OsiriX is an open-source software designed for navigating and interpreting large sets of multidimensional and multimodality images, such as combined PET-CT studies. Developed in Objective-C on a Macintosh platform using the GNUstep development environment, OsiriX leverages the fast and optimized 3D graphic capabilities of OpenGL. The software features an interactive jog-wheel device for faster navigation and is highly customizable, allowing users to add or remove tools from the toolbar based on their specific needs. It integrates open-source libraries like ITK and VTK for advanced image processing and rendering. OsiriX supports various image manipulation functions, including zoom, pan, intensity adjustment, and filtering, and can handle very large sets of images without pre-loading. The software is designed to be multithreaded, utilizing the parallel processing capabilities of multiprocessor computers, and can potentially benefit from Grid Computing technology for even more efficient processing. OsiriX is freely available under the GNU open-source licensing agreement.OsiriX is an open-source software designed for navigating and interpreting large sets of multidimensional and multimodality images, such as combined PET-CT studies. Developed in Objective-C on a Macintosh platform using the GNUstep development environment, OsiriX leverages the fast and optimized 3D graphic capabilities of OpenGL. The software features an interactive jog-wheel device for faster navigation and is highly customizable, allowing users to add or remove tools from the toolbar based on their specific needs. It integrates open-source libraries like ITK and VTK for advanced image processing and rendering. OsiriX supports various image manipulation functions, including zoom, pan, intensity adjustment, and filtering, and can handle very large sets of images without pre-loading. The software is designed to be multithreaded, utilizing the parallel processing capabilities of multiprocessor computers, and can potentially benefit from Grid Computing technology for even more efficient processing. OsiriX is freely available under the GNU open-source licensing agreement.