Unenhanced helical CT for renal colic - is the radiation dose justifiable?

AIM: The purpose of this study was to define and compare the radiation dose s to patients undergoing computed tomography (CT) or intravenous urography (TW) for the investigation of renal colic. METHODS: The IVU dose was calculated from dose area product measurements fo r 27 abdominal films (AXR) and a review of 30 IVUs performed to investigate renal colic, The effective dose to a patient undergoing CT was calculated using anthropomorphic model data. Fifty patients underwent CT for the inves tigation of renal colic over a 6-week period. RESULTS: CT following our protocol confers an average effective dose of 4.7 mSv. An IVU to investigate renal colic used 2.5 AXRs, A 3 film IVU gives a n average dose of 1.5 mSv. Forty-two CT examinations were abnormal and the findings are described in the text. CONCLUSION: Although unenhanced CT confers diagnostic advantages and avoids the risks of intravenous contrast medium, this should be considered agains t the increased radiation dose to the patient which in our institution is o ver three times that of an IVU.