Adaptive Radiation Therapy for Men With Intermediate- or High-Risk Prostate Cancer

The goal of this clinical trial is to evaluate if adaptive stereotactic body radiation therapy (SBRT) is a safe and effective way to treat prostate cancer in adults. It will assess the safety profile of adaptive SBRT over time. The main questions this trial aims to answer are: * What is highest dose of adaptive SBRT without causing serious side effects? * Can adaptive SBRT more precisely targeting the prostate while reducing radiation exposure to nearby organs? * What side effects do participants experience during treatment, right after treatment, and over the five years post-treatment? * Can adaptive SBRT reduce urination-related side effects and support quality of life during and after treatment? Participants will: * Receive adaptive SBRT treatment every other day, for a total of 5 treatment sessions (called fractions). The full course of treatment typically takes 2 to 3 weeks. * Have a follow-up phone call about 6 weeks after treatment to check on side effects and overall wellbeing. * Visit the clinic for check-ups and tests: * At 90 days (about 3 months) after treatment * Then every 3 months for the first year * Then every 6 months after that