For such disappeared sites, web.archive.org is very useful. The more chance that a site has been linked to, the more chance is that you will find it in the archive there. That means probably 99% or more of all disappeared ImageJ related sites can be found in the archive, as they have been linked to via the main ImageJ sites. Links to external sites (download links) also usually work as they are archived too (unless they were generated on the fly by an interactive script).
Anyway, the most recent copy if the Tudor DICOM page is from Feb. 2019:
BTW, I tried the Tudor DICOM library but found it of little value as the most important tags for me were not saved. But as a basis for further development on your own, the code found on the DICOM site is very useful.