Application
The authors of this paper sought to design an experiment to assess the RBE of alpha radiation from an external polonium-210 source using cultured porcine aortic endothelial cells as a surrogate for human tissues. As polonium-210 ingestion is associated with diets high in meat, especially caribou, this work seeks to provide insight into the risks associated with this activity. Further, this work sought to develop an improved method of RBE determination using an external radiation source; other common methods require adding radioactive salts to the cell culture medium itself. To perform these important experiments, a test apparatus was created using autoclaving resistant Master Bond EP3HTMED, a one-part epoxy that meets USP Class VI and ISO 10993-5 criteria for use as a biocompatible epoxy.
Key Parameters and Requirements
In the construction of their test assembly, the experimenters needed an adhesive to bond the glass support rings to the thin mylar sheets. Measuring 2.5 μm, the thin mylar film enabled transmission of the easily attenuated alpha particles emitted from the polonium-210 source to the test cells. In addition to forming a strong, water-tight bond between the glass and the mylar film, the adhesive must also possess the ability to resist autoclave sterilization as well as being biocompatible and non-cytotoxic. As the experiment primarily was assessing the continued viability of the porcine endothelial cells, it is critical that the test apparatus itself does not contribute to cellular harm. After assembly of the test apparatus and prior to introducing the cellular tissues, it is critical that the apparatus be sterilized. Autoclaving, exposure to high temperatures and pressures, is an effective and common means to sterilize and destroy any microbiological contaminants that may interfere with the scientific experiments. The experimenters constructed the apparatus shown in the below figure by bonding the glass support rings to the mylar film; curing of the epoxy was done at 150°C for 10 minutes. The dishes were then cut out from the excess mylar sheet, checked for water tightness, and were then autoclaved.
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1Thomas, P., Tracy, B., Ping, T, et al. International Journal of Radiation Biology. Relative biological effectiveness (RBE) of alpha radiation in cultured porcine aortic endothelial cells. Volume 83; 2007, pp. 171-179.
2Thomas, P., Tracy, B., Ping, T., et al. International Journal of Radiation Biology. Relative biological effectiveness (RBE) of polonium-210 alpha particles vs. x-rays on lethality in bovine endothelial cells. Volume 79; 2003, pp. 107-118