We have presented a strategy for incorporating low-molecular-weight Gd(III) chelate for dual non-invasive MR contrast agent and NCT, without the necessity of loading individual contrast therapeutic drugs, which is usually required in theranostics. The Gd-DO3A-BTA injected and neutron irradiated group, the tumor growth was significantly suppressed. This information could provide a basis for the prospect of obtaining a synergistic or cumulative action of chemotherapy (ChT) and Gd-NCT. We examined the neutron capture irradiation of MDA-MB-231 mice in the presence of Gd-DO3A-BTA. The results indicate that Gd-DO3A-BTA is suitable neutron capture agent for Gd-NCT.