Prostate cancer patient undergoing a transrectal ultrasound scan. The scan is being performed to guide the injection of a hydrogel that will be placed between the prostate gland and the wall of the rectum. The hydrogel acts a spacer, protecting surrounding tissue as the patient undergoes radiation therapy. The gel is naturally absorbed by the body after around six months. The prostate is a small gland found just below the bladder surrounding the urethra, the tube urine passes through. Prostate cancer is most prevalent in men over 50 years of age.