Radiotherapy to the Prostate and Dominant Intra-Prostatic Lesion (DIL)

Inclusion Criteria: * Intermediate risk prostate cancer patients will be eligible for this study. Risk groups will be assigned as per NCCN guidelines. Intermediate risk patients will be defined as: * PSA 10-20 ng/ml or * Gleason score = 7 or * Clinical stage T2b/T2c * Additionally, patients will be required to meet the following criteria: * Age \>18 * KPS \> 80 * Prostate size \< 60cc * Presence of a prostatic lesion with maximum dimension of \>/= 0.5cm and no more than two additional disease foci, each with a maximum dimension less than that of the dominant lesion. * International Prostrate Symptom Score \< 15 * Subjects must fill out the standard MRI screening form and satisfy all MRI screening criteria Exclusion Criteria: * Prior androgen deprivation therapy for prostate cancer * Evidence of metastatic disease on bone scan or MRI/CT * MRI ineligibility due to the presence of a cardiac pacemaker, defibrillator or other implanted metallic or electronic device which is considered MR unsafe, severe claustrophobia or inability to lie flat for the duration of the study, etc. * Metallic hip implant, metallic implant or device in the pelvis that might distort the local magnetic field and compromise quality of MP-MRI. * Lateral pelvic separation greater than 50 cm and/or anterior-posterior separation greater than 35 cm which are incompatible with MRCAT reconstruction * Contra-indications to receiving gadolinium contrast * KPS \< 80 * Pelvic MRI or CT (MRI preferred) evidence of radiographic T3, T4 or N1 disease. * Prior history of transurethral resection of the prostate * Prior history of chronic prostatitis * Prior history of urethral stricture * Prior history of pelvic irradiation * History of inflammatory bowel disease * Unable to give informed consent * Unable to complete quality of life questionnaires * Abnormal complete blood count. Any of the following * Platelet count less than 75,000/ml * Hb level less than 10 gm/dl * WBC less than 3.5/ml * Abnormal renal function tests (creatinine \> 1.5)