Systems and methods for energy modulated radiation therapy

A method performed by a medical device, the method comprising:

• adjusting an energy level of a particle beam within an accelerator to a first value with an energy switch communicatively coupled to the accelerator;
• providing the particle from the accelerator to a beam deflector, the beam deflector including a permanent magnet and an electromagnet;
• providing a permanent magnetic field by the permanent magnet;
• operating the electromagnet to provide a first electromagnetic field with a first electromagnetic field value based on the first value of the particle beam;
• adjusting the energy level of the particle beam within the accelerator to a second value with the energy switch;
• and
• operating the electromagnet to provide a second electromagnetic field with a second electromagnetic field value based on the second value of the energy level of the particle beam;
• wherein the first electromagnetic field with the first electromagnetic field value and the permanent magnetic field forms a first total magnetic field with a first total magnetic field value, and wherein the second electromagnetic field with the second electromagnetic field value and the permanent magnetic field forms a second total magnetic field with a second total magnetic field value.