Methods and apparatus for the planning and delivery of radiation treatments

A system for delivering radiation dose to a target area within a subject, the system comprising:

• a treatment radiation source for outputting a treatment radiation beam;
• a support for supporting the subject;
• a movement mechanism for moving the treatment radiation source relative to the subject along a trajectory;
• an imaging apparatus for capturing images;
• a controller configured, in accordance with a radiation delivery plan, to:
• cause the treatment radiation source to deliver the treatment radiation beam to the subject while causing the movement mechanism to effect relative movement between the treatment radiation source and the subject along the trajectory;
• and
• while causing the movement mechanism to effect relative movement between the treatment radiation source and the subject along the trajectory, cause the treatment radiation source to vary at least one of:
• an intensity of the treatment radiation beam by varying a radiation output rate of the treatment radiation source according to the radiation delivery plan over at least a portion of the trajectory and a shape of the radiation treatment beam over at least a portion of the trajectory;
• to thereby deliver dose to the subject according to the radiation delivery plan and capture images of the target area;
• wherein the imaging apparatus captures two-dimensional projection images of the target area at a plurality of locations along the trajectory.