It because of longer duration of ct pet bone scan?

is it because of longer duration of ct pet bone scan?

Hi Rohan. This table is meant to help you remember conceptually varios modalities by using the Green-Yellow-Red analogy. There are a few exceptions to this concept - and you have pointed one out here. Yes Barium enema has a higher exposure than Bone scan / CT Head - but protecting a patient in Ba enema by using a lead shield is easier. A CT tube rotates all around the patients body so its very difficult to shield. Also CT is more commonly done now - even in children and hence CT beaing the Red zone is more apt.

thank u sir got it