Gantry for particle therapy as an arm rotating in the longitudinal plane

Abstract

A system for particle beam therapy has an adjustable gantry for beam delivery to a patient site. The gantry has a beam coupling section, a first beam bending section with beam deflection and/or focusing magnets. A beam transport section receiving the particle beam from the first beam bending section and guiding the particle beam to a second beam bending section. The beam exits at a window of a beam nozzle. A patient table/chair is rotatable in the horizontal plane or in a plane being parallel to the horizontal plane and optionally being adjustable vertically. The gantry is supported by a tilting mechanism allowing the gantry to be tilted vertically by an angle 1[90; +90]. A rotation mechanism is disposed in a way that the second beam bending section and the beam nozzle are rotatable by an angle 2[180; +180] around a direction given by the angle 1.

Claims

1. A system for particle beam therapy, the system comprising, as seen in a flow direction of a particle beam: a) an adjustable gantry for beam delivery to a target volume, said gantry including: a1) a beam coupling section for an incoming particle beam, the incoming particle beam being oriented substantially horizontally and defining a horizontal plane; a2) a first beam bending section having a plurality of beam deflection and/or focusing magnets, said first beam bending section being configured to either bend the particle beam with an adjustable angle into a vertical plane, or with 90 degrees in the horizontal plane, but with mechanical rotatability about an adjustable angle along an axis of the incoming particle beam; a3) a beam transport section disposed to receive the particle beam leaving said first beam bending section and guiding the particle beam to a second beam bending section; a4) said second beam bending section having a plurality of beam deflection magnets and/or beam focusing magnets; and a5) a beam nozzle formed with a window for an exit of the particle beam; and b) a patient support mounted for rotation and/or shifting in the horizontal plane or in a plane parallel to the horizontal plane; c) a tilting mechanism supporting said gantry to enable said gantry to be tilted vertically by a tilting angle .sub.1, where .sub.1[90; +90], about a pivot disposed in a region of said first beam bending section; and d) a rotation mechanism disposed to enable said second beam bending section and said beam nozzle to rotate by an angle .sub.2, where .sub.2[180; +180], around a direction given by the tilting angle .sub.1.

2. The system according to claim 1, comprising the following basic settings: a) maximum of .sub.1 and .sub.2=0, leading to a particle beam pointing from the vertical direction downwards to said patient support; b) minimum of .sub.1 and .sub.2=180, leading to a particle beam pointing from the vertical direction upwards to said patient support; c) .sub.1=0and .sub.2=90, leading to a particle beam pointing in the horizontal direction from one side to said patient support; and d) .sub.1=0and .sub.2=+90, leading to a particle beam pointing in the horizontal direction from an opposite side to said patient support.

3. The system according to claim 1, wherein said tilting mechanism comprises a telescope arm.

4. The system according to claim 1 wherein said beam transport section comprises a telescope section.

5. The system according to claim 4, wherein said beam transport section is adjustable in length in order to compensate for a change in a horizontal component of said gantry due to the tilting angle .sub.1.

6. The system according to claim 1, wherein said first beam bending section comprises a set of magnets in order to deflect the incoming beam into a direction given by the tilting angle .sub.1.

7. The system according to claim 1, which comprises a beam spreading system configured to spread the beam in a lateral direction, which is perpendicular to a direction of the beam leaving said second bending section.

8. The system according to claim 7, wherein said beam spreading system comprises a scattering system configured to increase a beam diameter and/or a system of fast deflection magnets configured to scan the beam in the transversal direction.

9. The system according to claim 8, wherein said beam spreading is collated upstream of or downstream of said second bending section in the flow direction of the beam.

10. The system according to claim 1, wherein a treatment angle of the particle beam at the isocenter with respect to a patient orientation is determined by a combination of the tilting angle .sub.1, the angle .sub.2, and an orientation of the patient support.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 schematically a perspective view on a first system for particle therapy;

(2) FIG. 2 schematically a perspective view on a second system for the particle therapy that is only slightly amended as compared to FIG. 1;

(3) FIG. 3 schematically the position of the system according to FIG. 1 when the particle beam is led vertically downwards (a) and vertically upwards (b);

(4) FIG. 4 schematically the position of the system according to FIG. 1 when the particle beam is led horizontally from one side; (a) is a view from the side and (b) is the view from above; and

(5) FIG. 5 schematically a simplified block diagram of a system for particle therapy in accordance with another particular embodiment of the invention.

