Congress:
EuroSafe Imaging 2020
Keywords:
Performed at one institution, Diagnostic or prognostic study, Retrospective, Infection, Diagnostic procedure, CT, Radioprotection / Radiation dose, Head and neck, Head and Neck
Authors:
B. Petritsch, A. Weng, T. A. Bley, A. Kosmala
DOI:
10.26044/esi2020/ESI-07549
Description of activity and work performed
Paranasal sinus low-dose CT was performed in 120 patients with three protocols (assigend to group 1 - 3):
- Group 1: 192-row DSCT 100 kV, tin-filter, IR [SOMATOM Force, Siemens Healthcare GmbH]
- Group 2: 64-row CT 120 kV, IR [SOMATOM Definition AS, Siemens Healthcare GmbH]
- Group 3: 16-row CT 120 kV, FBP [SOMATOM Sensation, Siemens Healthcare GmbH]
The CT attenuation (in Hounsfield units [HU]) was assessed and signal-to-noise-ratios (SNR) were compared. Subjective image quality was assessed using a five-point Likert-scale: 1 = excellent; 2 = good; 3 = moderate; 4 = fair; 5 = non-diagnostic. The estimation of the effective radiation dose (ED) was based on the volume computed tomography dose index (CTDIvol) and dose length product (DLP). To compensate for the different reference phantom (32-cm CTDI-phantom instead of 16-cm phantom) of the tin-filtered protocol in group 1, a previously published additional conversion factor of 2.5 was applied in our study. The effective dose was calculated with the following formulas:
ED = DLP x 0.0019 mSv x mGy-1 x cm-1 x 2.5 (group 1)
ED = DLP x 0.0019 mSv x mGy-1 x cm-1 (group 2 and 3)
CTDIvol and DLP were significantly lower (1 vs. 2: p<0.01; 1 vs. 3: p<0.01) in group 1 (0.12±0.0 mGy / 2.2±0.2 mGy*cm) compared to group 2 (5.6±0.5 mGy / 74.8±10.8 mGy*cm) and group 3 (8.5±0.2 mGy / 115.2±12.0 mGy*cm). Effective radiation dose was significantly (p<0.01) lower in group 1 (0.005±0.001 mSv) compared to group 2 (0.17±0.02 mSv) and group 3 (0.26±0.03 mSv). Subjective image quality was rated moderate in group 1, and excellent in groups 2 and 3. Thereby a reliable evaluation of inflammatory sinus disease was possible in all patients. SNR was highest in group 1 and lowest in group 3 (1 vs. 2: p<0.01; 1 vs. 3: p<0.05; 2 vs. 3: p<0.01).