This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
Maximum radiation exposure is by 
Select and explain. 
A. Radiography, B. CT abdomen, C. Radionuclide scan, D. X-ray Abdomen
B: CT abdomen
Answer: B: CT abdomen 
Explanation: Examination Effective total dose (mSv) Chest radiograph 0.06 Skull radiograph 0.2 Pelvis radiograph 0.65 Lumbar spine radiograph 1.3 Upper GI series (Barium) 2.45 Abdomen radiograph 0.55 Barium enema 2.8 to 4 IVP/IVU 1.6 Extremities 0.01 Enteroclysis 1.5 CT chest 8 CT abdomen 10 CT head 3.5 RNI 4.8