Fillers and methods for displacing tissues to improve radiological outcomes

A method of delivering a therapeutic dose of radiation to a patient comprising:

• (i) injecting anesthesia and (ii) injecting saline to expand the space between the first and second tissue location, wherein the first tissue location is associated with the rectum and the second tissue location is associated with the prostate gland and introducing a biocompatible, biodegradable filler device between the first tissue location and the second tissue location to increase a distance between the first tissue location and the second tissue location, said biocompatible, biodegradable filler being collagen and introducing collagen into Denovillier's space and treating the second tissue location with a therapeutic dose of radiation, said therapeutic dose of radiation being 70 to 100 Gy, so that the presence of the filler device causes the first tissue location to receive less than 50% of the dose of radioactivity compared to the amount of the dose of radioactivity the first tissue location would have received in the absence of the filler device, wherein the filler device is removed by biodegradation of the filler device in the patient.