Radiation treatment system comprising a CT apparatus, a treatment planning apparatus, and a radiation control apparatus, radiation control method, and storage medium

A radiation treatment system comprising:

• a treatment planning apparatus that creates a treatment plan for a radiation treatment of a subject;
• a radiation treatment apparatus that includes a gantry and a radiation beam source mounted on the gantry, and is configured to irradiate the subject with a radiation beam from the radiation beam source in a case, where the subject is positioned along a rotational axis of the gantry;
• a fluoroscopic image generation apparatus that is arranged approximately coaxially with the rotational axis and generates a fluoroscopic image of the subject;
• and
• a radiation control apparatus that controls radiation of the radiation beam from the radiation beam source toward the subject, based on the treatment plan for the radiation treatment and the fluoroscopic image of the subject, wherein:
• the treatment plan includes a computed tomography image at a specific respiratory phase of the subject and isocenter coordinates for specifying an irradiation position of the radiation beam at the specific respiratory phase of the subject;
• the radiation control apparatus includes one or more processors and a memory storing computer-executable instructions configured to cause the one or more processor to function as:
• a treatment plan acquiring section that acquires the treatment plan from the treatment planning apparatus;
• a digitally reconstructed radiograph image generating section that generates a digitally reconstructed radiograph image of the subject for each prescribed angle of the gantry, based on the computed tomography image and the isocenter coordinates included in the acquired treatment plan;
• a fluoroscopic image acquiring section that acquires the fluoroscopic image of the subject and a rotational angle of the gantry at a time when the fluoroscopic image of the subject was generated, from the fluoroscopic image generation apparatus;
• a positional deviation calculating section that calculates a positional deviation between a position of a diaphragm of the subject in the generated digitally reconstructed radiograph image of the subject and a position of the diaphragm of the subject in the acquired fluoroscopic image of the subject, for a same rotational angle;
• and
• a radiation permission determining section that permits radiation of the radiation beam from the radiation beam source toward the subject, when the positional deviation is less than or equal to a prescribed value;
• and
• the positional deviation calculating section:
• generates a plurality of shift images by shifting the fluoroscopic image of the subject by a prescribed increment along a craniocaudal direction of the subject, within a prescribed range in the craniocaudal direction;
• calculates a normalized correlation coefficient between the digitally reconstructed radiograph image of the subject and each of the generated plurality of shift images;
• and
• determines a shift amount of a shift image corresponding to a largest normalized correlation coefficient among a plurality of calculated normalized correlation coefficients, relative to the digitally reconstructed radiograph image of the subject in the craniocaudal direction, to be the positional deviation.

A radiation control method for controlling radiation of a radiation beam from a radiation beam source toward a subject, based on a treatment plan for the subject and a fluoroscopic image of the subject, wherein:

• the treatment plan includes a computed tomography image at a specific respiratory phase of the subject and isocenter coordinates for specifying an irradiation position of the radiation beam at the specific respiratory phase of the subject;
• the radiation beam source is mounted on a gantry, and is configured to irradiate the subject with the radiation beam when the subject is positioned along a rotational axis of the gantry;
• and
• the fluoroscopic image of the subject is generated by a fluoroscopic image generation apparatus arranged approximately coaxially with the rotational axis of the gantry;
• the radiation control method comprises:
• a first step of acquiring the treatment plan;
• a second step of generating a digitally reconstructed radiograph image of the subject for each prescribed angle of the gantry, based on the computed tomography image and the isocenter coordinates included in the acquired treatment plan;
• a third step of acquiring the fluoroscopic image of the subject and a rotational angle of the gantry at a time when the fluoroscopic image of the subject was generated;
• a fourth step of calculating a positional deviation between a position of a diaphragm of the subject in the generated digitally reconstructed radiograph image of the subject and a position of the diaphragm of the subject in the acquired fluoroscopic image of the subject, for a same rotational angle;
• and
• a fifth step of permitting radiation of the radiation beam from the radiation beam source toward the subject, in a case where the positional deviation is less than or equal to a prescribed value;
• and
• the fourth step includes:
• generating a plurality of shift images by shifting the fluoroscopic image of the subject by a prescribed increment along a craniocaudal direction of the subject, within a prescribed range in the craniocaudal direction;
• calculating a normalized correlation coefficient between the digitally reconstructed radiograph image of the subject and each of the generated plurality of shift images;
• and
• determining a shift amount of a shift image corresponding to a largest normalized correlation coefficient among a plurality of calculated normalized correlation coefficients, relative to the digitally reconstructed radiograph image of the subject in the craniocaudal direction, to be the positional deviation.