When using heat and other forms of radiation to ablate tumors, it is usually difficult to know just how hot the tissues around your target are getting, particularly when working deep within the body. MRI and ultrasound can be useful in many cases, but they have limitations and can produce misleading readings. To have a better option, researchers at Duke University have been working on using photoacoustic imaging as a tool to remotely measure the temperature of deep-seated tissues.
Photoacoustic imaging involves shining light onto an object, heating it ever-so-slightly, and then using ultrasound to detect the waves that result from the thermal expansion of the tissue. What’s interesting for this research is that the conversion of light via heat into sound waves is dependent on the temperature of the tissue being studied. The researchers used this fact to create a highly sensitive phototoacoustic system that can detect the differences in signals that the ultrasound measures when the tissue temperature changes.