Androgen-responsive POSLUMA-guided Intra-prostatic Boost

Inclusion Criteria: * 18 years of age and older. * Eastern Oncology Group Status 0 to 1.Performance status * Histologic diagnosis of prostate cancer. * Prior screening MRI with at least one PI-RADS4 or PI-RADS 5 lesion, obtained within 180 days of screening. * NCCN intermediate-risk or high-risk prostate cancer (Appendix B). All patients will be staged by MRI. * Prior PSMA PET scan with at least one focal avid lesion greater than background prostate that is concordant with a lesion on MRI, obtained within 180 days of screening. * Intention for SBRT (36.25 Gy/5 fraction) with focal boost (up to 50 Gy) to one MRI/PET-concordant lesion34. Exclusion Criteria: * Prior imaging (CT, bone scan, MRI, PSMA-PET/CT) showing nodal or distant disease. * Intention to receive treatment intensification with secondary androgen receptor signaling inhibitors or chemotherapy. * Clinical T4 disease. * Prior ADT. * Prior pelvic RT. * Prior prostate surgery, including TURP. * International prostate symptom score > 20. * Prior urethral stricture. * Prostate volume > 80 cc on MRI. * Hip implants that cause artifacts over the prostate gland. * Inability to discontinue anti-coagulation for fiducial marker placement. * Active Crohn's disease or scleroderma.