Efficient spectral data reduction for accurate iodine quantification in multi-energy CT

This study proposes a spectral data reduction method for multi-channel computed tomography (CT) that optimizes material decomposition accuracy while minimizing data complexity. Spectral CT enables quantitative assessments by utilizing multiple spectral channels, yet the associated noise and computational demands can limit its clinical application. We introduce a weighting scheme that reduces acquired four spectral channels-derived from a dual-layer, rapid kVp-switching (kVp-S) CT setup-into two optimized input channels for material decomposition. This scheme minimizes noise in iodine and water decomposition tasks by optimizing weights based on the Cramer-Rao lower bound. We modeled various duty cycles and patient sizes and compared results to full four-channel and traditional kVp-S configurations. The two-input weighting schemes showed consistently low estimated noise performance within 0.27% difference to the ideal, four-input material decomposition results for all tested duty cycles in a standard adult-sized 300 mm water phantom. In the pediatric (150 mm) and large adult (400 mm) phantom cases, the two-input weighted schemes were within 1% difference of the ideal four-input noise estimator results on average across all tested duty cycles. This study shows that optimized two-channel weighting in spectral CT matches the accuracy of four-channel setups for material decomposition, reducing noise and computational demands.