Gadolinium-based MRI contrast agents are deemed safe to use in diagnostic exams. Their use would bring value to radiation oncology applications such as daily replanning on the MR-Linac. However, their stability and safe use in the presence of high-energy radiation remains unknown. We analyzed the chemical composition stability of two common MRI contrast agents that were irradiated to various doses using mass spectrometry. We found no detectable amounts of degradation compounds or conformational alterations as a result of irradiation. This is the first step towards demonstrating the safe use of gadolinium-based MRI contrast agents in radiation oncology applications.