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