An image processing device (1) comprises : an image data acquisition unit (10) for acquiring SPECT image data of a brain a brain-region ROI definition unit (13) for defining a brain-region ROI in the SPECT image a striatum ROI definition unit (14) for defining a striatum ROI in the SPECT image a histogram generation unit (15) for generating a histogram whose horizontal axis represents the class of counts and whose vertical axis represents the frequency of unit region for each class a threshold determination unit (16) for, based on counts in the SPECT image’s background which is the brain-region ROI except the striatum ROI, determining a threshold for distinguishing ventricles and sulci in the SPECT image a region distinction unit (17) for distinguishing between a region whose number of counts is smaller than or equal to the threshold and a region whose number of counts is larger than the threshold and an SBR calculation unit (18) for calculating an SBR (Specific Binding Ratio) with the exception of the region whose number of counts is smaller than or equal to the threshold. This allows for using only nuclear medicine image data to eliminate the influence of ventricles and sulci in the calculation of the SBR.影像處理裝置(1),其包含:影像資料取得部(10),其取得腦部之SPECT影像資料;腦區域ROI設定部(13),其於SPECT影像上設定腦區域ROI;紋狀體ROI設定部(14),其於SPECT影像上設定紋狀體ROI;直方圖生成部(15),其生成橫軸為計數值之組距,縱軸為與上述組距對應之單位區域之次數之直方圖;臨限值決定部(16),其基於自腦區域ROI將紋狀體ROI排除在外之SPECT影像之背景之計數值,決定用以判斷SPECT影像中之腦室及腦溝之臨限值;區域判斷部(17),其對計數值為臨限值以下之區域及較臨限值大之區域進行判斷;及SBR計算部(18),其將臨限值以下之區域排除在外,計算SBR(Specific Binding Ratio)。藉此,於SBR之計算中,可僅使用核醫影像資料,去除腦室或腦溝之影響。1‧‧‧影像處理裝置10‧‧‧影像資料取得部11‧‧‧控制部12‧‧‧輸出部13‧‧‧腦區域ROI設定部14‧‧‧紋狀體ROI設定部15‧‧‧直方圖生成部16‧‧‧臨限值決定部17‧‧‧區域判斷部18‧‧‧SBR計算部
