Is there a lot of radiation associated with a ct scan with contrast for the renal area? can the contrast cause an allergic reaction?

No: CT of abdomen is a fairly routine test and not considered a radiation danger. Th incidence of allergic reaction to contrast is 1-3% with non-ionic agents and 4-12% with ionic contrast agents.Non-contrast agents are the type generally used today. The benefit from the diagnostic value of the test far exceeds the risk of these 2 issues. Hope this answers your question.