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Figure 5. (A) A low quality therapy planning CT with typically thick slab profile and hence poor through-plane resolution. (B) and (C) illustrate the same volume with linear and spline interpolation, respectively. In this example, the spline interpolation (usually considered to be the best method) actually generates a poorer quality re-sampled image with "ringing" artefacts clearly visible as shown in the magnified image D. Although a technical example, illustrated for clarity, caution is relevant to many filtering and re-sampling functions.
