Fluorescent nuclear track detectors as a tool for ion-beam therapy research

Abstract

Originally designed for optical storage, fluorescent nuclear track detectors (FNTD) based on Al2O3:C,Mg single crystals contain aggregate F22+(2 Mg) color centers that show permanent radiochromic transformation when bombarded with ionizing radiation. Transformed centers produce high yield fluorescence at 750 nm when stimulated at 620 nm and a short (75±5 ns) lifetime. This enables non-destructive readout using confocal laser-scanning microscopes (CLSMs, Akselrod and Sykora, 2011). Since the intensity signal depends on the local energy deposition, 3D particle trajectories through the crystal can be assessed. Together with the excellent sensitivity Al2O3:C,Mg this enables the derivation of information on track location, direction, energy loss, etc. over the entire particle and energy range found in ion beam therapy. Effects such as projectile fragmentation and secondary electron trajectories can be studied in detail with diffraction-limited resolution (Greilich et al., 2013). Due to their biocompatibility, autoclavability and since post-irradiation chemical processing is not needed, FNTDs can show significant superiority to existing technologies such as plastic nuclear track detectors (PNTDs, e.g. CR-39).