Can a regular CT scan of the brain show blocked arteries?

Indirectly . Can see stroke changes which suggest blocked arteries. Need contrast ct, preferably cta to see arteries.
No. In order to visualize blocked arteries, you would need a high-resolution ct scan and you would need to receive intravenous contrast. A ct scan without contrast can show areas of previous strokes however will not directly show blocked arteries. A good radiologist can also occasionally see calcifications of arteries which could suggest disease however does not necessarily mean the arteries are blocked.