To determine if functional MRI methods will aid planning of a radiation dose boost within the prostate in patients with prostate cancer potentially improving safety and efficacy.

Inclusion Criteria:

• Hormone therapy naive patients planned to be treated by radical radiotherapy after 3-6 months of androgen suppression
• Patients with low-high risk histologically confirmed localised disease are eligible, with WHO performance status 0-1.

Exclusion Criteria:

• Patients unsuitable for functional MRI of the prostate or gold seed fiducial marker insertion (e.g. patients unable to tolerate endorectal MRI examination).
• No prior pelvic radiotherapy or radical prostatectomy, previous androgen therapy, patients unsuitable for radical radiotherapy, life expectancy <10 years, previous active malignancy within last 5 years, co-morbid conditions likely to impact on the advisability of radical radiotherapy, full anticoagulation, other exclusions to MRI (e.g. hip prosthesis or fixation, claustrophobia, ferromagnetic implants).