A method includes the following steps: positioning a patient at a first orientation relative to a radiation source, obtaining a measurement of the patient's breathing, and obtaining a measurement of the patient's cardiac function. The method includes, while the patient is positioned at the first orientation relative to the radiation source, and while obtaining the measurement of the patient's breathing phase, determining, from the measurement of the patient's breathing, a breathing phase of the patient and determining, from the measurement of the patient's cardiac function, a cardiac phase of the patient. The method includes gating the radiation source to expose the patient to radiation based on a determination that the breathing phase of the patient matches a predefined breathing phase and a determination that the cardiac phase of the patient matches a predefined window of the cardiac cycle.
