1. An image diagnostic processing device configured to judge whether an anatomic abnormal region exists in an image representing the inside of a subject, the device comprising: a processing unit configured to determine a threshold value for determining an abnormal candidate region including a ground glass opacity and to perform a thresholding-process with respect to the image using the determined threshold value to obtain a two-value image; a generating unit configured to generate a penalty image from the two-value image; and a determining unit configured to fit a spherical or ellipsoidal model to the penalty image to determine the abnormal candidate region including the ground glass opacity.