Hiroshima, Japan – A team of researchers has developed a way to turn smartphone cameras into portable radiation detectors, a breakthrough that could dramatically improve response times during nuclear accidents or radiological emergencies. The new system, detailed in the review Radiation Measurements, offers a low-cost, rapidly deployable alternative to expensive and often cumbersome traditional methods.
Measuring Radiation Exposure: A Critical Challenge
Accurate dose estimation is paramount during a nuclear accident or radiological event. According to the International Commission on Radiological Protection (ICRP), an acute exposure exceeding 3 or 4 grays carries a 50% probability of death within 60 days without treatment. However, dangerous levels of radiation exposure can occur without immediately visible symptoms, making timely intervention crucial.
Individual dosimetry – quickly assessing the radiation dose received by a person – is a vital component of patient care. Current methods often rely on costly equipment, laboratory scanners, or optical reading systems ill-suited for emergency situations. This prompted researchers at Hiroshima University to seek a more accessible solution.
How a Smartphone Reads Radiation Through Color
The core of the system utilizes Gafchromic EBT4 radiochromic film, commonly used in radiotherapy to validate irradiation beams. This film uniquely changes color when exposed to ionizing rays. To decipher this color change, the Japanese team engineered a lightweight, foldable device called the PictoScanner, featuring uniform LED lighting and a smartphone mount.
When the exposed film is placed under the scanner, the smartphone camera captures a high-resolution image. Analysis is performed using a mobile application or open-source software like ImageJ.JS, which extracts colorimetric values (RGB or CMYK) from the image, with a particular focus on red and cyan channels. Tests on models including the iPhone 13 Pro Max, iPhone XS Max, Galaxy A23, and Note8 revealed a linear response in the cyan channel up to 10 Gy.
New Atlas reports that this seemingly simple method is grounded in rigorous calibration. Researchers capture images in RAW format, without compression, and analyze them using standard conversion functions, selecting a central image area to minimize edge effects and lighting artifacts. This process enables reliable dose estimation within a range relevant to emergency response.
Limitations and Future Development
The approach developed by Hassna Bantan and Hiroshi Yasuda allows for reliable detection above 5 Gy, making it suitable for situations involving potentially lethal doses. However, it currently struggles to identify lower-level exposures that can still cause long-term health effects. Researchers aim to improve sensitivity by combining more responsive films with advanced smartphone sensors.
The study also highlighted variations between smartphone models. While the Galaxy A23 and iPhone XS demonstrated good reproducibility, accuracy depends on the sensor, manual settings (white balance, ISO, focus), and lighting conditions. Standardization of imaging protocols and the development of universal software tools are needed to ensure widespread reliability.
The accessibility of this solution is also contingent on logistical planning. While the film costs less than 2 euros and the scanner remains under 70 euros, widespread implementation requires proactive distribution of kits, user training, and integration into disaster response plans. The potential is significant, but requires overcoming these final hurdles.
