A radiation method which targets only the region surrounding the tumor in brachytherapy of breast cancer as Partial Breast Irradiation (PBI), was used to investigate the effect of two radiation sources ¹⁹²Ir and ⁶⁰Co on delivered doses for tumors near the surface of breast skin. To provide a clear image of position of the sources, contrast agent with different concentration were introduced. Contrast shows some significant reduction on dose for tumors near the skin than those farther. A dose modification factor (DMF) for different tumor depths were calculated.