Non-achromatic compact gantry

A method for performing radiation therapy, the method comprising:

• receiving a particle beam emitted from a cyclotron;
• bending the beam by a first degree amount using a first dipole magnet;
• conditioning the beam asymmetrically to produce an asymmetric beam, wherein the conditioning comprises introducing an amount of asymmetry into the particle beam that based on a dispersion function of a second dipole magnet disposed at the last bend of a beamline;
• and
• bending the asymmetric beam by a second degree amount using the second dipole magnet, wherein the second dipole magnet disperses the asymmetric beam according to the dispersion function to account for the amount of asymmetry and produce a round beam cross-section at a treatment iscoenter.

A compact radiation therapy system, comprising:

• a cyclotron operable to emit a beam that is compact;
• a gantry coupled to the cyclotron and comprising:
• a first dipole magnet operable to bend the beam received from the cyclotron by a first degree amount;
• a second dipole magnet disposed at the last bend of a beamline;
• a degrader configured to reduce an energy of the beam;
• and
• one or more quadrupole magnets disposed in the beamline between the at least one first dipole magnet and the second dipole magnet, and configured to condition the beam to produce an asymmetric beam having an amount of asymmetry based on a dispersion function of the second dipole magnet;
• wherein the second dipole magnet is operable to receive the asymmetric beam and bend the asymmetric beam by a second degree amount, and wherein the second dipole magnet disperses the asymmetric beam according to the dispersion function to account for the amount of asymmetry and produce a round beam cross-section at a point of interest.