Current Projects:

CMOS Image Sensors for Near-Infrared Frequency-Domain Optical Mammography Systems

Biomedical optical imaging technology is emerging as a promising alternative for early breast cancer detection, compared to x-ray mammography. In addition to being a safe, noninvasive method for screening, optical imaging methods offer potentially low-cost and relatively portable instrumentation for use in primary care situations. Recent research has shown that frequency-domain spectroscopy, where the light source intensity is sinusoidally modulated, can achieve richer information content improving image resolution and tumor detectability. A typical frequency-domain optical mammography system is shown in Fig.1. Four fiber-coupled laser diodes(690nm to 865nm) are sinusoidally modulated around 70MHz. The transmitted light is received on the opposite side of the tissue by a photomultiplier tube(PMT) producing an electrical signal for further signal processing. In addition to measuring the optical signal attenuation, this frequency domain approach measures the phase shift to determine the mean path length of photons as a second parameter to generate a high resolution oxygenation index image of the tissue. Due to the diffusive nature of breast tissue, experimental results have shown that multiple detector in a planar configuration can enhance spatial information and depth discrimination.

Reference:

[1] S. Fantini, E. L. Heffer, V. E. Pera, A. Sassaroli, and N. Liu, “Spatial and spectral information in optical mammography.” Technol Cancer Res Treat, vol. 4, no. 5, pp. 471–482, Oct 2005.

[2] Fantini, E. L. Heffer, M. A. Franceschini, L. GĂ˝utz, A. Heinig, S. Heywang-KĂ˝ubrunner, O. SchĂijtz, and H. Siebold, “Optical mammography with intensity-modulated light.” Proceedings of Inter-Institute Workshop on In Vivo Optical Imaging at the NIH, 2000.

[3] N. Liu, A. Sassaroli, M. A. Zucker, and S. Fantini, “Three-element phased-array approach to diffuse optical imaging based on postprocessing of continuous-wave data.” Opt Lett, vol. 30, no. 3, pp. 281–283, Feb 2005.

 

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