Characterization of a custom-made 241Am alpha-source for radiobiological studies

Highlights: • Characterization of a compact ²⁴¹Am alpha-source. • Improvement of alpha particle energy spectrum with a 3D printed collimator. • Proven feasibility of a low-cost alpha-irradiation setup for in vitro assays. • Alpha particle RBE for 10% survival in PC-3 is 3.66. A compact in-house alpha particle source has been developed and fully characterized. The irradiation source is a large area, 25 cm², 5.4 MeV average energy ²⁴¹Am source, above which a Mylar dish containing a monolayer of target cells can be placed at defined positions. The source uniformity, flux, particle energy and dose rate were determined experimentally. The dose rate to the nucleus at the closest position was 1.57 Gy/min. Furthermore, a 3D printed collimator was tested and found to improve the uniformity of the energy spectra of particles reaching the target. For validation, prostate PC-3 cells were irradiated in our experimental setup with absorbed doses up to 2 Gy and for reference compared with cells irradiated with conventional X-rays with doses up to 8 Gy. The Relative Biological Effectiveness for alpha particles at 10% survival was 3.66$\pm$ 0.40 agreeing with previously published data. Data presented here show the feasibility of utilising a low-cost alpha-irradiation source for accurate in vitro assays to better understand the radiobiological effects of high LET alpha particles.