Conventional or moderately hypo-fractionated radiation therapy are the current standard of care treatment options for men receiving post-prostatectomy radiation therapy. These treatment regimens typically span 4-8 weeks, representing a high burden of therapy, which may result in decreased utilization of salvage radiotherapy, the only potentially curable treatment for men with relapsed disease following prostatectomy. Ultra-hypofractionated radiation therapy (also known as stereotactic body radiation therapy \[SBRT\]) would decrease the total number of treatments to 5, delivered over 2 weeks, which would greatly reduce treatment burden.