BACKGROUND: In suspected community-acquired pneumonia (CAP), chest CT is superior to the routinely obtained radiographs (CXR), but administers higher radiation doses. However, ultra-low-dose CT (ULDCT) has shown promising results.

PURPOSE: To compare radiation dose and image quality using standard and ULDCT protocols designed for a multicenter study encompassing three CT scanner models from GE, Canon, and Siemens.

MATERIAL AND METHODS: Patients with suspected CAP were referred for non-contrast standard dose chest CT (NCCT) and ULDCT. Effective radiation dose and Contrast-to-Noise Ratio (CNR) was calculated.

RESULTS: Mean effective doses were GE (n = 10) 6.93 mSv in NCCT and 0.27 mSv in ULDCT; Canon (n = 9) 3.48 in mSv NCCT and 1.11 mSv in ULDCT; Siemens (n = 10) 2.85 mSv in NCCT and 0.45 mSv in ULDCT. CNR was reduced by 29-39% in ULDCT.

CONCLUSION: The proposed CT protocols yielded dose reductions of 96%, 68%, and 84% using a GE, Canon, and Siemens scanner, respectively.