Cost-effective on-site dose assessment by a combination of radiochromic film and smartphone

To minimize health injuries in mass-casualty nuclear events, personal-level preparedness, including a simple, universal, and cost-effective dosimetry tool, is crucial. In this study, we propose an inexpensive dosimetry system using a radiochromic film, which can immediately detect high-dose radiation exposure by the naked eye, and a portable scanner coupled with a smartphone as a practical tool for radiological emergency preparedness. Small pieces of Gafchromic EBT4 films were irradiated with X-rays (160 kVp, 6.3 mA) at 2.5, 5.0, and 10 Gy (for water) and scanned on an LED light table of a commercially available portable scanner (PictoScanner ApS, Denmark) using four different smartphones: Samsung Galaxy A23 5G SC-56C, Samsung Galaxy Note8, iPhone Xs Max, and iPhone 13 Pro Max. The dose responses of the 8-bit color intensities of the red, green, and blue (RGB) and cyan, magenta, yellow, and black (CMYK) channels were analyzed. Smartphone cameras of the same company exhibited similar response characteristics. Among the seven color channels, the intensity of the cyan channel was the highest and increased with dose. However, the results at 2.5 Gy showed large discrepancies, which could be attributed to the low color intensities. According to the findings, this inexpensive portable dosimetry tool is expected to be effectively applied for on-site emergency dosimetry in relatively high-dose (≥5 Gy) situations. Although this approach requires preparatory actions, such as the pre-distribution of film pieces and the provision of portable scanners, these are practically achievable at a reasonable cost. Further efforts are required to widen the applicable dose range and to develop practical calibration procedures. • A novel portable dosimetry system using a smartphone and radiochromic film was tested. • Four smartphones successfully detected dose-dependent color changes in the EBT4 film. • Cyan color intensity was considered universally useful to measure a high dose ≥5 Gy.