Radiation therapy system and method of operating radiation therapy apparatus
A radiation therapy system is capable of widening a radiation irradiation range to a patient and includes: a radiation source; a rotation mechanism that supports the radiation source in rotation around an isocenter; a couch that places a therapy target site of a patient at the isocenter; a head swing mechanism that is disposed between the radiation source and the rotation mechanism and that swings an irradiation axis of a radiation emitted from the radiation source by swinging the radiation source; and a controller. The controller holds the head swing mechanism in a state where the irradiation axis of the radiation of the radiation source is shifted from the isocenter in a predetermined direction by a predetermined amount, and rotates the radiation source by the rotation mechanism while emitting the radiation from the radiation source while maintaining the state of the head swing mechanism.
1. A radiation therapy system, comprising:
a radiation source;
a rotation mechanism that supports the radiation source and rotates the radiation source around an isocenter;
a couch that places a therapy target site of a patient at the isocenter;
a head swing mechanism that is disposed between the radiation source and the rotation mechanism and that swings an irradiation axis of a radiation emitted from the radiation source by swinging the radiation source; and
a controller that controls the radiation source, the rotation mechanism, and the head swing mechanism, wherein
the controller holds the head swing mechanism in a state where the irradiation axis of the radiation of the radiation source is shifted from the isocenter in a predetermined direction by a predetermined amount, and rotates the radiation source by the rotation mechanism while emitting the radiation from the radiation source while maintaining the state of the head swing mechanism,
a direction in which the controller shifts the irradiation axis from the isocenter includes a component in a rotation axis direction of the rotation mechanism, and
the controller shifts the irradiation axis from the isocenter in a positive direction in the rotation axis direction, rotates the radiation source by the rotation mechanism in this state, and then shifts the irradiation axis from the isocenter in a negative direction in the rotation axis direction, and rotates the radiation source by the rotation mechanism in this state.
2. The radiation therapy system according to claim 1 , wherein
the controller sets a shift amount of the irradiation axis of the radiation from the isocenter by the head swing mechanism such that the isocenter is included in a range of a spread angle of the radiation emitted from the radiation source.
3. The radiation therapy system according to claim 2 , wherein
an irradiation dose of the radiation in a region including the isocenter is larger than an irradiation dose outside the region.
4. The radiation therapy system according to claim 1 , wherein
a direction in which the controller shifts the irradiation axis from the isocenter includes a component in a radial direction of rotation of the rotation mechanism.
5. The radiation therapy system according to claim 1 , wherein
a multi-leaf collimator is disposed between subject sides of the radiation source, and shields a part of the radiation emitted from the radiation source while rotating with the radiation source by the rotation mechanism.
6. A method of operating a radiation therapy apparatus, comprising:
shifting an irradiation axis of radiation of a radiation source from an isocenter by a predetermined amount in a predetermined direction by a head swing mechanism of the radiation source; and
rotating the radiation source by a rotation mechanism while emitting the radiation from the radiation source while maintaining the above state, wherein
a direction in which the irradiation axis is shifted from the isocenter includes a component in a rotation axis direction of the rotation mechanism, and
the irradiation axis is shifted from the isocenter in a positive direction in the rotation axis direction, the radiation source is rotated by the rotation mechanism in this state, and then the irradiation axis is shifted from the isocenter in a negative direction in the rotation axis direction, and the radiation source is rotated by the rotation mechanism in this state.