Author: Md Mainul Abrar, Harsh Arya, Yujie Chi, Yijing Liu, Joshua Rajan, Pan Zui 👨🔬
Affiliation: University of Texas at Arlington, The University of Texas at Arlington, Department of Physics, University of Texas at Arlington 🌍
Purpose: Understanding the biological effects of alpha radiation at varying dose rates and energies is essential for advancing therapeutic strategies. This study demonstrates the capabilities of an in-house alpha irradiation platform for in-vitro biological study, with versatile radiation control.
Methods: We developed an in-house alpha irradiation platform featuring an Am-241 source mounted on a linear manipulator that allows adjustment of the source-sample distance to vary the dose rate. The system includes a vacuum-based delivery setup maintained at 3.5E-3 hPa, separated by a Si3N4 exit window from air. Post it, a Mylar-film-bottomed cell dish is positioned on a 2D motion stage. The system's beam quality was tested under three configurations: 1) 1 mm air gap + 2.5 μm Mylar film, 2) 1 mm air gap + 7.5 μm Mylar film, and 3) 2 cm air gap + 7.5 μm Mylar film, with a 13-inch source-window distance and a 100 nm window thickness. The biological effects of setup 3) were tested by irradiating KYSE150 cells for 90 minutes. Cell viability was assessed 24 hours later using Calcein AM and ethidium homodimer-1 fluorescence, while γH2AX immunostaining and confocal microscopy revealed DNA double-strand breaks.
Results: For the three radiation conditions, the measured mean alpha energy was 4.13, 3.69, and 0.31 MeV with CR-39 based detection. They are consistent with the computed energy of 4.15±0.01, 3.44±0.02, and 0.28±0.05 MeV, respectively. Under condition 3), the alpha counts reaching the cell sample was measured as 3.1mm-2 s-1 with estimated total dose of 0.12 Gy in a 5 μm cell layer. Irradiated samples showed significantly increased cell death and pronounced γH2AX staining confined to the irradiated region, absent in other areas or controls. The γH2AX z-stack matched the simulated alpha range distribution in cells.
Conclusion: The energy control of the alpha irradiation platform has been successfully validated.