A particle therapy system for irradiating a target of a subject with a charged particle beam, said particle therapy system comprising: - a particle accelerator for generating the charged particle beam, - a beam delivery device for delivering the charged particle beam to the target, - a beam transport system for transporting the charged particle beam from the particle accelerator to the beam delivery device, - a supporting device for supporting the subject, the beam delivery device being rotatable around the target and with respect to the supporting device and/or the supporting device being rotatable with respect to the beam delivery device, so as to be able to deliver the charged particle beam to the target according to a plurality of irradiation angles (α), - a controller configured to make the beam delivery device rotate at a beam-on speed around the target and with respect to the supporting device and/or to make the supporting device rotate at a beam-on speed with respect to the beam delivery device and to meanwhile irradiate the target with the charged particle beam, the controller is configured to make the beam delivery device rotate around the target at at least two different and non-zero beam-on speeds with respect to the supporting device, a first beam-on speed corresponding to a first irradiation angle (α1) and a second beam-on speed corresponding to a second irradiation angle (α2) among the plurality of irradiation angles (α), and/or the controller is configured to make the supporting device rotate at at least two different and non-zero beam-on speeds with respect to the beam delivery device, a third beam-on speed corresponding to the first irradiation angle (α1) and a fourth beam-on speed corresponding to the second irradiation angle (α2) among the plurality of irradiation angles (α), the controller is further configured to make the beam delivery device rotate at a beam-off speed with respect to the supporting device or vice-versa and meanwhile to stop irradiating the target with the charged particle beam, characterized in that the charged particle beam is a beam of ions, in that the controller is further configured to make the beam delivery device rotate at at least two different and non-zero beam-off speeds with respect to the supporting device or vice-versa, a first beam-off speed corresponding to the first irradiation angle (α1) and a second beam-off speed corresponding to the second irradiation angle (α2) among the plurality of irradiation angles (α), and in that the controller is further configured to change an energy of the particle beam to be delivered to the target while the beam delivery device rotates at at least one of the beam-off speeds. - a particle accelerator for generating the charged particle beam, - a beam delivery device for delivering the charged particle beam to the target, - a beam transport system for transporting the charged particle beam from the particle accelerator to the beam delivery device, - a supporting device for supporting the subject, the beam delivery device being rotatable around the target and with respect to the supporting device and/or the supporting device being rotatable with respect to the beam delivery device, so as to be able to deliver the charged particle beam to the target according to a plurality of irradiation angles (α), - a controller configured to make the beam delivery device rotate at a beam-on speed around the target and with respect to the supporting device and/or to make the supporting device rotate at a beam-on speed with respect to the beam delivery device and to meanwhile irradiate the target with the charged particle beam, the controller is configured to make the beam delivery device rotate around the target at at least two different and non-zero beam-on speeds with respect to the supporting device, a first beam-on speed corresponding to a first irradiation angle (α1) and a second beam-on speed corresponding to a second irradiation angle (α2) among the plurality of irradiation angles (α), and/or the controller is configured to make the supporting device rotate at at least two different and non-zero beam-on speeds with respect to the beam delivery device, a third beam-on speed corresponding to the first irradiation angle (α1) and a fourth beam-on speed corresponding to the second irradiation angle (α2) among the plurality of irradiation angles (α), the controller is further configured to make the beam delivery device rotate at a beam-off speed with respect to the supporting device or vice-versa and meanwhile to stop irradiating the target with the charged particle beam, characterized in that the charged particle beam is a beam of ions, in that the controller is further configured to make the beam delivery device rotate at at least two different and non-zero beam-off speeds with respect to the supporting device or vice-versa, a first beam-off speed corresponding to the first irradiation angle (α1) and a second beam-off speed corresponding to the second irradiation angle (α2) among the plurality of irradiation angles (α), and in that the controller is further configured to change an energy of the particle beam to be delivered to the target while the beam delivery device rotates at at least one of the beam-off speeds.