A method of compensating for unexpected changes in the size, shape, and/or position of a patient in the delivery of radiation therapy. An image of a patient is used to prepare a treatment plan for the irradiation of a tumor or the like, shown in the image. A second image of a patient includes a visual representation of the tumor and sensitive structures wherein any combination of the size, shape, or position of the tumor or sensitive structures is different from any combination of the size, shape, or position of the visual representation of the tumor or sensitive structures in said first image. The radiation treatment is adjusted to more closely conform the treatment plan to the new size, shape, or position of the tumor as shown in said second image. This adjustment can occur before, during, or after the radiation delivery and can be used to define trade-offs that exist for the delivery. The trade-offs can be assessed and decisions made regarding which fluence adjustment strategy will be acceptable for treatment delivery.