A system for immobilization of a patient body part for radiotherapy applications which includes a device having at least one flanged support member which is suitable to be mounted to a fixation surface and is adapted to receive and retain at least two sheets is described. The first sheet covers the anatomical contours of a first area of the body part, and the second sheet covers the anatomical contours of a second area of the body part which is not covered by the first sheet. The system is capable of supporting the immobilized body part free from the fixation surface by the two sheets and the device.