The ASPIRE study is a Phase III randomized, single-center study designed to evaluate whether adaptive stereotactic body radiotherapy (SBRT) offers superior clinical benefits compared to standard image-guided SBRT for patients with localized prostate cancer. It aims to explore whether adaptive SBRT can improve urinary outcomes while maintaining effective cancer control. This interventional study is randomized, single-institution, and includes 320 participants with localized prostate cancer. Patients will be stratified based on fractionation schedules (5 vs. 7 fractions), use of rectal spacers, androgen deprivation therapy (ADT), and baseline alpha receptor antagonist use. Participants will be randomized to receive either adaptive SBRT or standard image-guided SBRT, with both arms adhering to established dosing protocols. Inclusion criteria includes an age greater than 18 years, diagnosed with localized prostate adenocarcinoma, and an ECOG performance status of 0-1, Eligible for prostate SBRT. The exclusion criteria includes patients who plan for elective nodal irradiation and contraindications to radiotherapy or MRI (for MR-Linac patients).