MRI-guided Stereotactic Body Radiotherapy (SBRT) With Simultaneous Integrated Boost for Prostate Cancer

Prostate SBRT is a standard of care treatment for prostate cancer that has not spread to distant metastatic sites. Radiation is delivered to the prostate and seminal vesicles in 5 treatment sessions (fractions). Doses ranging from 35-45 Gy in 5 fractions have demonstrated good outcomes with acceptable toxicity. In this initial study, MRI guided treatment planning and delivery will be used to deliver 7 Gy to the entire prostate and seminal vesicles, with a selective boost of additional 0.5, 1.0, 1.5, or 2 Gy per fraction for a total dose of 37.5, 40, 42.5 or 45 Gy to biopsy-proven lesions, defined using MRI. Hypothesis: MRI-guided treatment planning and delivery can selectively target high-risk prostate nodules and deliver a higher radiation dose, to achieve maximal local control without increasing treatment toxicity