Precise 3D images make it possible to track radiation, used to treat half of all cancer patients, in real time.
By capturing and amplifying the tiny sound waves created when X-rays heat the body’s tissues, medical professionals can map the radiation dose within the body, giving them new data to guide treatments. It’s the first-of-its-kind view of an interaction that doctors hadn’t been able to “see” before.
“Once you start delivering radiation, the body is pretty much a black box,” says Xueding Wang, a professor of biomedical engineering and professor of radiology who directs the Optical Imaging Laboratory at the University of Michigan.
“We don’t know exactly where the X-rays hit inside the body, and we don’t know how much radiation we’re delivering to the target. And every body is different, so making predictions for both is tricky,” says Wang, corresponding author of the study in Nature Biotechnology.
Radiation is used to treat hundreds of thousands of cancer patients each year, by bombarding an area of the body with high-energy waves and particles, usually X-rays. Radiation can either kill cancer cells directly or damage them from spreading. .
These benefits are undermined by lack of precision, since radiation treatment often kills and damages healthy cells in areas surrounding a tumor. It can also increase the risk of developing new cancers.
With real-time 3D imaging, doctors can more precisely direct radiation toward cancer cells and limit exposure to surrounding tissue. To do that, they simply need to “listen.”
When X-rays are absorbed by body tissues, they are converted into heat energy. That heating causes the tissue to expand rapidly, and that expansion creates a sound wave.
The acoustic wave is weak and generally undetectable by typical ultrasound technology. The new ionizing radiation acoustic imaging system detects the wave with an array of ultrasonic transducers positioned on the patient’s side. The signal is amplified and then transferred to an ultrasound device for image reconstruction.
With the images in hand, an oncology clinic can alter the level or trajectory of radiation during the process to ensure safer and more effective treatments.
“In the future, we could use the information from the images to compensate for uncertainties arising from positioning, organ movement, and anatomical variation during radiation therapy,” says first author Wei Zhang, a biomedical engineering researcher. “That would allow us to deliver the dose to the cancerous tumor with pinpoint precision.”
Another benefit of the new technology is that it can be easily added to existing radiation therapy equipment without drastically changing the processes doctors are used to.
“In future applications, this technology can be used to personalize and tailor each radiation treatment to ensure that normal tissues are maintained at a safe dose and that the tumor receives the intended dose,” says Kyle Cuneo, associate professor of radiation oncology. in Michigan Medicine.
“This technology would be especially beneficial in situations where the target is next to radiation-sensitive organs, such as the small intestine or stomach.”
The University of Michigan has applied for patent protection and is looking for partners to help bring the technology to market. The National Cancer Institute and the Michigan Health and Clinical Research Institute supported the work.
Font: University of Michigan
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