Patent ID: 7477930

Claim:
A radiation emission control method in which optical images are obtained using a radiation emission control apparatus, comprising: sequentially obtaining optical images of a test subject having a geometric feature that varies at least partially with respiration of the subject by imaging the subject continuously; sequentially detecting respiratory phases of the test subject simultaneously with the optical imaging based on the geometric feature of the subject on the optical images; emitting radiation rays to the test subject with a radiation source; and controlling the radiation source such that radiation rays are emitted to the test subject when the detected respiratory phase corresponds to an intended respiratory phase during the optical imaging of the subject, wherein a plurality of preliminary optical images are obtained in advance by imaging the test subject continuously at least during the time period from either a maximum inhaled or exhaled state of the test subject to the other; and the respiratory phase detecting comprises: extracting a contour that varies with respiration of the test subject from a predetermined local reference region of the preliminary optical images and optical images; calculating a maximum amount of displacement of the contour in the plurality of preliminary optical images; sequentially detecting the displacement directions of the contour on the optical images based on the plurality of preliminary optical images, and sequentially measuring the amounts of displacement of the contour with reference to the position of the contour at the moment when the displacement direction is reversed; and detecting respiratory phases of the test subject based on the relationship of the amounts of displacement of the contour to the maximum displacement amount.