Keywords:
Lung, Radioprotection / Radiation dose, Digital radiography, Diagnostic procedure
Authors:
M. Mirzai, C. E. Meltzer, B. Gottfridsson, R. R. Norrlund, J. D. Vikgren, �. A. Johnsson, M. Båth, A. Svalkvist; Gothenburg/SE
DOI:
10.26044/ecr2019/C-3400
Conclusion
The results of this study indicate that the reproduction of structures of interest in a chest tomosynthesis examination is significantly reduced at a dose level corresponding to 50% of the original dose.
The fact that the reproduction of the central structures in mediastinum (trachea,
carina and main bronchi) and the retrocardiac part of aorta descendens was most affected by the dose reduction may be due to the presence of high density structures in close proximity,
which causes a high level of noise in the central region of the images (Fig. 4).
This would also explain why peripheral small sized vessels superior to the diaphragmatic dome both anteriorly and posteriorly had slightly higher AUCVGC values than small sized vessels below the highest diaphragmatic point.
In observer performance studies image quality could be assessed in terms of detection of pathology or reproduction of normal anatomical structures.
In studies investigating the detectability of pulmonary mycobacterial disease and pulmonary nodules in CTS it has been shown that the detection rate appears to be unaffected by dose reduction [8,
10,
11].
For example,
Asplund et al [10] performed a study aiming at investigating the effect of dose reduction on nodule detectability.
The CTS examinations included in the study were originally collected at a dose level corresponding to the same original dose level as the CTS examinations included in the present study (0.13 mSv).
The results in the study by Asplund et al showed no significant difference in detection of nodules at dose levels of 32,
50 and 70% of the original dose.
However,
in the present study where the effect of a 50% dose reduction on the perceived reproduction of normal anatomical structures was evaluated,
a significant reduction of perceived image quality was found.
Hence,
even though the detectability of pathology seems to be unaffected by a 50% dose reduction the overall perceived image quality is significantly degraded.