The present therapy planning system for neutron capture therapy creates therapy plans for neutron capture therapy, in which a subject is irradiated with a neutron beam, wherein the system is provided with: an image-acquiring unit for acquiring an image of the subject a body outline setting unit for setting a body outline of the subject on the basis of an image acquired by the image-acquiring unit a vacancy region setting part that sets a portion inside the body outline set by the body outline setting unit and in which image pixel values are within a predetermined range as a vacancy region in which a vacancy is disposed and a mucosa region setting unit that sets a portion inside the body outline and encompassing a first thickness outside of the surface of the vacancy region set by the vacancy region setting part as a mucosa region in which a mucosa is disposed.本發明提供一種能夠進行適於中子捕獲治療法之治療計劃之中子捕獲治療法用治療計劃系統。治療計劃系統(100)具備空孔區域設定部(116),其在身體輪廓設定部(111)所設定之身體輪廓(50)的內側設定圖像的畫素值在既定範圍內之部分作為配置有空孔之空孔區域(56)。由身體輪廓設定部(111)設定身體輪廓(50),空孔區域設定部(116)判定身體輪廓(50)的內側的畫素值,藉此能夠設定空孔區域(56)。黏膜區域設定部(117)能夠設定從由空孔區域設定部(116)設定之空孔區域(56)的表面向外側相當於第1厚度(t1)之部分作為配置有黏膜之黏膜區域(57)(參閱圖6)。這樣,藉由設定空孔區域(56),能夠容易設定黏膜區域(57)。100‧‧‧治療計劃系統101‧‧‧處理部102‧‧‧輸入部103‧‧‧顯示部104‧‧‧記憶部110‧‧‧圖像獲取部111‧‧‧身體輪廓設定部112‧‧‧骨區域設定部113‧‧‧器官區域設定部114‧‧‧空氣區域設定部115‧‧‧皮膚區域設定部116‧‧‧空孔區域設定部117‧‧‧黏膜區域設定部
