Radiation therapy system, radiation therapy method and program

A radiation therapy method comprising:

• holding first movement information for moving a tabletop used to fix a patient's body thereon such that a first position of a patient's focus identified by first voxel data imaging an interior of the patient's body matches an isocenter in a dose of a beam administered to the patient's focus;
• holding an irradiation condition, which is set to maximize a focal coverage rate of the patient's focus irradiated with the beam at the first position;
• identifying a second position of the patient's focus by second voxel data imaging the interior of the patient's body immediately before emitting the beam;
• and
• updating the first movement information with second movement information to maximize the focal coverage rate at a position of the patient's focus without changing the irradiation condition.

A non-transitory computer-readable storage medium causing a computer to execute a radiation therapy program comprising the steps of:

• holding first movement information for moving a tabletop used to fix a patient's body such that a first position of a patient's focus identified by first voxel data imaging an interior of the patient's body matches an isocenter in a dose of a beam administered to the patient's focus;
• holding an irradiation condition, which is set to maximize a focal coverage rate of the patient's focus irradiated with the beam at the first position;
• identifying a second position of the patient's focus by second voxel data imaging the interior of the patient's body immediately before emitting the beam;
• and
• updating the first movement information with second movement information to maximize the focal coverage rate at a position of the patient's focus without changing the irradiation condition.