Systems and methods directed to real-time treatment margin adaptation based on in-treatment imaging are provided. The system and method may utilize the potential of motion mitigation techniques such as couch tracking, DMLC, beam tracking, and the like to freeze tumor motion within the treatment aperture. A standard internal target volume (ITV) based margin plan and a minimum margin plan is created for the patient. The minimum margin plan assumes frozen intrafractional tumor motion. Depending on tumor location confidence in the motion mitigation technique, MLC leaf positions can be interpolated between the two plans to adjust margins during treatment delivery. If motion mitigation fails, the plan can be disabled resulting in the delivery of the current clinical standard of care. Dynamic aperture tracking may be employed with an electronic portal imaging device as the in-treatment imaging modality.
