Basic characteristics in dosimetry of the surface radioactive source

Three general rules of a radiation protection are the distance, time and shelter. The attenuation of radiation is based on inverse square law of the distance in theory, but this is a thing by a point source. Since it's necessary to treat as the surface radioactive source in the medical treatment for which many radioactive sources are used, and it influences the value of the leak dose distribution in a radiation irradiation room. When using several kinds of radioisotope, radiation exposure by radiation from which the energy is different in wide range shows. The purpose of this research is to make the basic characteristics necessary to a dose assessment of the surface radioactive source clear