This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
[{'content': 'Which of the following is not true about non contrast CT scan in head injury? \nSelect and explain. \nA. Subdural hematoma increase in density over lesional CT scans over weeks, B. Extra dural haematomas are usually lens shaped, C. Acute subdural hematoma appears as crescent shadow of increased density, D. Subarachnoid haemorrhage appears as areas of increased density in basilar cisterns', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Subdural hematoma increase in density over lesional CT scans over weeks', 'role': 'assistant'}]