title: Design and implementation of a multifrequency near-infrared diffuse optical tomography system.
abstract: The design and implementation of a multifrequency and multispectral diffuse optical tomography system is described. Four wavelengths are utilized: 665, 785, 808, and 830 nm. The system is based on a network analyzer, which provides rf modulation signals for the laser diodes, as well as measures the amplitude and the phase of the detected signals. Six different modulation frequencies ranging from 110 to 280 MHz are used. The details of instrumentation, calibration, data acquisition, and performance of the system are given. A finite element algorithm is used to solve the diffusion equation, and an inverse solver based on this forward solver is implemented to calculate the absorption and scattering maps from the acquired data. Data acquisition for one wavelength is completed in less than 2.5 min for a single modulation frequency. The measurement repeatability is 0.5% in ac intensity and 0.2 deg in phase. The performance of the system is evaluated with phantom studies. A multifrequency reconstruction algorithm is used, in which a single absorption and scattering image pair is obtained using the whole dataset obtained at different modulation frequencies. It is shown that the multifrequency reconstruction approach provides superior image quality compared to the single frequency counterpart.
authors.affiliation: University of California, Tu and Yuen Center for Functional Onco-Imaging, Irvine, California 92697, USA. ggulsen@uci.edu
authors.forename: Gultekin
authors.initials: G
authors.lastname: Gulsen
authors.forename: Bin
authors.initials: B
authors.lastname: Xiong
authors.forename: Ozlem
authors.initials: O
authors.lastname: Birgul
authors.forename: Orhan
authors.initials: O
authors.lastname: Nalcioglu
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared / Q000295:instrumentation* / Q000379:methods; D041622:Tomography, Optical / Q000295:instrumentation* / Q000379:methods