This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CT SCAN, Subject name: Radiology
[{'content': 'Retinoblastoma best evaluated by- \nSelect and explain. \nA. Ultrasonography, B. CT SCAN, C. CT SCAN + MRI, D. MRI', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Retinoblastoma: To detect calcification in orbit: CT Scan To evaluate nerve invasion: MRI(preferred) 2nd MC cancer in patient with retinoblastoma- osteosarcoma MC bone tumor that develops after radiotherapy to bones: osteosarcoma Trilateral retinoblastoma (TRb): bilateral retinoblastoma (Rb) + Pineal Gland tumor Quadrilateral retinoblastoma: Trilateral retinoblastoma + supracellular mass INTRAORBITAL CALCIFICATION: RETINOBLASTOMA', 'role': 'assistant'}]