In this paper, a digital signal processing system for image reconstruction of continuous wave diffusion optical tomography (CW-DOT) is proposed. Optical tomography systems employing near-infrared light can be used to detect oxygen concentration and impurities such as breast cancer in the human body. The proposed CW-DOT architecture is a truly appropriate system for further enhancing the possibility of miniaturization. The system is designed with the goal of high accuracy, low power and low cost for portable biomedical system on a chip (SoC) applications. Finally, the system has been verified on an SoC development platform, demonstrating fast and accurate reconstruction of two-dimensional (2D) DOT images.