• electron flash irradiation
• oxygen depletion
• phosphorensce-quenching method

This thesis focused on the development and optimization of an experimental system for measuring the oxygen concentration in water using the characteristic quenching time of a phosphorescent probe. The final goal is to employ this probe to monitor the changes in oxygen levels induced by FLASH and conventional low-energy e-beams in healthy and tumor tissues, to contribute to understanding the radiobiological mechanisms involved in the FLASH effect.
The work was divided into different phases. In a first step, preliminary measurements were conducted at CPFR in Pisa. The goals were to assess the capability to detect the phosphorescence when the probe in water solution was excited by the Cherenkov radiation and to discriminate variations in the oxygenation level of the solution. The experimental setup was then optimized with laboratory measurements, using an LED instead of Cherenkov radiation to excite the probe. Various factors that could potentially influence the decay constant of the phosphorescent emission were analyzed, and a spectrometer was also employed. The results of this thesis showed that a simple photodetector can measure the phosphorescence-quenching time in a water solution, and thus potentially provide information on the variations of oxygen level during FLASH irradiations.