PROBLEM TO BE SOLVED: To correct an inclination of the ellipse so that an inclination of an ellipse corresponding to an annular part of a fetus becomes close to the inclination of the annular part.SOLUTION: An ellipse corresponding to an annular part of a fetus (e.g., head part of the fetus) is computed based on a tomographic image acquired by the transmission and reception of an ultrasonic wave to and from the fetus in a mothers body. An angle correction part 138 computes an evaluation value in a reference area in each position and at each rotation angle in one axis direction while moving the center of the ellipse in the one axis direction (e.g., short axis direction) of the ellipse, and while rotating the reference area extending in the other axis direction (e.g., long axis direction) of the ellipse around the center after the movement, and corrects the angle of the ellipse with respect to the annular part using the evaluation value.SELECTED DRAWING: Figure 19COPYRIGHT: (C)2019,JPO&INPIT【課題】胎児の環状部位に対応する楕円の傾きがその環状部位の傾きに近くなるように、楕円の傾きを補正する。【解決手段】母体内の胎児に対して超音波を送受波することで得られた断層画像に基づいて、胎児の環状部位(例えば胎児頭部)に対応する楕円が演算される。角度補正部138は、その楕円の中心を楕円の一方軸方向(例えば短軸方向)に移動させながら、かつ、楕円の他方軸方向(例えば長軸方向)に延びる参照エリアを移動後の中心で回転させながら、一方軸方向の各位置及び各回転角度において、参照エリア内の評価値を演算し、その評価値を用いて、環状部位に対する楕円の角度を補正する。【選択図】図19
