Development of a dynamic optical tomographic breast imaging system with digital detection techniques

Breast cancer characteristics such as angiogenesis and hypoxia can be quantified by using optical tomography imaging to observe the hemodynamic response to an external stimulus. A digital near-infrared tomography system has been developed specifically for the purpose of dynamic breast imaging. It simultaneously acquires four frequency encoded wavelengths of light at 765, 808, 827, and 905nm in order to facilitate the functional imaging of oxy- and deoxy-hemoglobin, lipid concentration and water content. The system uses 32 source fibers to simultaneously illuminate both breasts. There are 128 detector fibers, 64 fibers for each breast, which deliver the detected light to silicon photo-detectors. The signal is conditioned by variable gain amplifiers and filters and is quantized by an analog to digital converter (ADC). The sampled signal is then passed on for processing using a Digital Signal Processor (DSP) prior to display on a host computer. The system can acquire 2.23 frames per second with a dynamic range of 236 dB.