A radiotherapy apparatus control apparatus comprising: an imaging section configured to use diagnostic X-ray sources (24, 25) and sensor arrays (32, 33) included in a radiotherapy apparatus; a matching degree calculating section configured to calculate a matching degree between each template (61-1, 61-2, 61-3) of a template set and a plurality of transmission images (65-1, 65-2, 65-3) imaged by using radiation (35, 36) transmitting through a patient from said diagnostic X-ray sources (24, 25) to said sensor arrays (32, 33) at different times under the control of the radiotherapy apparatus control apparatus and before performing the radiotherapy; a selecting section configured to select a template transmission image from the plurality of transmission images (65-1, 65-2, 65-3) based on the matching degrees; a template generating section configured to add a new template, which is generated based on said template transmission image, to said template set; each of the plurality of matching degrees indicating a similarity between a portion of a corresponding one of said plurality of transmission images (65-1, 65-2, 65-3) and one template (61-1, 61-2, 61-3) of said template set; said imaging section being configured to image a location measurement transmission image from radiation (35, 36) transmitting through said patient from said diagnostic X-ray sources (24, 25) to said sensor arrays (32, 33) during the radiotherapy; a template matching section configured to perform pattern-matching of each of templates (61-1, 61-2, 61-3) of said template set with said location measurement transmission image and selects an optimal template which is the most similar to a portion of the location measurement transmission image, from said template set; a location calculating section configured to calculate a location of a specific site of said patient based on said location measurement transmission image and said optimal template; a driving section configured to control a driving unit to drive a radiation irradiating unit to said patient based on the specific site location such that therapeutic radiation transmits through said specific site location; and an irradiating section configured to control said radiation irradiating unit to irradiate the therapeutic radiation, whereby the radiotherapy apparatus control apparatus allows the operation of modifying the templates in said template set depending on a matching degree calculated between each of the templates and the location of a region in the location measurement transmission images obtained during the radiotherapy, after the operation of performing the radiotherapy is stopped by the user. an imaging section configured to use diagnostic X-ray sources (24, 25) and sensor arrays (32, 33) included in a radiotherapy apparatus; a matching degree calculating section configured to calculate a matching degree between each template (61-1, 61-2, 61-3) of a template set and a plurality of transmission images (65-1, 65-2, 65-3) imaged by using radiation (35, 36) transmitting through a patient from said diagnostic X-ray sources (24, 25) to said sensor arrays (32, 33) at different times under the control of the radiotherapy apparatus control apparatus and before performing the radiotherapy; a selecting section configured to select a template transmission image from the plurality of transmission images (65-1, 65-2, 65-3) based on the matching degrees; a template generating section configured to add a new template, which is generated based on said template transmission image, to said template set; each of the plurality of matching degrees indicating a similarity between a portion of a corresponding one of said plurality of transmission images (65-1, 65-2, 65-3) and one template (61-1, 61-2, 61-3) of said template set; said imaging section being configured to image a location measurement transmission image from radiation (35, 36) transmitting through said patient from said diagnostic X-ray sources (24, 25) to said sensor arrays (32, 33) during the radiotherapy; a template matching section configured to perform pattern-matching of each of templates (61-1, 61-2, 61-3) of said template set with said location measurement transmission image and selects an optimal template which is the most similar to a portion of the location measurement transmission image, from said template set; a location calculating section configured to calculate a location of a specific site of said patient based on said location measurement transmission image and said optimal template; a driving section configured to control a driving unit to drive a radiation irradiating unit to said patient based on the specific site location such that therapeutic radiation transmits through said specific site location; and an irradiating section configured to control said radiation irradiating unit to irradiate the therapeutic radiation, whereby the radiotherapy apparatus control apparatus allows the operation of modifying the templates in said template set depending on a matching degree calculated between each of the templates and the location of a region in the location measurement transmission images obtained during the radiotherapy, after the operation of performing the radiotherapy is stopped by the user.