This method involves: creating a histogram of pixel values on the basis of a CT image； determining a soft region peak, which is the peak in a soft tissue region in the histogram； and, on the basis of the soft region peak, setting a threshold value representing the lower limit of the class value of a bone region in the histogram. The method may optionally include automatic removal of the bed platform portion from the CT image.本發明係自CT影像中自動抽取骨區域。較佳之實施形態包括如下步驟：基於CT影像製作像素值之直方圖；決定直方圖中作為軟組織區域之峰的軟組織區域峰；及基於軟組織區域峰設定表示直方圖中之骨區域之組值之下限之臨限值。亦可包括自CT影像中自動去除床鋪部分之步驟。
