Effect of Shot Noise on Simultaneous Sensing in Frequency Division Multiplexed Diffuse Optical Tomographic Imaging Process.

Hansol Jang,Chang-Seok Kim,Gukbin Lim,Gultekin Gulsen,Jaedu Cho,Keum-Shik Hong

doi:10.3390/s17122752

Abstract

Diffuse optical tomography (DOT) has been studied for use in the detection of breast cancer, cerebral oxygenation, and cognitive brain signals. As optical imaging studies have increased significantly, acquiring imaging data in real time has become increasingly important. We have developed frequency-division multiplexing (FDM) DOT systems to analyze their performance with respect to acquisition time and imaging quality, in comparison with the conventional time-division multiplexing (TDM) DOT. A large tomographic area of a cylindrical phantom 60 mm in diameter could be successfully reconstructed using both TDM DOT and FDM DOT systems. In our experiment with 6 source-detector (S-D) pairs, the TDM DOT and FDM DOT systems required 6.18 and 1 s, respectively, to obtain a single tomographic data set. While the absorption coefficient of the reconstruction image was underestimated in the case of the FDM DOT, we experimentally confirmed that the abnormal region can be clearly distinguished from the background phantom using both methods.

Highlights

Diffuse optical tomography (DOT) using near-infrared (NIR) light is a promising medical diagnostic imaging technique because of its high imaging contrast performance in distinguishing tumors from normal tissue [1,2]
In time-division multiplexing (TDM) DOT, the total operation time obtained for a single data set can be expressed as n(TDAQ + TSW ), where n is the number of light sources, TDAQ is the data acquisition time for each source channel, and TSW is the channel switching time of the optical switch
We developed frequency-division multiplexing (FDM) DOT systems based on continuous wave (CW)-DOT and compared their performances with the TDM DOT system in terms of temporal resolution and image quality

Summary

Introduction

Diffuse optical tomography (DOT) using near-infrared (NIR) light is a promising medical diagnostic imaging technique because of its high imaging contrast performance in distinguishing tumors from normal tissue [1,2]. A tomographic reconstruction algorithm based on the photon diffusion model allows quantitative depth-resolved information in thick tissue. Owing to these capabilities, applications of DOT include quantitative functional cerebral studies [4,6,7], disease diagnosis [5], and neonatal hemorrhage detection [2,5]. Depending on the number of source channels, the TDM method may require a long time to measure a single tomographic data set, which causes a reduction in temporal resolution [8]. TDM DOT is not appropriate for applications which require high temporal resolution, such as the monitoring of blood flow, changes oxygen saturation, and response of vasoactive agents [9].

Methods

Results

Conclusion