Diffuse optical tomography using multi-directional sources and detectors

Abstract

Diffuse optical tomography (DOT) is an advanced imaging method used to visualize the internal state of biological tissues as 3D images. However, current continuous-wave DOT requires high-density probe arrays for measurement (less than 15-mm interval) to gather enough information for 3D image reconstruction, which makes the experiment time-consuming. In this paper, we propose a novel DOT measurement system using multi-directional light sources and multi-directional photodetectors instead of high-density probe arrays. We evaluated this system's multi-directional DOT through computer simulation and a phantom experiment. From the results, we achieved DOT with less than 5-mm localization error up to a 15-mm depth with low-density probe arrays (30-mm interval), indicating that the multi-directional measurement approach allows DOT without requiring high-density measurement. References and links1. M. Ferrari and V. Quaresima, "A brief review on the history of human functional near-infrared spectroscopy (fNIRS) development and fields of application," Neuroimage 63(2), 921-935 (2012).

The Comparison of Reconstruction Algorithms for Diffuse Optical Tomography

“…The iteration number determines the degree of the solution. It technique can be applied to the normal equations given by (10) A matrix is obtained using a Monte Carlo simulation of the light transport for the same source-detector distances as the optical probe. Obtaining the A is described in detail elsewhere [24].…”

Development of multi-directional functional near-infrared spectroscopy system for human neuroimaging studies

“…2(c)). Compared with our previous single-wavelength study [3], our new system had two sets of a VCSEL and a lens for spectroscopy and used a smaller prism. The tip of the prism was covered with 2-mm aperture ( Fig.…”

“…Figure 2(d) shows the detector probe. A lens and a photodetector, which is an array of four photodiodes, comprise the optical system for a multi-directional detector like in our previous study [3]. As well as an optical system, the detector probe had printed circuit boards for the I/V and A/D converters and the MCU.…”

“…where A is the sensitivity matrix [3] and x fMRI is the cortical absorption changes at 780 and 895 nm due to the hemodynamic changes. We calculated the sensitivity matrix with a Monte Carlo photon migration simulator called MCX (http://mcx.space/) with 10 9 photons.…”

“…To solve this problem, we previously proposed a multi-directional measurement system using multi-directional sources and detectors [3]. That system drastically increased the amount of measurement data without raising the number of probes by utilizing the multiple optical paths formed in multi-directional measurements [3,4] (Fig. 1(a)).…”