This study is a pilot study of 60 patients look at the toxicities, biochemical and patient reported quality of life outcomes of an MR-integrated focal boost using HDR prostate brachytherapy. Eligible patients for this study will be determined by pre-brachytherapy MRI (DCE, T2 weighted and diffusion weighted) imaging, to identify a dominant intraprostatic lesion. The HDR dose prescription is 19 Gy to the whole gland ad 22.5 Gy to MRI visible lesion delivered in one fraction, assuming that dose constraints to critical organs can be met.