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This Radiation Scanner Is Custom Built for Fukushima's Babies

Scanners that are extra sensitive to radiation and young patients' needs.
Image: Hayano et. al

As you might expect, residents of Fukushima Prefecture have been concerned with radiation exposure since the 2011 earthquake and tsunami left the region's soil contaminated with radioactive cesium. Thankfully, extensive body scans have found very, very low rates of exposure in the community at large—or at least on those who can fit into radiation scanners.

Because babies and small toddlers can't reliably be scanned in adult-sized scanners, parents of Fukushima's youngest remain worried that their little ones have been exposed to radiation. In response, a team of researchers from the University of Tokyo and an American radiation-scanner firm have developed a body scanner that small children can play inside. Naturally, it's called BABYSCAN.

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In a paper published to the arXiv preprint server, the researchers explain that out of 21,785 Fukushima residents who were scanned with whole-body counters commonly used at nuclear facilities—imagine a body scanner like the ones at the airport, but which is highly sensitive to radiation exposureabout 1 percent of adults and "practically" 0 percent of children aged 6-15 had detectable exposure to cesium-137.

The researchers argue that "scientifically, it is sufficient to measure parents" for exposure. Yet they also note that current scanners—about 80 percent of those used in Fukushima Prefecture are FASTSCAN models made by Canberra, an American firm which counts two co-authors of the arXiv paper—have a lower detection limit of 300 becquerels (Bq) per body.

BABYSCAN in use at the Hirata radioactivity inspection center. Image: Hirata

That's a tiny amount of radiation—Japan's own guidelines for consuming vegetables contaminated by radiation put the top limit at 500 Bq per kilogram—but not sensitive enough for tiny children, who couldn't stand in the traditional scanner anyway.

"This detection limit is however too high for reliably measuring small children, since the biological half-life of radioactive cesium in children (13 days for 1-year old, 30 days for 5-year old) is much shorter than that in adults (110 days)," the authors write. "As a result, children's internal contamination is harder to detect.​"

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The goal then was to develop a scanner that could detect less than 50 Bq/body of cesium-134 and -137; because standing still for a two-minute scan isn't an option for toddlers, the team also needed to develop an enclosed scanner a baby could lie in without feeling trapped.

A cutaway of the BABYSCAN. Image: Hayano et. al

The scanner was designed instead to feature a bed that babies and toddlers can lie down on, either face up or face down. Apart from a viewing window, the machine is heavily insulated to try to limit how much background radiation is picked up by the highly sensitive sensors. In testing, the BABYSCAN was able to pick up cesium levels below that of the 50 Bq goal.

Following testing, the first model was installed at a Fukushima hospital last December. Bring on the good news: "Even with this low detection limit, radiocesium was not detected in any of the first 100 Fukushima children, while, as expected, 40K [radioactive potassium, which is found in all humans] was detected in all subjects," the authors write.

The finding is certainly heartening, and falls in line with a number of other studies that have found the radiation risk to be less than early predictions, which were based on the severity of the Fukushima-Daiichi disaster and comparisons to the Chernobyl aftermath.

"These results are consistent with those of many other measurements and studies conducted so far in Fukushima, e.g., rice inspection, foodstuff screening and duplicate-portion studies," they write, arguing that the region's contamination poses less of a risk than thought. It's certainly good news, but considering the culture of distrust bred by poor management and oversight of the disaster, Fukushima's parents aren't likely to rest easy until their own kids get scanned.

Watch: In the Fukushima Fallout, Meet the Hackers Building a Sensor Network for Global Radiation