Fluorescence-enhanced optical tomography with a radiative transfer-based model

Time-dependent measurements of light propagation have been demonstrated to provide more information compared to time- independent, or continuous wave (CW) measurements for image reconstruction, when employing absorption or fluorescence contrast. Time-dependent measurements made in the frequency domain have been experimentally made with good signal-to-noise ratio (SNR) in preclinical and clinical research at modulation frequencies of 100 MHz or less. However, measurements of higher modulation frequencies have potential to improve the reconstruction quality, if SNR can be conserved. In addition, the diffusion approximation (DA) has been demonstrated in both time dependent and independent measurements to be inaccurate in small tissue volumes as well as under conditions of high absorption and low scattering. In this paper, we proposed the third-order simplified spherical harmonics approximations (SP₃)-based reconstruction algorithm for fluorescence enhanced optical tomography (FEOT) made in the frequency domain for enhanced accuracy at high modulation frequencies. In this algorithm, fully parallel implementation significantly improves the reconstruction speed and makes the large-scale data-based reconstruction possible. With the Monte Carlo-based synthetic data on the digital mouse phantom, the reconstructed results show the advantages of the proposed algorithm compared to DA-based reconstruction method.