Time-domain diffuse optical tomography using recursive direct method of calculating Jacobian at selected temporal points

Abstract

An algorithm for time-domain diffuse optical tomography based on the resolution of the timedomain diffusion equation using the finite element method has been developed. An efficient direct method including a recursive approach has been used to obtain the light fluence derivatives with respect to tissue optical properties at precise selected points on the temporal profile resulting in a considerable savings in computation time and memory. The algorithm reconstructs the tissue optical properties in a permissible region or a region-of-interest and the input data for reconstruction comprises selections of points on the temporal curve of the measured pulse. The optical properties have been reconstructed by solving an iterative normalized minimization problem. The algorithm has been applied to a three-dimensional simplified model of a new born baby head and to a threedimensional model of the mouse (MOBY) for a small animal model. The computation speed and memory usage of the algorithm have been compared with that of other techniques based on continuous wave and frequency domain representations. The effects of using different sizes of time steps and number of time steps on the reconstruction accuracy and the computation time have been reported.

Time-Resolved Diffuse Optical Spectroscopy and Imaging Using Solid-State Detectors: Characteristics, Present Status, and Research Challenges

“…However, for each slice the inverse problem must be solved in serial. To date, a fast forward problem model that uses a GPU is available, and the approach of using only a few points was validated in simulation for transmittance measurements only [ 69 , 86 , 87 ]. Therefore, the integration of these two approaches would lead to the reconstruction of images at a much faster speed (within tens of seconds).…”

“…To use these iterative processes with all the data points of the DToF are computationally expensive. Therefore, some accelerated FEM approaches were recently demonstrated by analyzing a few critical points from the DToF curves for transmittance geometry measurements (only for simulating data), instead of using all points on the histogram that are not needed, and significantly increases the processing time [ 86 , 87 ].…”

Time-Domain Near-Infrared Spectroscopy and Imaging: A Review

“…For saving computation time and memory, Naser and Deen [180] developed a recursive equation to calculate the sensitivity (Jacobian) at a specific time step from the calculated fluence rates at all the previous time steps.…”

“…2019, 9, x FOR PEER REVIEW 32 of 53 and the larger the value of n, the deeper the sensitivities extended. Also, the feasibility of short SD distances of 10 mm and 15 mm was studied for application of the null SD distance technique using an experimental setup employing a fast-gated SPAD [134,180]. For saving computation time and memory, Naser and Deen [181] developed a recursive equation to calculate the sensitivity (Jacobian) at a specific time step from the calculated fluence rates at all the previous time steps.…”

Characterization of a Time-Resolved Diffuse Optical Spectroscopy Prototype Using Low-Cost, Compact Single Photon Avalanche Detectors for Tissue Optics Applications

“…These requirements limit the use of TR-DOS systems for potential applications such as nondestructive optical characterization of pharmaceuticals, food, wood, and for clinical applications such as muscle monitoring, functional brain imaging and optical mammography [ 1 , 2 ]. Therefore, significant efforts are being made to simplify the complexity of TR-DOS systems to develop and utilize affordable instruments and to analyze the experimental data using efficient computational methods [ 1 , 2 , 16 , 17 ] As a result, it is expected that compact, low cost and portable multichannel TR-DOS systems will be available in the near future [ 1 , 2 , 18 ].…”