In-silico study of the impact of system design parameters on microcalcification detection in wide-angle digital breast tomosynthesis.

Abstract

Purpose: Accurate detection of microcalcifications ( $\mu \mathrm{Calcs}$ ) is crucial for the early detection of breast cancer. Some clinical studies have indicated that digital breast tomosynthesis (DBT) systems with a wide angular range have inferior $\mu \mathrm{Calc}$ detectability compared with those with a narrow angular range. This study aims to (1) provide guidance for optimizing wide-angle (WA) DBT for improving $\mu \mathrm{Calcs}$ detectability and (2) prioritize key optimization factors.

Approach: An in-silico DBT pipeline was constructed to evaluate $\mu \mathrm{Calc}$ detectability of a WA DBT system under various imaging conditions: focal spot motion (FSM), angular dose distribution (ADS), detector pixel pitch, and detector electronic noise (EN). Images were simulated using a digital anthropomorphic breast phantom inserted with $120\mu m$ $\mu \mathrm{Calc}$ clusters. Evaluation metrics included the signal-to-noise ratio (SNR) of the filtered channel observer and the area under the receiver operator curve (AUC) of multiple-reader multiple-case analysis.

Results: Results showed that FSM degraded $\mu \mathrm{Calcs}$ sharpness and decreased the SNR and AUC by 5.2% and 1.8%, respectively. Non-uniform ADS increased the SNR by 62.8% and the AUC by 10.2% for filtered backprojection reconstruction with a typical clinical filter setting. When EN decreased from 2000 to 200 electrons, the SNR and AUC increased by 21.6% and 5.0%, respectively. Decreasing the detector pixel pitch from 85 to $50\mu m$ improved the SNR and AUC by 55.6% and 7.5%, respectively. The combined improvement of a $50\mu m$ pixel pitch and EN200 was 89.2% in the SNR and 12.8% in the AUC.

Conclusions: Based on the magnitude of impact, the priority for enhancing $\mu \mathrm{Calc}$ detectability in WA DBT is as follows: (1) utilizing detectors with a small pixel pitch and low EN level, (2) allocating a higher dose to central projections, and (3) reducing FSM. The results from this study can potentially provide guidance for DBT system optimization in the future.