The radiation dose of an X-ray scan is fine for patients getting them every now and then, but health risks stack up for radiologists who are exposed to it all day, every day. Layers of protective gear help, but now researchers at Purdue University have developed a living device for these workers, using yeast colonies in wearable patches to monitor how much radiation a person is being exposed to.

Although measures are taken to reduce the radiation levels that radiologists are exposed to, it's not completely foolproof. Small doses are inevitably still going to be absorbed by the body, and while those are mostly harmless individually, over the span of years that can translate to a higher risk of conditions like cancer.

"Currently, radiology workers are required to wear badges, called dosimeters, on various parts of their bodies for monitoring their radiation exposure," says Babak Ziaie, an author of the study. "They wear the badges for a month or two, and then they send them to the company that made them. But it takes weeks for the company to read the data and send a report back to the hospital. Ours give an instant reading at much lower cost."

The new design uses yeast as a canary in the coal mine, so to speak. The idea is simple: A yeast colony is enclosed inside a badge made of freezer paper, aluminum and tape, and worn while the person goes about their business in the lab. Afterwards the badge is scanned, and radiation levels can be determined by counting how much of the yeast population has died.

To figure out how many yeast cells are still alive, users add a drop of water to the device and then attach it to a readout system that measures how well the yeast conducts electricity. Essentially the more yeast that's alive, the more ions are produced at the badge's surface, which makes the device a better conductor. If, however, the colony has taken heavy casualties from higher radiation doses, the conductivity will drop.

"We use the change in electrical properties of the yeast to tell us how much radiation damage it incurred," says Rahim Rahimi, an author of the study. "A slow decrease in electrical conductivity over time indicates more damage."

The researchers say the new devices can detect radiation doses as low as 1 millirad, which is similar to what current dosimeters can do. In future, the yeast badges could be adapted for workers in nuclear power plants or disaster victims, and the readout device might one day be just an app on a phone.

The research was published in the journal Advanced Biosystems.

The team describes the work in the video below.

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