Radiotherapy device comprising a positioning device, and positioning method
A positioning device, a radiotherapy device, and a positioning method enable accurate patient positioning while reducing calculation time. A plurality of X-ray fluoroscopic images are obtained by imaging a patient along each of a plurality of imaging axes in a direction different from a plurality of movement axes along which a treatment couch moves translationally. A plurality of simulated-X-ray fluoroscopic images are obtained by projecting the three-dimensional fluoroscopic image of the patient on each of the plurality of surfaces corresponding to each imaging axis. A similarity calculation unit calculates the similarity between each X-ray fluoroscopic image and each simulated-X-ray fluoroscopic image. Based on the similarity, an optimization calculation processing unit calculates the movement amount of the treatment couch such that each X-ray fluoroscopic image and each simulated-X-ray fluoroscopic image coincide most in each of the plurality of translation directions along each of the plurality of optimization axes.
1 . A positioning device that controls a position of a treatment couch on which a subject is mounted, the positioning device comprising:
an image acquisition unit that acquires a plurality of fluoroscopic images obtained by imaging the subject along each of a plurality of imaging axes in a direction different from a plurality of movement axes along which the treatment couch translationally moves;
a creation unit that creates a plurality of simulated fluoroscopic images obtained by projecting a three-dimensional fluoroscopic image of the subject onto each of a plurality of surfaces corresponding to each imaging axis of the plurality of imaging axes;
a calculation unit that calculates a similarity between each of the plurality of fluoroscopic images and each of the plurality of simulated fluoroscopic images; and
an optimization unit that calculates, based on the similarity, a movement amount of the treatment couch such that each fluoroscopic image and each simulated fluoroscopic image match most in each of a plurality of translation directions along each of a plurality of optimization axes including the plurality of imaging axes and a plurality of rotation directions around a plurality of rotation axes,
wherein each rotation axis of the plurality of rotation axes is identical to an optimization axis of the plurality of optimization axes.
2 . The positioning device according to claim 1 , wherein the plurality of imaging axes is substantially orthogonal to each other.
3 . The positioning device according to claim 1 , wherein a number of the plurality of imaging axes is two.
4 . The positioning device according to claim 3 , wherein a number of the plurality of movement axes is two or more, and
each imaging axis of the plurality of imaging axes is oriented in a direction along a plane formed by any two of the plurality of movement axes.
5 . The positioning device according to claim 1 , wherein the optimization unit further calculates the movement amount of the treatment couch such that a region of interest set on each simulated fluoroscopic image and a region on each fluoroscopic image corresponding to the region of interest match most.
6 . A radiotherapy device comprising:
the positioning device according to claim 1 ;
a treatment-couch control system that moves the treatment couch based on the movement amount calculated by the optimization unit; and
an irradiation device that irradiates the subject mounted on the moved treatment couch with radiation.
7 . A positioning method using a positioning device that controls a position of a treatment couch on which a subject is mounted, the positioning method comprising:
acquiring a plurality of fluoroscopic images obtained by imaging the subject along each of a plurality of imaging axes in a direction different from a plurality of movement axes along which the treatment couch translationally moves;
creating a plurality of simulated fluoroscopic images obtained by projecting a three-dimensional fluoroscopic image of the subject onto each of a plurality of surfaces corresponding to each imaging axis of the plurality of imaging axes;
calculating a similarity between each fluoroscopic image and each simulated fluoroscopic image; and
calculating, based on the similarity, a movement amount of the treatment couch such that each fluoroscopic image and each simulated fluoroscopic image coincide most in each of a plurality of translation directions along each of a plurality of optimization axes including the plurality of imaging axes and a plurality of rotation directions around a plurality of rotation axes,
wherein each rotation axis of the plurality of rotation axes is identical to an optimization axis of the plurality of optimization axes.