LEUVEN, Belgium, Aug. 30 (UPI) -- Rather than relying on computer models or guesswork, doctors may soon be able to monitor the efficacy of radiotherapy against cancer using microbubbles that stick to the surface of tumors.
Researchers at the University of Leuven have developed a system using gas-filled microbubbles and ultrasonic sound waves to determine if radiation has reached targeted areas of the body, which could help reduce damage to healthy tissue around tumors.
The use of microbubbles as a contrast agent for imaging is not a new idea, as they were being experimented with widely in the late 1990s and early 2000s to enhance ultrasound imaging.
Microbubbles work by resonating in an ultrasound beam, contracting and expanding in response to pressure from sound waves, allowing them to be differentiated from other tissue. The bubbles are used for imaging tissue and organs, as well as drug delivery and gene transfer.
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When radiotherapy is used as part of cancer treatment, doctors rely on computer simulations and measurements outside the body to determine whether beams of radiation have hit their tumor targets while minimizing the exposure of healthy tissue.
The technique developed by researchers at the University of Leuven starts with the injection of gas-filled microbubbles into the bloodstream, where the tiny bubbles seek out and bind to the surface of tumors.
"We send ultrasonic sound waves to the gas-filled microbubbles, which makes them vibrate at their natural frequency," Koen Van Den Abeele, a professor in the department of physics and astronomy at the University of Leuven, said in a press release. "We then measure the vibration of the microbubbles before and after the radiotherapy. If the radiation has reached the targeted area, the microbubbles will have become stiffer and thus vibrate at a higher frequency. The change in frequency and attenuation is a measure of the radiation dose."
Researchers at the university have already received a patent for the technique, and tested it in lab experiments and with mice, but say more research is needed before testing the microbubble method in humans.
