DCMTK is a collection of libraries and applications implementing large parts the DICOM standard. It includes software for examining, constructing and converting DICOM image files, handling offline media, sending and receiving images over a network connection, as well as demonstrative image storage and worklist servers. DCMTK is is written in a mixture of ANSI C and C++.
WWW: http://www.dcmtk.org/dcmtk.php.en