DESCRIPTION OF THE INVENTION

(6) FIG. 1 schematically shows a first system 2 for particle beam therapy delivery. The system 2 comprises for an incoming particle beam 4 a beam coupling section 6 being following by a first bending section 8. In the present example, a gantry 10 is supported by a tilting mechanism 24 allowing the gantry 10 to be tilted vertically (along the z-axis) by an first angle .sub.1, .sub.1[90; +90], wherein the gantry 10 comprises the bearing (pivot) 7 being disposed at the entrance of the beam coupling section 6 in order to enable a declination of the complete gantry 10 in the z-direction. The first bending section 8 bends the particle beam 4, such as a proton beam or an ion beam, in the vertical yz plane with an angle .sub.1.

(7) Further, a second bending section 18 and a beam nozzle 20 can be rotated by a rotation mechanism 26 being disposed in a way that the second beam bending section 18 and the beam nozzle 20 being rotatable by an angle .sub.2, .sub.2[180; +180] around a direction given by the angle .sub.1, but preferably .sub.2[0; +180], to limit the footprint of the gantry.

(8) In addition, a beam transport section 16 connecting the first beam bending section 8 to the second bending section 18 can be telescopically adjustable with respect to the length of this beam transport section 16 and allows a variation in length of approximately 0.5 m.

(9) In the shown example, the second beam bending section 18 bends the beam by a fixed angle in the range of 90-135 degrees. This second bending section 18 is rotatable along an axis that approximately equals the direction given by .sub.1 of the unscanned (or central) beam entering the second beam bending section 18. This rotation angle .sub.2 covers at least 180 degrees, between 0 degr. (aiming the beam downwards) and +180 degr (aiming upwards). The appropriate value for .sub.2 is a function of .sub.1. The combination of .sub.1 and .sub.2 determines the incident angle of the beam direction at the patient.

(10) The following three main incident direction can be established: When .sub.1 is maximal (+) and .sub.2=0, the particle beam 4 points from the vertical direction down to the patient (see FIG. 3(a)). When .sub.1 is minimal () and .sub.2=180, the particle beam 4 points in the vertical direction upwards to the patient (see FIG. 3(b)). When .sub.1=0 and .sub.2=90, the particle beam 4 points in the horizontal direction to the patient (see FIGS. 4 (a) and (b)).

(11) In all orientations small deviations can be added to .sub.1 and .sub.2 by small bending magnets (steering magnets) for fine tuning the incident angle at the patient. A nozzle 20 at the exit of the second bending section 18 can comprise equipment to verify the applied dose and the beam characteristics. A patient table 22 is part of a positioning system that can shift and rotate the patient position in the horizontal plane. The range of this adjustment must be large enough to compensate the motion of the isocenter as a function of .sub.1 and .sub.2.

(12) In order to have a common understanding on the direction, the following definitions are applied: The horizontal plane is the plane at the height of the particle beam 4 exiting the second beam bending section 18, when .sub.1 is at 0. This is usually equal to the level of the incoming particle beam 4 at the coupling section 6. The treatment angle is the angle of the particle beam at the isocenter with respect to the patient orientation and it is determined by a combination of the .sub.1 and .sub.2 and the orientation of the patient table/chair 22. The isocenter is the location where the beam coming out of the nozzle 20 is crossing the horizontal plane. Typically, .sub.2 is determined by the value of .sub.1 but can be chosen differently in case of exceptional treatment angles or treatment target locations.

(13) The components from the beam transport section 16 until and including the second beam bending section 18 are mounted such that these are always aligned in a mechanical stable or corrected position. The isocenter position is not fixed in space and moves along a curve in the horizontal plane as a function of .sub.1. The shape of this curve depends on whether use is made of the option to have an adjustable (telescopable) length of the beam transfer section 16 which is located between the first beam bending section 10 and the second beam bending section 18. In that case, the length of this beam transport section 16 is a function of .sub.1. This option enables that the isocenter position moves along a straight line in the horizontal plane. This is advantageous for daily checks and in connection to imaging devices that verify the patients positioning with respect to the gantry. However, with appropriate tools for these checks, a curved trajectory of the isocenter position as a function of .sub.1 and .sub.2 is also possible.

