Today by usage of the simulation of normal tissue and the process of material diffusion in body, the place of tumor can be predicted. By considering the tumor tissue, its growth can be evaluated. The fluid flow in the capillary, its effects on the adjacent tissue and the diffusion of molecules from capillary wall are considered in these kinds of simulation. Cancer cells due to the high rate of dividing cells, have a low level of oxygen. This lack of oxygen is called Hypoxia, so by using of different invasive and noninvasive manners, the amount of oxygen is measured in the body. The PET device indicates the oxygen distribution by use of special tracers in the several parts of body. In this essay by considering a real capillary network, the blood flow had been simulated, then by taking to the account of its effects on the tissue, oxygen pressure and the concentration of tracer had been simulated at the same time. At the end, the concentration of free and bind tracer is shown and its changes by the time is analyzed.