Two Fraction Prostate SBRT With DIL SIB

Inclusion Criteria: * Patient age greater than or equal 18 * Localized adenocarcinoma of the prostate * Biopsy-proven diagnosis of prostate adenocarcinoma * Low to intermediate risk National Comprehensive Cancer Network (NCCN) disease * TX-T2c-8th addition staging * PSA\<20 ng/ml * Grade group 3 or less * Proper rectal space replacement required as determined by the treating radiation oncologist * Prostate size less than 60cc defined at time of simulation based on MRI * Patient ability to undergo MRI and documented dominant Prostate Imaging Reporting and Data System (PI-RADS) 3 or higher lesion \-- Exception is very low risk, low risk, or favorable intermediate risk with a low to intermediate decipher score in which case an SIB is not utilized * Androgen-deprivation therapy (ADT) is left to the discretion of the treating radiation oncologist * Agreement to use effective contraceptive methods such as condoms and spermicidal foam, intrauterine device, or for their partner to use prescription birth control pills * Ability to give informed consent Exclusion Criteria: * High risk disease * Pelvic lymph node involvement * Prophylactic lymph node irradiation requirement as determined by the treating radiation oncologist * Evidence of clinical or radiological extracapsular extension or seminal vesicle invasion * Prior radiation to the pelvis * Prior malignancies within the last 5 years * Inability to meet pre-specified 2 fraction DVH constraints * Prostate size \> 60cc as measures at treatment planning MRI * Active significant inflammatory bowel disease (IBD) or rheumatological disease * Prior prostate surgeries * Previous uro lift * Transurethral resection of the prostate (TURP) within 6 months of SBRT * "Reasonable" urinary, bowel, and erectile function as defined by the pre-treatment EPIC questionnaire (\>50 overall summary score for each domain) * Men of reproductive potential may not participate unless they agree to use an effective contraceptive method