Final answer:
A subdural hematoma on a head CT scan appears as a crescent-shaped or lenticular-shaped collection of hyperdense blood located between the brain and the skull.
Step-by-step explanation:
A subdural hematoma is a collection of blood that forms between the dura mater (the outermost layer of the brain) and the arachnoid mater. On a head CT scan, a subdural hematoma appears as a crescent-shaped or lenticular-shaped collection of hyperdense (bright) blood located between the brain and the skull.
The hyperdensity of the blood is due to its higher density compared to normal brain tissue. The shape of the hematoma can help differentiate it from other intracranial lesions, such as epidural hematoma or brain tumors.
It's important to note that the appearance of a subdural hematoma on a head CT scan can vary depending on the age of the hematoma. Acute hematomas may appear hyperdense, while subacute or chronic hematomas may appear hypodense (darker) due to degradation of the blood products over time.