Detection of urolithiasis using low-dose CT : a noise simulation study

How does an acquisition at reduced doses using automatic tube current modulation techniques compare to the normal standard dose CT? Does it affect the sensitivity for detection of calcifications? CT raw data of 54 patients with suspected urolithiasis acquired with automatic tube current modulation techniques were used for image noise simulations with 100%, 50% and 25% dose simulated. Data were analyzed by independent readers with regard to the presence of urolithiasis, stone location, size, density and differential diagnoses. The mean effective dose per standard examination/50%/25% simulation was 7.3 mSv/3.8 mSv/1.9 mSv. Sensitivities/specificities for detection of urolithiasis were calculated for all dose simulations and resulted in 0.94/0.98 in the 50% dose level group and 0.82/0.97 in the 25% dose level group. Low-dose CT with tube current modulation can be used as a standard procedure for the evaluation of patients with suspected acute renal colic.