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Proceedings Paper

Multichannel photon counting DOT system based on digital lock-in detection technique
Author(s): Tingting Wang; Huijuan Zhao; Zhichao Wang; Shaohua Hou; Feng Gao
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Paper Abstract

Relying on deeper penetration of light in the tissue, Diffuse Optical Tomography (DOT) achieves organ-level tomography diagnosis, which can provide information on anatomical and physiological features. DOT has been widely used in imaging of breast, neonatal cerebral oxygen status and blood oxygen kinetics observed by its non-invasive, security and other advantages. Continuous wave DOT image reconstruction algorithms need the measurement of the surface distribution of the output photon flow inspired by more than one driving source, which means that source coding is necessary. The most currently used source coding in DOT is time-division multiplexing (TDM) technology, which utilizes the optical switch to switch light into optical fiber of different locations. However, in case of large amounts of the source locations or using the multi-wavelength, the measurement time with TDM and the measurement interval between different locations within the same measurement period will therefore become too long to capture the dynamic changes in real-time. In this paper, a frequency division multiplexing source coding technology is developed, which uses light sources modulated by sine waves with different frequencies incident to the imaging chamber simultaneously. Signal corresponding to an individual source is obtained from the mixed output light using digital phase-locked detection technology at the detection end. A digital lock-in detection circuit for photon counting measurement system is implemented on a FPGA development platform. A dual-channel DOT photon counting experimental system is preliminary established, including the two continuous lasers, photon counting detectors, digital lock-in detection control circuit, and codes to control the hardware and display the results. A series of experimental measurements are taken to validate the feasibility of the system. This method developed in this paper greatly accelerates the DOT system measurement, and can also obtain the multiple measurements in different source-detector locations.

Paper Details

Date Published: 1 March 2011
PDF: 10 pages
Proc. SPIE 7896, Optical Tomography and Spectroscopy of Tissue IX, 789612 (1 March 2011); doi: 10.1117/12.871779
Show Author Affiliations
Tingting Wang, Tianjin Univ. (China)
Huijuan Zhao, Tianjin Univ. (China)
Zhichao Wang, Tianjin Univ. (China)
Shaohua Hou, Tianjin Univ. (China)
Feng Gao, Tianjin Univ. (China)

Published in SPIE Proceedings Vol. 7896:
Optical Tomography and Spectroscopy of Tissue IX
Bruce Jason Tromberg; Arjun G. Yodh; Mamoru Tamura; Eva Marie Sevick-Muraca; Robert R. Alfano, Editor(s)

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