Amber, glad to hear your dad is doing better. A 50% plus reduction is very good. Especially for just 3 weeks. By the time my chemo/rad was done, my tumor in the lymph node was destroyed and all of the cancer was gone. Hope your dad will have the same result. Don't know about the brachytherapy, but it sounds like the med team knows what they are doing for your dad. Maybe another member of the site will be able to answer your questions.