Optimization of exposure parameters in full field digital mammography

Area of Science:

• Medical Physics
• Radiological Imaging
• Diagnostic Imaging

Background:

• Digital mammography requires careful optimization of exposure parameters to maximize image quality and minimize radiation dose.
• Balancing signal-to-noise ratio (SNR) and patient dose is crucial for effective mammographic screening.
• Previous studies have investigated these parameters, but updates are needed for current systems.

Purpose of the Study:

• To compare the impact of technique factors on image SNR and radiation dose across major commercial full-field digital mammography (FFDM) systems.
• To evaluate how breast thickness and tissue type influence the optimization of exposure parameters.
• To assess the performance of automatic exposure control (AEC) in achieving optimal exposure settings.

Main Methods:

• A phantom study was conducted using five commercial FFDM systems (GE Healthcare, Siemens, Hologic, Fischer, Fuji).
• Performance was evaluated using various x-ray target/filter combinations and nine phantom types representing different breast thicknesses and compositions.
• The figure of merit (FOM) used was the ratio of squared image SNR to mean glandular dose, and AEC performance was also assessed.

Main Results:

• The figure of merit (FOM) was generally a slow function of kVp but strongly dependent on the target/filter combination.
• Higher tube voltages (kVp) did not consistently improve performance and sometimes decreased FOM.
• Optimal exposure parameters were system-specific, influenced by available target/filter combinations and detector type.

Conclusions:

• The choice of target/filter combination is more critical than kVp for optimizing FFDM performance.
• While AEC systems generally performed well, there is room for improvement in their ability to select optimal exposure parameters.
• System-specific optimization is necessary for achieving the best balance between image quality and patient dose in digital mammography.