After a nuclear or radiological accident, knowing who has been exposed to radiation—and how much—can save lives.
But traditional ways of measuring radiation dose usually rely on expensive equipment, trained specialists, or laboratory testing, which may be unavailable during large-scale disasters.
Now, researchers in Japan have developed a simple, low-cost system that can turn an ordinary smartphone into a practical radiation dose detector.
The new approach was created by scientists at Hiroshima University and reported in the journal Radiation Measurements.
It is designed specifically for emergency situations, where speed, affordability, and ease of use are critical.
The system combines three main components: a small piece of radiochromic film, a lightweight foldable scanner powered by batteries, and a smartphone camera.
The film used in the study, known as Gafchromic EBT4, is a special material that changes color when exposed to radiation. The darker the color change, the higher the radiation dose.
Unlike many radiation detectors, this film does not need electricity to work and reacts immediately after exposure.
In an emergency, the film can be worn on the body or placed nearby. Once exposed, it can be inserted into the portable scanner and photographed using a smartphone. A mobile image-processing app then analyzes the color change to estimate the radiation dose.
The researchers showed that this setup can measure radiation doses as high as 10 Gray. To give some context, a skin dose of around 10 Gray is severe and can cause permanent hair loss, making it an important threshold for urgent medical decisions.
While the system is not designed to replace hospital-grade instruments, it provides fast, useful information when professional tools are unavailable.
To ensure the system would work widely, the team tested it using different smartphone models, including both Android phones and iPhones. They found that results were consistent across devices, especially when focusing on the cyan color channel in the images. This consistency is important, as it means people would not need a specific phone model for the system to function properly.
One of the biggest advantages of the new method is its affordability. The entire setup costs less than 70 US dollars, making it realistic for large-scale distribution or personal emergency preparedness.
The system is also highly portable and does not depend on stable infrastructure, which is often damaged during earthquakes, floods, or other disasters that could coincide with a radiation incident.
The researchers emphasize that their goal is not perfect precision, but rapid decision-making. In a crisis, identifying who has received a dangerous dose—and who has not—can guide medical triage, evacuation, and treatment.
The team is now working on standardizing procedures and testing how well the system performs under different lighting and environmental conditions.
With further development, this simple smartphone-based tool could become a powerful aid in protecting people during radiological emergencies, putting lifesaving information directly into the hands of responders and individuals alike.
