Eligible patients will have low and intermediate risk prostate cancer with a dominant intraprostatic lesion definable on multi parametric MRI (PIRADS 4 or 5). Patients will have MR planned LDR focal brachytherapy to the DIL using iodine-125, while at the same time have single 19 Gy delivered to the whole prostate using ultrasound directed high dose-rate brachytherapy (HDR). The LDR boost dose will start at 50 Gy, and increase DIL dose in sequential cohorts of patients up until a dose of 80 Gy. Up to 20 patients will be included. Primary endpoint is toxicity at 3 months.
