Ion beam therapy system and a method for operating the system

An ion beam therapy system comprising:

• a source of ions (300);
• an accelerator system (400) for accelerating ions as a beam (50);
• an ion beam transport system (60) for directing an ion beam from the accelerator to treatment stations (100) to treat patients supported in fixed orientation by patient support (200),
• wherein said ion beam transport system (60) comprises:
• at least a horizontal beam delivery system and at least a gantry (8) rotatable about an axis of rotation,
• said gantry carries optics for receiving the ion beam on its axis of rotation (80), transporting said ion beam away from the axis of rotation and returning the ion beam on a path intersecting the axis at a target isocentre (90) within the patient, delivering said ion beam (50) by rotation of the gantry to said target isocentre (90) from different angles between 0 and 360 degrees;
• said gantry (8) and said horizontal beam delivery system carries means (45, 55) for raster scanning said ion beam (50), enclosing vertical deflection means (45) and horizontal deflection means (55), positioned upstream of a last bending magnet (65), directing said ion beam (50) towards the patient and downstream the last quadrupole lens (75) of said gantry (8),
• characterized in that the system comprises
• the plurality of separate patient treatment stations (100) each having the patient support (200) for orienting a patient in a fixed position;
• and
• wherein said vertical deflection means (45) and said horizontal deflection means (55) for said raster scanning each comprises one scanning magnet and deflects said ion beam (50) perpendicular to its beam axis, so that the beam (50) can be scanned by two scanning magnets over a predetermined controlled area around said target isocentre (90) after passing said last bending magnet (65), which provides a parallel scanning mode by an edge focusing effect at its entrance and exit edges and which comprises a normal conducting last dipole magnet.