PROBLEM TO BE SOLVED: To provide a cardio-thoracic ratio calculation device in which a cardio-thoracic ratio is calculated simply and efficiently by a simple method having high reproducibility on the basis of a chest X-ray image.SOLUTION: A cardio-thoracic ratio calculation device includes a measuring position estimation unit for estimating lung right and left end positions and heart right and left end positions in a chest X-ray image, and a cardio-thoracic ratio calculation unit for calculating a cardio-thoracic ratio based on the estimated lung right and left end positions and heart right and left end positions. The measuring position estimation unit detects lung right and left end candidates on the basis of a pixel value and detects heart right and left end candidates on the basis of a differentiated value of the pixel value, concerning a horizontal direction area of the chest X-ray image. Further, the measuring position estimation unit extracts a specific horizontal direction area based on a distance between a lung intermediate point and a heart intermediate point, or a ratio to the lung width determined by the lung right end candidate and the lung left end candidate of the distance, and estimates the extracted lung right and left end candidates and the heart right and left end candidates in the horizontal direction area as the lung right and left end positions and the heart right and left end positions.COPYRIGHT: (C)2015,JPO&INPIT【課題】胸部X線画像に基づいて心胸郭比を単純で再現性の高い方法で簡易に効率よく算出する。【解決手段】胸部X線画像における肺左右端位置、心臓左右端位置を推定する測定位置推定部と、推定された肺左右端位置、心臓左右端位置に基づいて心胸郭比を算出する心胸郭比算出部とを備え、測定位置推定部は、胸部X線画像の水平方向領域について、画素値に基づいて肺左右端候補を検出するとともに、画素値の微分値に基づいて心臓左右端候補を検出し、さらに、肺中間点と心臓中間点との距離、またはその距離の前記肺右端候補と前記肺左端候補とで定められる肺幅に対する割合に基づいて特定の水平方向領域を抽出し、抽出された水平方向領域における肺左右端候補、心臓左右端候補を肺左右端位置、心臓左右端位置として推定する心胸郭比算出装置。【選択図】図1
