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Erschienen in:
02.01.2019 | Original Article
Radiation dose reduction using two orthogonal topograms associated with automatic tube voltage selection for lung CT scanning as compared with a single anteroposterior topogram
Erschienen in: Japanese Journal of Radiology | Ausgabe 4/2019
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Objective
To evaluate the effectiveness of two orthogonal topograms on radiation dose and image quality (IQ) associated with topogram-based automatic tube voltage selection (ATVS) for lung CT scanning.
Methods
Thirty-seven patients were enrolled in this study. At baseline, only an anteroposterior topogram was obtained and at follow-up, both anteroposterior and lateral topograms were performed. ATVS was turned on during all scans. Objective and subjective IQ evaluations were performed and compared; tube voltage and radiation dose of each scan were noted and analyzed.
Results
A significant difference was observed regarding the objective parameters between baseline and follow-up only in image noise and signal–noise ratio (SNR) in the upper one-third of the image (image noise: 7.49 ± 1.08 vs. 9.10 ± 1.13, p < 0.001; SNR: 4.08 ± 0.87 vs. 3.37 ± 0.63, p < 0.001). No differences were found between baseline and follow-up in the subjective assessment of IQ. The radiation dose was significantly lower at follow-up than that at baseline (2.73 ± 0.83 mSv vs. 3.55 ± 1.24 mSv, respectively; p < 0.001).
Conclusions
Using two orthogonal topograms associated with ATVS could significantly reduce the total radiation dose for lung CT scanning, while subjective IQ was maintained.