Welcome to Health Care Magic ..
I read your query and it seems that your father has been diagnosed with prostate cancer
one year ago , and underwent radiation
You can ask your Doctor that your fathers prostate cancer is in which stage .
Blood in urine is not only due to plavix
which is rare complication to manifest but advanced prostate cancer will have typical symptom of Blood in urine.
Therefore I suggest you to start treatment for your father by radiotheraphy or surgery in ealier as prostate cancer is treatable if found earlier.
Hope this information helps you.
Thanks & Take Care.