Example of heuristic validation of mass conservation for Incept-net outputs in porcine scan. Left subfigure: low-threshold (i.e. [25, 140] keV) CT image from coronal plane. Right subfigure: pixel-wise weighted sum of mass densities (eq. (5)) across all material maps acquired from the same coronal plane (display window: [0, 2]). The method for calculating the weighted sum is described in Sec. 2.4. The mean value of the weighted sum of mass densities at the three region-of-interests (ROIs #1 – 3, radius 11, 16, and 8 mm) was 1.04 (±0.01), 1.03 (±0.01), and 1.02 (±0.01), respectively. The range of display window for CT images was [-160, 240] HU.