The therapeutic effects and application of radiotherapy are restricted to some extent due to low radiosensitivity of tumor tissues and adverse effects by excess dosage. Current radiosensitizers are confronted with problems in clinical translation because of complicated manufacture technique and high cost. In this research, we have synthesized a radiosensitizer with advantages in low cost and mass production, which could be applied to CT imaging and enhanced radiotherapy in breast cancer, namely Bi-DTPA. It not only enhanced tumor CT imaging which resulted in better therapeutic accuracy, but also realized radiotherapy sensitization by producing massive ROS and inhibit tumor proliferation, providing a sound perspective in the clinical translation of the radiosensitizer.