Low-dose computed tomography of the paranasal sinuses: radiation doses and reliability analysis

PURPOSE: The study aimed to (1) optimize the radiation doses of computed tomography (CT) of paranasal sinuses, (2) compare the radiation doses of different CT protocols with that of plain radiography, and (3) evaluate the reliability of low-dose CT in the detection of pathology and characterization of the detected pathology. MATERIALS AND METHODS: A head phantom was examined with different scan parameters to define a cutoff value to which the radiation dose can be reduced without negative impact on image quality. Kruskal-Wallis test and Wilcoxon W test were performed to compare the effective doses of the plain radiography in 30 patients with that of 3 different CT protocols in a total of 90 patients. The interobserver and intraobserver agreement in the detection of pathologic findings and in characterization of the pathology was estimated by calculating kappa value. RESULTS: The effective doses of plain radiography and low-dose CT were 0.098 and 0.045 mSv, respectively (P < .001). The effective dose of standard CT of sinuses (0.371 mSv) was 3.8 times higher than that of plain radiography and 8.2 times higher than that of low-dose CT (P < .001). The interobserver and intraobserver agreement on CT with regard to detection of pathology and pathology characterization was almost perfect (kappa values 0.81-1) compared to fair (kappa values 0.38-0.39) in plain radiography. CONCLUSIONS: The here proposed low-dose CT means significant dose reduction and is a reliable method in the investigation of the paranasal sinuses. (Less)