The ACS head phantom is designed for image evaluation in CT angiography scanning and can be used as an educational tool for medical image interpretation. The head phantom includes a synthetic skull, cervical vertebrae (C1-C7), brain and arteries, along with arteries with contrast medium embedded in the left half of the head. The anterior cerebral artery and middle cerebral artery are three-dimensionally disposed. Diameters of simulated arteries range from approx. 0.5 mm to 4.0 mm.