Researchers at Hiroshima University have developed a low-cost, portable radiation dosimetry system that turns a smartphone into a field radiation detector that can be used on-site to make immediate dose assessments after nuclear or radiation accidents.
This innovation comes at a time when Japan is cautiously re-embracing nuclear power to meet growing energy demand and achieve its climate goals, according to reports.
The system, detailed in the journal Radiation Measurements, combines a small piece of radiochromic film, a foldable battery-powered scanner, and a smartphone camera.
It is designed to provide rapid, individual-level dose assessments in mass casualty scenarios, where traditional laboratory-based methods may be slow, expensive or unavailable.
The study said that immediate assessment of doses at the individual level is necessary to protect people from the negative consequences of radiation exposure after large-scale nuclear or radiation accidents.
Lead researcher Hiroshi Yasuda, a professor at the Research Institute of Radiation Biology and Medicine at Hiroshima University, stressed the practical side of the work, saying: “To protect people in the event of a serious radiological or nuclear accident, voluntary field dose assessments must be conducted and rapid medical decisions made on the spot. Simplicity, universal usability, and low cost are crucial factors in these emergency procedures.”
At the heart of the system is the “Gafchromic EBT4” film, which changes color immediately after being exposed to radiation.
This change can be seen with the naked eye, but the system goes further, as it allows users to accurately measure the dose by scanning the film and taking its picture using a smartphone, then analyzing the color change via image processing applications on the phone.
The researchers showed that relatively high radiation doses, up to 10 gray (“Gray”), can be measured in this way. To illustrate, a dose of 10 Gy to the skin is sufficient to cause permanent hair loss.
In tests conducted using different models of smartphones, including Samsung and iPhone, the team found that the cyan channel in digital images provided the most consistent and reliable dose-response data.
Although professional desktop scanners remain more accurate, the smartphone-based system provides a practical balance between accuracy and accessibility. The complete system costs less than US$70, making it much cheaper than traditional dosimetry equipment, and it is also light and portable enough for use in disaster areas.
In this context, Yasuda said: “Our goal was to design a system that would work even in the worst accident scenarios, such as after natural disasters when infrastructure may be damaged.”
The team is currently working to standardize protocols and ensure system reliability in diverse environmental conditions.
Doctoral student Hasna Bintan and Professor Yasuda participated in preparing the study, and the costs of open access publishing were supported by Hiroshima University.
Energy strategy transformation
The emergence of the low-cost radiation detector comes at a time when Japan appears to be making a major shift in its energy policy.
As a resource-poor island nation, Japan has become more wary of relying on volatile global gas and coal markets. At the same time, massive new data centers and semiconductor factories are increasing the demand for stable, round-the-clock backbone power that solar and wind alone cannot reliably provide.
Japan also has a legally binding goal to reach net-zero emissions by 2050, a goal that would be difficult to achieve without nuclear power.
The government, under Prime Minister Sanae Takaichi, abandoned its previous commitment to reduce reliance on nuclear energy. Instead, the Seventh Energy Basic Plan, approved in early 2025, sets a goal for nuclear energy to provide about 20% of Japan’s electricity by 2040, up from about 9% in 2024.
This transformation took a practical step on January 21, 2026, when TEPCO began procedures to restart the Kashiwazaki-Kariwa plant, the largest nuclear power plant in the world. This was the first time since 2011 that TEPCO, the operator of the Fukushima plant, was allowed to restart a reactor.
However, public confidence in nuclear energy remains fragile due to past disasters and scandals. In this context, technologies that enhance transparency, preparedness, and field safety monitoring can help rebuild confidence.
Although the portable system developed by Hiroshima University is no substitute for large-scale monitoring infrastructures, its speed, low cost, and accessibility make it a widely available tool, and it indicates a growing realization that personnel-level preparedness tools may become more important as Japan’s cautious return to nuclear power.