(14) The second beam bending section 18 can be designed such that it rotates over a .sub.2 range of >360 degrees or >180 degrees. The 180 degrees version has major advantages, such as a smaller treatment room, less moving range of the patient table 22 and easier rotation construction. This is the version shown in the figures.

(15) Possible advantages of here proposed mechanical layout are: a reduction of the treatment room footprint with respect to that of a conventional gantry; very simple mechanical construction to move the second beam bending section 18 up and down; it is possible to mount a degrader and/or scanning system (sweeper magnets) in the beam transfer section 16 between the first bending section 8 and the second beam bending section 18 or the beam scanning system can be mounted in the nozzle 20 of the second beam bending section 18; Compared with conventional gantries the two rotational axes allow one additional degree of freedom in the choice of how a treatment angle is constructed.

(16) In a preferred embodiment, the system 2 may additionally comprise a beam spreading system 30 to spread the beam in the lateral direction, which is perpendicular to the direction of the beam leaving the second bending section 18. The beam spreading system 30 can comprise a scattering system 32 that increases the beam diameter and/or a system of fast deflection magnets 34 that scan the beam in the transversal direction. The beam spreading system 30 can be collated before 36 (upstream of) or behind 38 (downstream of) the second bending section 18.

(17) FIG. 2 schematically shows a system 2 for a therapy using the particle beam 4 that is slightly amended as compared to the system 2. Presently, the particle beam 4 which is generated in a linear accelerator and/or a cyclotron and/or a synchrotron is delivered horizontally along the x-direction to a particle beam gantryin the following referred to as gantry 10. Said gantry 10 comprises a coupling section 6. At this coupling section 6, the gantry 10 can be rotated over an angle 1 along the x-axis by a rotation bearing 7. Beside this rotation bearing 7, the coupling section 6 provides beam focusing (collimators) and beam control/diagnosis equipment (not shown in detail) before the particle beam 4 enters into a first bending section 8. Usually, this first bending section 8 comprises a number of dipole and/or quadrupole magnets 12, 14 which are controlled to bend the particle beam 4 by its magnetic fields into a desired direction. In the present example, the first beam bending section 8 bends the particle beam 4 from the x-direction into the y-direction, so over an angle of 90 degrees in the horizontal plane, if the first bending section 8 is not rotated.

(18) The first beam bending section 8 is followed by the beam transport section 16 receiving the particle beam 4 leaving the first beam bending section 8 and guiding the particle beam 4 to a second beam bending section 18. The beam transport section 16 may comprise further equipment for the beam diagnosis and sweeper magnets as for example known from the WO 2013/149945 A1.

(19) The second beam bending section 18 comprises a number of beam deflection magnets and/or beam focusing magnets in order to deliver the particle beam 4 via the beam nozzle 20 comprising a window for the exit of the particle beam 4 out of the gantry 10 to the patient table 22. The patient table 22 could also comprise a patient chair allowing a patient to be treated in upright position. The patient table/chair 22 is rotatable and/or shiftable in the horizontal plane (given here by the x-and y-axis). Optionally, the patient table/chair may be adjustable vertically, too.

(20) In the present example, the gantry 10 is supported by the tilting mechanism 24 allowing the gantry 10 to be tilted vertically (along the z-axis, in the yz-plane) by a first angle .sub.1, .sub.1[90; +90], wherein the gantry 10 comprises the rotation bearing (pivot) 7 being disposed at the entrance of the beam coupling section 6 in order to enable a rotation of the complete gantry 10 along the x-axis. Further, the second bending section 18 and the beam nozzle 20 can be rotated by the rotation mechanism 26 being disposed in a way that the second beam bending section 18 and the beam nozzle 20 being rotatable by an angle .sub.2, .sub.2[180; +180], but preferably .sub.2[0; +180] in order to limit the footprint of the gantry 10) around a direction given by the angle .sub.1.

(21) Typically, the range of the first angle .sub.1 depends on the design of the system 2. For the system 2, the range of the first angle .sub.1 can typically be between approximately 40 and +40. After the first bending section 8 the out-coming beam 4 is aimed into the .sub.1-direction with respect to the horizontal plane: downwards when .sub.1<0 and upwards when .sub.1>0. Due to the bending in the horizontal plane, the first bending section 8 can be designed such that it can also serve as an energy selection system.