Design and testing of a near-infrared computed tomography device for breast tumor characterization

The design of a frequency-domain near-infrared scanning device is considered in order to determine how the source-detector geometry affects the resulting reconstruction of the tissue images. The measurements are processed by a finite element-based algorithm which reconstructs the interior image map of the absorption and scattering coefficients. This reconstruction is achieved by matching the light fluence measurements to calculated values based upon the assumption that light diffuses in tissue, and is predicted by the diffusion equation. An initial series of computer simulations have been used to evaluate the source-detector geometry, and predict how the measurement geometry affects the reconstruction accuracy and image quality. A physical device has been realized, using the optimal design, and is currently in a clinical trial to characterize the optical properties of breast tissues and tumors in vivo. The device uses 16 source and 16 detector locations alternating in a circular array, which can be attached to the breast tissue during a patient exam. Initial phantom and tissue studies indicate that quantitatively accurate images of the absorption coefficient can be obtained at multiple near infrared wavelengths.