An objective of this invention is to realize a high-accuracy two-stage pattern matching (two-stage collating) even in a case that the number of tomographic images of a three-dimensional present image is fewer than that of a three-dimensional reference image when positioning a patient in a radiation therapy. This invention includes a collation processing part (22) which collates a three-dimensional reference image (31) and a three-dimensional present image (36) and calculates a body position correction amount so that the position/posture of an affected part in the present image (36) may be corrected to match the position/posture of the affected part in the reference image (31). The collation processing part (22) has a primary collating part (16) for performing a primary collation which collates the reference image (31) with the present image (36) and a secondary collating part (17) for performing a secondary collation which collates a specified template area (40) generated from either one of the reference image (31) or the present image (36) based on the result of the primary collation, with a specified retrieval object area (42) generated from the other one of the reference image (31) or the present image (36), which is different from the generation origin of the specified template area (40), based on the result of the primary collation.本發明之目的在於:在進行放射線治療的患者定位之際,即使是三維現在畫像的斷層畫像數比三維基準畫像少之情況,也能夠實現高精度的兩階段型樣匹配(兩階段核對)。本發明具備有:核對三維基準畫像31與三維現在畫像36,計算出讓現在畫像36中的患部的位置姿勢與基準畫像31中的患部的位置姿勢一致之體位修正量之核對處理部22。核對處理部22具有:進行從基準畫像31相對於現在畫像36之一次核對之一次核對部16;以及進行從根據一次核對的結果而從基準畫像31或現在畫像36之一方所生成的預定的樣板區域40,相對於根據一次核對的結果而從與預定的樣板區域40的生成基礎不同之基準畫像31或現在畫像36之另一方所生成的預定的檢索對象區域42之二次核對之二次核對部17。16...一次核對部17...二次核對部18...基準樣板區域產生部21...三維畫像輸入部22...核對處理部23...核對結果顯示部24...核對結果輸出部25...位置姿勢變換部26...治療台控制參數算出部29...畫像核對裝置30...患者定位裝置
