OsiriX is an open-source software designed for navigating and displaying multidimensional DICOM images, particularly useful for interpreting large datasets from combined PET-CT studies. Developed in Objective-C on a Macintosh platform using the GNUstep environment, it leverages OpenGL for fast 3D graphics and integrates open-source libraries like ITK and VTK for image processing and rendering. The software features an intuitive user interface, allowing users to customize tools and functions, and supports dynamic series, image fusion, and 3D visualization. It is freely available under the GNU license at http://homepage.mac.com/rossetantoine/osirix. The software addresses the challenges posed by the rapid evolution of digital imaging techniques and the increasing complexity of multidimensional and multimodality studies. Traditional 2D viewers are inadequate for interpreting large datasets from modern imaging modalities like PET-CT and Cardiac CT. OsiriX enables efficient navigation through large image sets without requiring high-end hardware, utilizing open-source components for flexibility and adaptability. It supports real-time 3D rendering, multiplanar reformatting, and volume rendering, and allows users to interactively navigate through multiple dimensions, including time and function. The software integrates various open-source toolkits, including VTK for 3D image processing, ITK for medical image processing, and DICOM Offis for network functions. It also supports DICOM file management, multimedia file formats, and grid computing for enhanced performance. OsiriX's user-friendly interface allows customization for different user needs, and it is designed to take advantage of multiprocessor systems and grid computing technologies for improved performance. OsiriX is a versatile tool that enables radiologists and clinicians to efficiently interpret complex diagnostic studies using standard personal computers. Its open-source nature and integration of advanced technologies make it a valuable resource for medical imaging applications. The software is freely available and continuously updated, ensuring it remains a powerful and adaptable solution for multidimensional image navigation and visualization.OsiriX is an open-source software designed for navigating and displaying multidimensional DICOM images, particularly useful for interpreting large datasets from combined PET-CT studies. Developed in Objective-C on a Macintosh platform using the GNUstep environment, it leverages OpenGL for fast 3D graphics and integrates open-source libraries like ITK and VTK for image processing and rendering. The software features an intuitive user interface, allowing users to customize tools and functions, and supports dynamic series, image fusion, and 3D visualization. It is freely available under the GNU license at http://homepage.mac.com/rossetantoine/osirix. The software addresses the challenges posed by the rapid evolution of digital imaging techniques and the increasing complexity of multidimensional and multimodality studies. Traditional 2D viewers are inadequate for interpreting large datasets from modern imaging modalities like PET-CT and Cardiac CT. OsiriX enables efficient navigation through large image sets without requiring high-end hardware, utilizing open-source components for flexibility and adaptability. It supports real-time 3D rendering, multiplanar reformatting, and volume rendering, and allows users to interactively navigate through multiple dimensions, including time and function. The software integrates various open-source toolkits, including VTK for 3D image processing, ITK for medical image processing, and DICOM Offis for network functions. It also supports DICOM file management, multimedia file formats, and grid computing for enhanced performance. OsiriX's user-friendly interface allows customization for different user needs, and it is designed to take advantage of multiprocessor systems and grid computing technologies for improved performance. OsiriX is a versatile tool that enables radiologists and clinicians to efficiently interpret complex diagnostic studies using standard personal computers. Its open-source nature and integration of advanced technologies make it a valuable resource for medical imaging applications. The software is freely available and continuously updated, ensuring it remains a powerful and adaptable solution for multidimensional image navigation and visualization.