Semi-Automatic Image Segmentation for Volumetric Visualization of Pelvis CT Scan-Images. The currentdevelopment of computerized tomography (CT) has enable us to obtain cross sectional image using multi slicingtechniques in an order of few seconds. The obtained images represent several tissue structures on cross section slicebeing imaged. One challenge to help diagnosis using CT images is extracting an anatomic structure of interest using amethod of image segmentation and volumetric visualization with the assistance of computers. In case of volumetricvisualization of pelvis bones extracted from multi-slice CT images, whole images which are containing part of pelvisbone structures must be segmented. In this research, an image segmentation technique based on active contour isimplemented for semi-automatic multi slice image segmentation. Image segmentation steps are initialized with a definemodel of 2D curve on the first slice image manually. Next, its model curve is deformed to reach the final result of 2Dcurve that fits to boundary edges of pelvis bone image. The final result of 2D curve on previous slice image was used asan initialization model of 2D curve on the next slice images. This process will continue until the final slice image. Thissegmentation method was compared with the segmentation method based on threshold from homogenous intensitydistribution and manual segmentation method. Quantitative analysis from the results of segmentation on each slice andqualitative analysis on the representation of volumetric visualization are performed in this research.