The effect of dynamic range and gain on B-mode images of the phantom artery. This figure shows a series of B-mode images taken from a single scan of Phantom C at a distance of 20 mm from the probe. The same region of interest was analysed to show the effect of varying dynamic range and gain settings on the appearance of the B-mode image and also on the detected interfaces. The diagram of a cross-section of a phantom artery shows how the leading edges of the near and far wall echo lines represent the interface between the agar compound and the water surrounding the artery. 1. Leading edge of near wall water-agar interface. 2. Leading edge of near wall agar-water interface. 3. Leading edge of far wall water-agar interface. 4. Leading edge of far wall agar-water interface.