Systems for delivering radiation dose to a target area within a subject comprise: a radiation source for outputting a radiation beam； a support for supporting the subject； a movement mechanism for moving the radiation source relative to the subject along a trajectory； and a controller configured to cause, according to a radiation delivery plan: the radiation source to deliver the radiation beam to the subject while causing the movement mechanism to effect relative movement between the radiation source and the subject along the trajectory； and the radiation source to vary an intensity of the radiation beam by varying a radiation output rate of the radiation source according to the radiation delivery plan over at least a portion of the trajectory while causing the movement mechanism to effect relative movement between the radiation source and the subject, to thereby deliver dose to the subject according to the radiation delivery plan.
