Reduction of a linear accelerator (linac) isocenter size through adaptive control of a source position
AssigneeVarian Medical Systems, Inc.
InventorJoao SILVEIRA
Life of this patent
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Abstract
A radiation therapy (RT) system has a C-arm gantry with a gantry head that bends downward due to gravity. This downward bending causes a central beam axis of a treatment beam from the gantry head to be misaligned/offset/deviated relative to an isocenter, thereby increasing an isocenter size (maximum delivery error). A source of the treatment beam and a field center of a collimator provide two points that define the central beam axis. A position of the source can be adjusted/changed to tune the central beam axis to the isocenter, thereby compensating for the misalignment/offset/deviation and reducing the isocenter size.
Claims20
A radiation therapy (RT) system, comprising:
- a gantry having a linear accelerator, wherein the gantry is rotationally movable to position the gantry at a plurality of gantry angles, and wherein at any of the gantry angles, the gantry is configured to direct a treatment beam generated by the linear accelerator towards a target;
- a source of the treatment beam at the linear accelerator;
- a collimator at the gantry and having a field center, wherein a central beam axis of the treatment beam is defined by the source and the field center;
- a couch that provides the target where the treatment beam is directed;
- and
- at least one controller operatively coupled to the source, the collimator, or the couch, wherein for any particular gantry angle of the plurality of gantry angles, the at least one controller is configured to change a position of at least one of the source, the field center, or the couch to align the central beam axis of the treatment beam to the target.
A radiation therapy (RT) system, comprising:
- a gantry having a linear accelerator, wherein the gantry is rotationally movable to position the gantry at a plurality of gantry angles, and wherein at any of the gantry angles, the gantry is configured to direct a treatment beam generated by the linear accelerator towards a target;
- a source of the treatment beam at the linear accelerator;
- a collimator at the gantry and having a field center, wherein a central beam axis of the treatment beam is defined by the source and the field center;
- a couch that provides the target where the treatment beam is directed;
- and
- a controller operatively coupled to the source, wherein for any particular gantry angle of the plurality of gantry angles, the controller is configured to change a position of the source to compensate for an offset of the central beam axis of the treatment beam relative to an isocenter where the target is placed so as to align the central beam axis of the treatment beam to the isocenter.
A computer-implemented method to reduce a size of an isocenter in a radiation therapy (RT) system, the method comprising:
- determining an offset of a central beam axis of a treatment beam relative to the isocenter, wherein the RT system includes a gantry having a linear accelerator, wherein the gantry is rotationally movable to position the gantry at a plurality of gantry angles, wherein at any particular gantry angle of the gantry angles, the gantry is configured to direct the treatment beam which is generated by the linear accelerator towards the isocenter where a target is placed, and wherein the offset is determined for each of the plurality of gantry angles;
- for a particular gantry angle, compensating for the offset determined for the particular gantry angle by changing a position of a source of the treatment beam, wherein the central beam axis of the treatment beam is defined by the source and a field center of a collimator;
- and
- directing the treatment beam, from the source with the changed position, towards the target with the central beam axis being coincident with the isocenter.
Dependencies are inferred from the claim text.