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
Which of the following is the most sensitive imaging modality for the diagnosis of ureteric stones in a patient with acute colic? 
Select and explain. 
A. X-ray KUB region, B. Abdominal ultrasound, C. Non contrast CT scan of the abdomen, D. Contrast enhanced CT scan of the abdomen
C: Non contrast CT scan of the abdomen
Answer: C: Non contrast CT scan of the abdomen 
Explanation: The most sensitive imaging modality for diagnosis of ureteric stones in a patient with acute colic is non contrast CT scan of abdomen. It has a sensitivity and specificity greater than 90%. Advantages of using it are: It avoids problems due to intravenous contrasts, allows diagnosis of non urological pathology. Disadvantage: It is associated with significant exposure to ionizing radiation (2.5cGy). Ref: Emergency Surgery By Adam Brooks, Page 127; SRB's Manual of Surgery By Sriram Bhat, 3rd Edition, Page 959