Evaluation of Tumor Control Based on Serial Multiparametric MRI and Post-Treatment Biopsies For Patients Treated With Dose Intensification to the Dominant Intra-Prostatic Lesion (DIL) Using Ultra-Hypofractionated, MR-Guided Radiotherapy

The purpose of this study is to assess the impact of this MR-guided radiotherapy on tumor control of the dominant intraprostatic lesion among patients with intermediate risk prostate cancer. This study of Radiotherapy to the Prostate and Dominant Lesion Using Ultra-Hypofractionated, MR-adaptive Radiation Therapy aims to evaluate tumor control after definitive ultra-hypofractionated external beam radiation therapy (including a simultaneously delivered high-dose boost to a dominant lesion as detected on prostate magnetic resonance imaging (MRI)) in patients with intermediate-risk prostate cancer. This will incorporate the use of multiparametric MRI for target segmentation and the use of the MR-linac with adaptive radiation planning to treat the prostate gland, incorporating a dose boost to the dominant intraprostatic lesion (DIL) that is visible on T2-weighted and diffusion-weighted imaging and de-escalation of dose to the remainder of the prostate.