Is a catscan or ultrasound better for seeing kidney stones?

Depends: For renal stones (in kidney), ultrasound is usually adequate. Can also see dilation of the kidney when stone is blocking the outflow tube (ureter). For better clear picture and to see ureteral stones which are closer to bladder, ct scan is better. However, all ctscans must be considered carefully given the radiation exposure to the patient which ultrasound does not have.