I did a bit of searching, but I could not confirm that med-travel page's
statement that Ac255 therapies have gained FDA approval. If it hasn't been approved yet, a clinical trial would be a way to gain early access.
Ac255 trials are listed at
clinicaltrials.gov. Search there for "prostate cancer" in the the Condition box and "Ac225" in Other Terms (I tried linking the search result here, but the link didn't work.) I see trials in the U.S. and Germany.
See
here for research at City of Hope.
If you do a literature
search, you'll see recent papers on the topic. You can see the names of those conducting research and where they are located. You could try writing to the corresponding authors for up-to-date information.
It does look quite promising!
Djin