Diffuse Optical Tomography (DOT) is a relatively novel, nonionizing and noninvasive technique for breast tumor imaging. Due to the diffusive nature of light propagation, the inverse problem is highly ill-posed. In this study, we propose the modified Beer-Lambert's law that reduces the number of unknown values to reduce the ill-posedness issue. An integrated mobile DOT system is proposed. The system comprises a front-end circuit and an integrated digital signal processor. The sources and the detectors are distributed hexagonal geometry for increasing the spatial resolution. The processor included the front-end controller, the iteration algorithm engine and wireless communication controller were implemented on FPGA. The functionalities of the proposed system were validated using a breast phantom. Extensive experimental results illustrated to show the performance of the proposed system. The depth of the tumor detected by the system is 20mm.