Abstract: A radiation therapy treatment method comprises imaging a subject and simulating four-dimensional aspects of radiotherapy. A treatment plan based on the simulation is generated to permit real-time, three-dimensional dose reconstruction at the time of treatment. The simulation and treatment plan are used during treatment fractions to achieve real-time image guidance.

Abstract: A radiation therapy System comprises a magnetic resonance imaging (MRI) apparatus and a linear accelerator capable of generating a beam of radiation. The linear accelerator is immersed in and oriented with respect to the MRI magnetic field to expose the linear accelerator to magnetic force that directs particles therein along a central axis thereof.

Abstract: Disclosed herein is a magnet assembly that includes at least two magnets arranged in a fixed spaced relationship with one another thereby to define a space between the magnets that encompasses an imaging volume. Each of the magnets produces a variety of magnetic field strengths across inward-facing surfaces thereof that, in combination, produce an acceptably homogeneous magnetic field in the imaging volume. Also disclosed is a method of defining a magnetic field for an imaging volume. The method comprises generating an initial model of a magnet assembly; estimating a magnetic field for the imaging volume based on the model; calculating deviation between the estimated magnetic field and a target magnetic field for the imaging volume; and updating the model to reduce the deviation by modifying the magnet assembly to produce a variety of magnetic field strengths that, in combination, produce substantially the target magnetic field in the imaging volume.

Abstract: A radiation therapy treatment method comprises imaging a subject and simulating four-dimensional aspects of radiotherapy. A treatment plan based on the simulation is generated to permit real-time, three-dimensional dose reconstruction at the time of treatment. The simulation and treatment plan are used during treatment fractions to achieve real-time image guidance.

Abstract: A radiation therapy system comprises a radiation source generating a beam of radiation and a magnetic resonance imaging apparatus. An interface acts between the radiation source and the MRI apparatus that permits irradiation to be performed simultaneously with imaging. The MRI apparatus and radiation source are coupled such that the system can be used in a rotation mode whereby the radiation source can irradiate a subject from basically any angle without reducing MRI image quality.