Purpose: The purpose is to evaluate the scatter, dose, and effective detective quantum efficiency (DQE) performance of a slot-scan digital chest radiography system compared wit that of a full-field digital radiography system.
Materials and Methods: Scatter fraction of a slot-scan system was measured for an anthropornorphic and a geometric phantom by using a posterior beam-technique at 117 and 140 kVp. Measurements were repeated with a full-field digital radiography system with and without a 13:1 antiscatter grid at 120 and 140 kVp. For both systems, the effective dose was measured on posteroanterior and lateral views for standard clinical techniques by using dosimeters embedded in a female phantom. The effective DQEs of the two systems were assessed by taking into account the scatter performance and the DQE of each system. The statistical significance of all the comparative differences was ascertained by means of t test analysis.
Results: The slot-scan system and the full-field system with grid yielded scatter fractions of 0.13-0.14 and 0.42-0.48 in the lungs and 0.30-0.43 and 0.69-0.78 in the mediastinum, respectively. The sum of the effective doses for posteroanterior and lateral views for the slot-scan system was 34% lower than that for the full-field system at their respective clinical peak voltages. The effective DQE of the slot-scan system was equivalent to that of the full-field system in the lung region, but was 37% higher in the dense regions.
Conclusion: The slot-scan design leads to marked scatter reduction compared with the more conventional full-field geometries with a grid. The improved scatter performance of a slot-scan geometry can effectively empensate for low DQE and lead to improved image quality.
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