TU‐A‐301‐01: Microcalcifications Visibility in Cone Beam Breast CT with Various Flat Panel Detectors

Purpose: To investigate the visibility of microcalcifications (MCs) in cone beam breast CT using various flat panel detectors. Methods: We investigated the visibility of MCs in cone beam CT (CBCT) breast imaging using various flat panel detectors, including PaxScan 4030CB (aSi/CsI) by Varian Medical Systems, FPD14 (aSi/aSe) by Anrad, C4742 (CCD/GdO2S:Tb) and C7921 (CMOS/CsI) detectors by Hamamatsu. A paraffin cylinder with a diameter of 135 mm and a thickness of 40 mm was used to simulate a 100% adipose breast. Calcium carbonate grains, from 125 – 140 μm to 224 – 250 μm in various size groups, were used to simulate the MCs. Groups of 25 same size MCs were arranged into 5 × 5 clusters. Each cluster was embedded at the center of a 15 mm diameter cylindrical paraffin phantom, which as inserted into a hole at the center of the breast phantom. The breast phantom with the simulated MCs was scanned on a bench top CBCT system at various exposure levels for each detector. The reconstructed images were reviewed by 6 readers independently. The MC visibility was quantified as the fraction of visible MCs and averaged over all readers for analysis. The visibility was plotted as a function of the estimated dose level and image signal‐to‐noise ratio (SNR) for various scans and detectors. The relative detector DQEs were compared among the four detectors. Results: It was found the relationship between the visibility and size can be fitted with a Boltzmann function for all the detectors. The Varian detector has the best MC visibility among all the detectors at the same dose level. Conclusions: The visibility of MCs increased with the isocenter dose and image SNR for all detectors. Detector with better DQE could achieve the same MC visibility with lower radiation dose. This work was supported in part by grants CA104759, CA13852 and CA1245 85 from NIH‐NCI, a grant EB00117 from NIH‐NIBIB, and a subcontract from NIST‐ATP.