An image processing apparatus according to an embodiment includes a lung field region extracting unit, a lung field bottom region extracting unit, and a detecting unit. The lung field region extracting unit is configured to extract, based on pixel values of pixels constituting a three-dimensional medical image capturing a chest of a subject, a lung field region from the three-dimensional medical image. The lung field bottom region extracting unit is configured to extract a lung field bottom region from the lung field region. The detecting unit is configured to detect a vertex position of the lung field bottom region on the head side of the subject.
