25 March 2013 Numerical and experimental studies of x-ray luminescence optical tomography for small animal imaging
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Abstract
X-ray luminescence optical tomography (XLOT) is an emerging hybrid imaging modality in which x-ray excitable particles (phosphor particles) emit optical photons when stimulated with a collimated x-ray beam. XLOT combines the high sensitivity of optical imaging with the high spatial resolution of x-ray imaging. For XLOT reconstruction, we compared two reconstruction algorithms, conventional filtered backprojection (FBP) and a new algorithm, x-ray luminescence optical tomography with excitation priors (XLOT-EP), in which photon propagation is modeled with the diffusion equation and the x-ray beam positions are used as reconstruction priors. Numerical simulations based on dose calculations are used to validate the proposed XLOT imaging system and the reconstruction algorithms. Simulation results show that XLOT can better detect inclusions of particles than x-ray computed tomography (CT) alone. Nanoparticle concentrations reconstructed with XLOT-EP are much less dependent on target depths than those obtained with FBP. Measurements at just two orthogonal projections are sufficient for the XLOT-EP to reconstruct an XLOT image for simple source distributions. The heterogeneity of x-ray dose distribution is included in the XLOT-EP reconstruction and improves the reconstruction accuracy, suggesting that there is a need to calculate the x-ray dose distribution for experimental XLOT imaging. We have built a prototype XLOT imaging system, in which a collimated x-ray bean is used to scan the samples and an electron multiplying charge couple device (EMCCD) is used to collect the optical photons emitted by the x-ray excitable particles. Phantom experiments have been performed to validate the XLOT system and the proposed reconstruction algorithms.
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Changqing Li, Arnulfo Martínez Dávalos, Simon R. Cherry, "Numerical and experimental studies of x-ray luminescence optical tomography for small animal imaging", Proc. SPIE 8578, Optical Tomography and Spectroscopy of Tissue X, 85781B (25 March 2013); doi: 10.1117/12.2004770; https://doi.org/10.1117/12.2004770
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