An automated method measures coronary calcium in a living subject using x-ray computed tomography (CT). The method acquires at least one CT image containing voxels representing x-ray attenuation of the subject which may or may not be calibrated. The method of analysis may or may not require operator interactions and includes analyzing the images in a computer to identify the boundaries of the heart. The method further includes identifying the approximate location of at least one coronary artery without operator interaction. The method further includes placing a region-of-interest (ROI) surrounding the artery location automatically. The method further includes analyzing the ROI to identify voxels above a threshold value. The method further includes determining the calcium content in mass units.