Gastrin-releasing peptide receptor (GRPR) is a member of the G protein-coupled receptor family of bombesin receptors, which is over-expressed in various types of cancer cells, including prostate cancer, breast cancer, colorectal cancer, pancreatic cancer, glioma, lung cancer, ovarian cancers, endometrial cancers, renal cell cancer and gastrointestinal stromal tumors. BBN(7-14), with the amino acid sequence of Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH2, has been extensively used for the development of molecular probes for the imaging of GRPR. On the other hand, the RGD moiety binds with integrin αvβ3 receptor, also plays an important role in the regulation of tumor growth, angiogenesis, local invasiveness, and metastatic potential in human breast cancer. To target both receptors, a heterodimeric peptide BBN-RGD was synthesized from bombesin(7-14) and c(RGDyK) through a glutamate linker and then labeled with 68Ga. An open-label whole-body PET/ CT study was designed to investigate the safety and dosimetry of 68Ga-NOTA-BBN-RGD and diagnostic performance of 68Ga-NOTA-BBN-RGD PET/CT in breast cancer patients.