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\bibitem{Nguyen_etal2011} Nguyen, C. V., Gillam, J. E., Brown, J. M. C., Martin, D. V., Nikulin, D. A., \& Dimmock, M. R. (2011). Towards Optimal Collimator Design for the PEDRO Hybrid Imaging System. \textit{IEEE Trans. Nucl. Sci.}, \textit{58}(3), 639--650.

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