Work

Development and Dosimetric Characterization of an In Vitro Benchtop Americium 241 Alpha Irradiator Platform

Year: 2026

Type: article

Abstract: Purpose To expand preclinical efforts aimed at understanding the unique radiobiology of high linear energy transfer (LET) alpha particles and their implications for cancer therapy, robust, accessible, and high-throughput in vitro alpha irradiation platforms are needed. Such platforms must be extensively characterized and validated to ensure rigor and reproducibility. Here, we describe the construction and dosimetric characterization of a benchtop in vitro alpha irradiation platform using an Americium-241 ( 241 Am) source. Methods and Materials A square foil with embedded 241 Am was used as the alpha source (activity 3.3785 mCi). The source was secured in the roof of a custom housing incorporating a 3D-printed microcapillary array collimator to exclude large-angle alpha particles, thereby narrowing the energy spectrum, and improving homogeneity. A movable shelf accommodates cells grown on glass slides at variable distances from the source. Dosimetric characterization included direct measurement of dose homogeneity, source self-attenuation, energy spectra, absorbed dose, and dose rate. Results The 241 Am source, when used in conjunction with the microcapillary array, provided a spatially uniform and geometrically stable irradiation field. The mylar entrance window resulted in predictable shifting and broadening of the alpha particle energy spectra. Absorbed dose and dose-rate measurements (5.815 - 7.721 mGy/s) demonstrated feasibility of controlled in vitro alpha particle irradiation studies. Conclusions We established a turnkey, low-cost in vitro alpha irradiation platform suitable for high-throughput preclinical studies. The homogeneity, alpha particle energy spectra, absorbed dose and dose rate were characterized and validated through direct measurements. Given the approximately 432-year half-life of 241 Am, this platform will provide stable and reliable dose rates for decades, facilitating long-term radiobiological investigations.

Source: International Journal of Radiation Oncology*Biology*Physics

DOI: 10.1016/j.ijrobp.2026.05.058