Cold atmospheric pressure plasma dose measurements: focus on cancer research

Cold atmospheric pressure plasmas (CAP) have emerged as significant tools in cancer research and in other biological areas over the past decades, leveraging unique properties derived from plasma physics. These plasmas, characterized by their non-thermal nature and operation at atmospheric pressure, provide a novel approach to studying and potentially treating cancer due to their ability to generate reactive species and influence cellular processes. Despite their widespread use, precise CAP dose measurements- a critical parameter for understanding their interaction with biological systems-are still under active investigations. In this study, we conduct experimental studies on Alanine pellets and powder as dosimeters, exposed to CAP for varying durations, followed by analysis using electron paramagnetic resonance (EPR) spectroscopy. This technique, rooted in plasma-induced radical formation, enables us to quantify the alanine-EPR radical yield induced by CAP and to express it on a Co-60-calibrated operational scale. For calibration, the Alanine pellets, were subjected to known doses of ionizing radiation. By applying a numerical fitting procedure to the resulting EPR data, we constructed a Co-60 dose–response calibration curve and used it to estimate the CAP-induced alanine-EPR equivalent response in pellets and powder. Obtained results suggest that the Alanine powder could be a better choice than pellet for CAP dosimetric studies. This work provides an operational CAP exposure metric based on alanine-EPR radical yield expressed on a Co-60-calibrated scale, offering a reproducible, device-specific indicator useful for comparing exposure conditions within the same CAP system. Limitations regarding physical dose interpretation are discussed.