Preliminary study on the visualization and evaluation of non-thermal plasma dose profiles using radiochromic film

Abstract Non-thermal plasma (NTP), also known as low-temperature plasma (LTP) or cold atmospheric plasma (CAP), has shown promise in cancer therapy and other biomedical applications, primarily through the generation of reactive oxygen and nitrogen species (RONS). However, the optimization of NTP-based treatments remains challenging because of the absence of standardized plasma dose units and practical methods for on-site dose profiling. In this study, we present a novel and simple approach for the visualization and measurement of NTP dose profiles using a currently available radiochromic film (Gafchromic EBT-XD) after removing a protective cover sheet. Clear radiochromic reactions were visible to the naked eye within seconds of helium-based NTP irradiation. The net optical density profiles of the RGB color components exhibited Gaussian distributions, with the red channel exhibiting the highest intensity. The X-ray equivalent doses derived from red channel optical densities reached approximately 40 Gy at the beam center for 10-s exposure at a distance of 8 mm or less and steeply declined at longer distances. The dose increased linearly with the irradiation time in the optimal dose range of the film (≤ 40 Gy). These findings demonstrate the effectiveness of this simple method for the rapid visualization of NTP beam and highlight its potential as a practical tool in biomedical applications including cancer treatment, enabling improved control and optimization of doses being delivered to patients. Graphical abstract