Figure 1
From: Histogram-derived modified thresholds for coronary artery calcium scoring with lower tube voltage
Histogram matching using the cumulative distribution function to obtain modified thresholds for 100 kV. The 120 kV histogram showed CT numbers of 130 HU through 1887 HU for 260,104 pixels from coronary calcium (a). The 100 kV histogram demonstrated 280,737 pixels with CT numbers from 130 HU to 2059 HU (b). The overlapping two histograms (a,b) showed more pixels from 100 kV images (c). After excluding 20,633 pixels (280,737 – 260,104 = 20,633) from the 130 HU of the 100 kV histogram, the two histograms were almost identical (d). Afterwards, we found matching points in the 100 kV histogram.
