Diffuse Optical Tomography (DOT) is a novel medical image technology with non-invasive method in the recent years. However, it has not been popular in clinical practice. In this work, a custom signal processing engine for Continuous Wave (CW) DOT is proposed, for the forward and inverse problem in the calculating procedure. To achieve the goals of small hardware size, low power consumption, and popularity, the design applied the Very-large-scale integration (VLSI) concept. In addition, the design is also implemented onto System on a chip (SoC) with a front-end sensor control, wireless communication, and a user friendly interface as a prototype of a health care monitor system. Lastly, we demonstrate a static phantom experiment to verify the functionality of the whole proposed system.