Evaluation of X-ray imaging properties of structured aluminum oxide matrices filled with different scintillator materials

The spatial resolution of currently commercially available X-ray scintillators is limited by their thickness. For instance a scintillator with a high thickness, yields a high efficiency but suffers from a decrease in spatial resolution due to (optical) light spreading in the scintillation layer. For thinner scintillators the opposing case is observed. The filling of structures like self-organized aluminum oxide (Alox), permits the fabrication of very thick and therefore highly efficient scintillator matrices without losing spatial resolution, due to the matrix' channel-like structures which act as light guides. We filled such structured Alox-matrices with different scintillator materials with two different methods. Non-hygroscopic scintillators like GOS or LSO can by filled into the matrices by a sedimentation process, but hygroscopic materials like CsI:Tl require a 'dry' process like melting. The focus of this paper is on the evaluation of the X-ray imaging properties of these filled matrices with respect to the achievable spatial resolution and signal-to-noise ratio. Especially for the CsI:Tl filled matrix we also studied the optical emission spectra, due to a loss of the dopant thallium during the melting process.