Quantification and Purity Analysis of Mass Separated 225Ra/225Ac for Medical Applications

Targeted alpha therapy, using 225Ac, is a promising approach in the fight against cancer. It delivers highly localized cytotoxic radiation to tumor cells while sparing healthy tissues. Despite its promise, the limited global production of 225Ac restricts its availability for large-scale clinical applications. Several techniques are being investigated to upscale the production. One of these techniques is the high-energy proton irradiation of Th/U targets to produce 225Ra, which beta-decays into 225Ac. As this process co-produces many other nuclei, ionization and mass separation are needed to reduce the presence of contaminants. However, due to the finite mass resolving power of the separator, neighboring masses can be present in the beam. This thesis focuses on quantifying a 225Ra sample produced at CERN MEDICIS. A detailed gamma-spectroscopy analysis quantified the activity of 225Ra at the end of collection. Using gamma- and alpha-spectroscopy the presence of 224Ra and 226Ra respectively were observed and quantified. For both 224Ra and 226Ra, the separation enhancement factors of 14(2)*10 and 16.7(19) showed a consistent reduction in the impurities compared to the amount produced in the target.  While 224/226Ra levels pose no risk to patients due to chemical separation during radiopharmaceutical preparation, the presence of 226Ra remains a challenge for waste management due to its 1600 year half-life, needing storage in long term waste facilities. These findings underscore the need for optimized production methods to minimize long-lived contaminants. To improve activity measurement accuracy, gamma-gamma coincidence techniques are promising but the resulting activity needs to be corrected for the angular distribution in the decay. Therefore, this thesis studies angular distributions in the 225Ac decay chain. For the transitions in 209Tl, the result agreed with theory. The 213Bi measurements suffered from low counting statistics, leading to large uncertainties on the angular distribution parameters. These results underscore the need for enhanced detection capabilities. The IS741 experiment conducted at CERN ISOLDE, as described in the third part of this thesis, is a setup with 12 High Purity Germanium detectors that allows for the angular distribution to be determined significantly more precise. Currently, data has been collected but data analysis is still ongoing.