| Computing volumes of abdominal soft organs such as liver, spleen, etc. is important in clinical diagnosis. Splenic injury is the most common soft organ injury seen in Level 1 trauma centers, most often resulting from blunt abdominal trauma sustained in motor vehicle collisions. For soft organ volumetry, different imaging techniques such as Ultrasonography (US), Computed Tomography (CT), and Magnetic Resonance (MR) imaging have been used, all of which have been performed by using different measurement techniques and yield variable results. Cross-sectional imaging used for volumetric assessment requires applications of mathematical algorithms for segmentation involving manual or automated segmentation of the organs of interest. In this thesis CT images are used and a new kind of snake model that permits the snake model to start far from the object, in our case the spleen and yet still draws it towards the object, and forces it into boundary concavities. The proposed snake model is based on a new type of external force field, called gradient vector flow (GVF) which is computed as a spatial diffusion of the gradient of an edge map derived from the image. This computation causes diffuse forces to exist far from the object, and crisp force vectors near the edges. Volumetric information about abdominal organs is not routinely generated for clinical use mainly because accurate, reliable, and operationally practical segmentation algorithms are not readily available. Our system has focused on reliable segmentation of the spleen and computation of its volume. |
