The Digital Subtraction Angiography (DSA) technique can be applied to a fluoroscopy series (XA) to allow you to visualize blood vessels better. The pre-contrast image (so-called mask) is subtracted from the subsequent images in which the arteries/veins are filled with the contrast media and, thus, the bony or dense soft-tissue areas are removed from the final image.
1) Open the fluoroscopy series in the viewer.
2) Click on the subtraction button on the toolbar or use the / shortcut to activate the DSA mode.
3) A vertical toolbar displaying additional DSA tools will appear next to the series preview pane.