Functional MRI Use in Prostate Radiation Treatment Planning

Inclusion Criteria: * Age 18 or older * Male * Biopsy proven prostate cancer without evidence of metastatic disease * Planned definitive external beam RT with daily ERB and implanted Visicoil fiducial markers. * Prior fMRI-ec documenting an IPL 25 mm2 in axial bidimensional diameter product, concordant with intraprostatic tumor location as documented on transrectal ultrasoundbiopsy * Subject capable of giving informed consent for standard external beam RT and for the study. * No current contraindication that would prevent MRI or gadolinium contrast. Exclusion Criteria: * Metastatic disease * Lack of fMRI-ec documeneting an IPL 25 mm2 in axial bidimensional product, concordant with intraprostatic tumor location as documented on transrectal untrasound biopsy * Neoadjuvant androgen deprivation therapy greater than 10 weeks, defined from date of LHRH analog injection to date of fMRI-sim * Contraindication that would prevent MRI or gadolinium contrast * GFR 30 mL/min/1.73m2 per Crockoft-Gault formula.