Abstract: A method performed by a medical device, includes: providing a permanent magnetic field by a permanent magnet; operating an electromagnet to provide a first electromagnetic field with a first electromagnetic field value; and operating the electromagnet to provide a second electromagnetic field with a second electromagnetic field value; wherein the first electromagnetic field and the permanent magnetic field forms a first total magnetic field with a first total magnetic field value, and wherein the second electromagnetic field and the permanent magnetic field forms a second total magnetic field with a second total magnetic field value; wherein the first total magnetic is formed when an electric field in an accelerator or an energy level of a particle beam has a first value, and wherein the second total magnetic field is formed when the electric field in the accelerator or the energy level of the particle beam has a second value.

Abstract: A method performed by a medical device, includes: providing a permanent magnetic field by a permanent magnet; operating an electromagnet to provide a first electromagnetic field with a first electromagnetic field value; and operating the electromagnet to provide a second electromagnetic field with a second electromagnetic field value; wherein the first electromagnetic field and the permanent magnetic field forms a first total magnetic field with a first total magnetic field value, and wherein the second electromagnetic field and the permanent magnetic field forms a second total magnetic field with a second total magnetic field value; wherein the first total magnetic is formed when an electric field in an accelerator or an energy level of a particle beam has a first value, and wherein the second total magnetic field is formed when the electric field in the accelerator or the energy level of the particle beam has a second value.

Abstract: A medical apparatus includes: a beam deflector having an electromagnet configured to provide a first magnetic field for deflecting a particle beam; and a current control configured to adjust a current of the electromagnet in correspondence with an energy level associated with an accelerator. A treatment planning method includes: defining control points in a treatment plan; setting up energy switching in one or more of the control points; and performing treatment optimization on the treatment plan based at least in part on the energy switching that is set up in the one or more of the control points. The medical apparatus also includes an energy adjuster configured to adjust the treatment energy so that the treatment energy has a first energy level when the beam output is at the first gantry angle, and a second energy level when the beam output is at the first gantry angle.

Abstract: A medical apparatus includes: a beam deflector having an electromagnet configured to provide a first magnetic field for deflecting a particle beam; and a current control configured to adjust a current of the electromagnet in correspondence with an energy level associated with an accelerator. A treatment planning method includes: defining control points in a treatment plan; setting up energy switching in one or more of the control points; and performing treatment optimization on the treatment plan based at least in part on the energy switching that is set up in the one or more of the control points. The medical apparatus also includes an energy adjuster configured to adjust the treatment energy so that the treatment energy has a first energy level when the beam output is at the first gantry angle, and a second energy level when the beam output is at the first gantry angle.

Abstract: An in-line MRI-linac apparatus is provided that includes an MRI magnet of an MRI scanner, where the MRI magnet generates a magnetic field, where the magnetic field has a quasi-uniform fringe field, where the fringe field is proximal to an axis of symmetry of the MRI magnet, and a magnetically unshielded dynamically moveable linac that includes a treatment beam that is aligned with field lines of the fringe field in a quasi axial symmetric configuration, where a position of the linac in the fringe field continuously adapts according to a target position to enable continuous dose delivery to the target.

Abstract: A method of configuring an electron gun for generating and injecting an electron beam into a linac accelerating waveguide operating in magnetic fringe fields of an MRI scanner in the absence of a magnetic shield is provided using an appropriately programmed computer to determining an anode drift tube diameter at an injection point of a linac according to a magnetic field value from an MRI scanner and to a predetermined current density, where the magnetic field has an isocenter, determining a transverse diameter of a Type M cathode in an electron gun, according to the anode drift tube diameter and the current density, and minimizing an emittance value in an electron beam of the electron gun at an entry point of the anode drift tube by optimizing the distance between the cathode and the anode, where the electron beam is along an axis of symmetry of the magnetic field.

Abstract: An in-line MRI-linac apparatus is provided that includes an MRI magnet of an MRI scanner, where the MRI magnetic includes a magnetic field, where the magnetic field has a quasi-uniform fringe field, where the fringe field is proximal to an axis of symmetry of the MRI magnet, and a magnetically unshielded dynamically moveable linac that includes a treatment beam that is aligned with field lines of the fringe field in a quasi axial symmetric configuration, where a position of the linac in the fringe field continuously adapts according to a target position to enable continuous dose delivery to the target.