cells—thermotherapy—controlling the temperature allows doctors to destroy tumor cells without damaging healthy tissue, Yao explained.
“Our method is useful because tumors are usually deep inside the tissue, and it’s hard to measure temperature with traditional therapies,” he said.
Common methods of cancer treatment include radiation therapy and chemotherapy, but the quality of life associated with those options is often poor. However, thermotherapy with photoacoustic imaging can be used as a different treatment plan with the aim of maximizing treatment outcomes and minimizing side effects.
“This combination of light and sound can be easily combined with high intensity ultrasound treatment,” Yao said. “This way, we can treat the tumor while monitoring the temperature.”
Yao is working with Pei Zhong, professor in the department of mechanical engineering and materials science, to use high intensity focused ultrasound (HIFU) and photoacoustic imaging in tandem—a technique known as thermal-energy-memory-based photoacoustic thermometry (TEMPT).
With this technique, they can use the photoacoustic imaging technology as they're treating the cancerous tissues to measure the thermal memory of a tissue, which is how it can “remember” a temperature following a small change.
Currently, this research is being applied in the Duke Medical Center to patients with prostate cancer. Yao added that the Food and Drug Administration has already approved the use of HIFU for prostate cancer, as the prostate itself is also easily accessible by ultrasound, making it a prime target for this therapy.
He noted that the dynamic environment of tissue poses a major challenge to using this technology, in addition to several other confounding factors. The technology is working to maximize the potential of the TEMPT treatment for cancer patients and requires further research into the fundamental mechanisms, Yao added.
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“There’s no other technology like ours,” he said. “It’s much more practical than MRI because it just uses light and sound. It’s more accessible in most of the clinical settings. This technology is powerful.”