PROBLEM TO BE SOLVED: To derive a high-precision optimumly-set sound velocity while keeping the number of times of transmission of ultrasonic waves small.SOLUTION: The depth position of each of a plurality of transmission focuses is derived so that the plurality of transmission focuses can be arrayed in mutually-different depth positions within an input region of interest and so that the distance between the transmission focus and the adjacent transmission focus can be increased as the depth position of the transmission focus becomes deeper, in a depth area in which a transmission F-value is changed depending on a focus distance. An estimated value of a sound velocity in the region of interest is derived as an optimumly-set sound velocity on the basis of a reception signal obtained by applying transmission focusing to each of the derived depth positions.COPYRIGHT: (C)2014,JPO&INPIT【課題】超音波の送信回数を抑えつつ高精度な最適設定音速を導出する。【解決手段】入力された着目領域内の互いに異なる深さ位置に複数の送信焦点を配置するように、且つ送信F値が焦点距離に応じて変化する深さ領域において、送信焦点の深さ位置が深くなるに従って隣接する送信焦点との距離が増していくように複数の送信焦点の各々の深さ位置を導出する。導出された深さ位置の各々に送信フォーカスを実施して得られた受信信号に基づいて着目領域の音速の推定値を最適設定音速として導出する。【選択図】図1
