To improve radiation therapy of prostate cancer, the investigators must be able to accurately identify the tumour. By using advanced functional imaging techniques available on state-of-the-art MRI scanners to clearly show the specific location of the tumour inside the prostate, the investigators can use advanced radiation therapy techniques to specifically target the tumor and control it with as few radiotherapy clinic visits as possible. This is different than current techniques which treat the whole prostate gland to the same dose, delivered over 7-8 weeks of daily radiotherapy visits. By increasing the radiation dose to the active tumor while still maintaining adequate radiation dose to the rest of the prostate, the investigators hope to better control prostate cancer and reduce complications to nearby normal tissues.