Aeskulap is a medical image viewer.
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iPath is providing a free and open platform for "case based collaboration", especially designed for medical applications (telemedicine, etc). The iPath-Server package provides a sort of medical BBS to discuss/consult cases online. Additional modules are available.
Horos™ is a free, open source medical image viewer. The goal of the Horos Project is to develop a fully functional, 64-bit medical image viewer for OS X. Horos is based upon OsiriX and other open source medical imaging libraries. Horos is made available under the GNU Lesser General Public License, Version 3 (LGPL-3.0).
With high performance and an intuitive interactive user interface, OsiriX MD is the most widely used DICOM viewer in the world. It is the result of more than 10 years of research and development in digital imaging. It fully supports the DICOM standard for an easy integration in your workflow environment and an open platform for development of processing tools. It offers advanced post-processing techniques in 2D and 3D, exclusive innovative technique for 3D and 4D navigation and a complete integration with any PACS.