Introduction: In dual-energy cone-beam computed tomography (CBCT), structures with different X-ray absorption properties at different energy spectra are better depicted. In the case of breast microcalcifications, such a technique can lead to an accurate characterization of Type I and Type II microcalcifications, which indicates malignancy. The emergence of photon counting detectors has made dual-energy applications possible at low patient doses. CBCT detector technology relies on cesium iodine (CsI) scintillator. Materials of higher effective atomic number (Z_eff), density, and scintillation efficiency than CsI crystals could help in dense breast imaging. This study investigates whether material properties could improve image quality in dual-energy breast CBCT imaging.

Methodology: A micro-CBCT system was simulated in GATE, accompanied with seven different detector material schemes: CsI, bismutium germanate (BGO), lutetium oxyorthosilicate (LSO), lutetium–yttrium oxyorthosilicate (LYSO), GAGG, lanthanum bromide (LaBr₃), and CZT, followed by the same electronic processing set up. Dual-energy methodology was applied to 25keV and 40keV.

Four breast phantoms, containing microcalcifications of Type I (CaCO₃ and CaC₂O₄) and Type II (HAp, hydroxyapatite), were imaged under monoenergetic and polyenergetic conditions. Planar images and tomographic data, reconstructed with filtered backprojection (FBP) and ordered subset expectation maximization (OSEM) algorithm, were used. CNR was calculated for each configuration for every microcalcification present.

Results: HAp-CNR values were the highest since they present the highest physical and electronic density. CZT and GAGG average relative CNR values were 1.17 and 1.15 for the monoenergetic application, and 1.08 and 1.03 for the polyenergetic model, respectively, in relation to HAp detection.

Conclusions: Detector material selection plays a crucial role in dual-energy CBCT. Both CZT and GAGG materials present a 3–17% increase in HAp-CNR values in comparison to CsI. These materials present superior stopping power, energy resolution, and light yield, and are an excellent alternative to a CsI scintillator.