Segmentation of medical images with known ground truth is useful for investigating properties of performance metrics and comparing different approaches of combining multiple manual segmentations to establish a reference standard, thereby informing selection of performance metrics and truthing methods. For medical images, however, segmentation ground truth is typically not available. One way of synthesizing segmentation errors is to use regular geometric objects as ground truth, but they lack the complexity and variability of real anatomical objects. To address this problem, we developed a medical image segmentation synthesis (MISS)-tool. The MISS-tool emulates segmentations by adjusting truth masks of anatomical objects extracted from real medical images. We categorized six types of segmentation errors and developed contour transformation tools with a set of user-adjustable parameters to modify the defined truth contours to emulate different types of segmentation errors, thereby generating synthetic segmentations. In a simulation study, we synthesized multiple segmentations to emulate algorithms or observers with pre-defined sets of segmentation errors (e.g., under/over-segmentation) using 220 lung nodule cases from the LIDC lung computed tomography dataset. We verified that the synthetic segmentation results manifest the type of errors that are consistent with our pre-configured setting. Our tool is useful for synthesizing a range of segmentation errors within a clinical segmentation task.
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