A system and method for immobilization of the human breast in a prone
position during imaging and radiotherapy. The system includes a
vacuum-assisted breast immobilization cup comprising two layers joined
together with an air space between. The inner layer has densely
perforated holes while the outer layer is airtight. When a negative
vacuum is applied to the intermediate airspace the breast tissue is
sucked against the mesh wall of the inner layer to preventing sliding. In
addition, the cup assembly is locked into a fixed position against the
patient torso via a body fixture, as well as against the patient support
structure. The established geometric relationship among the cup, chest
wall, imaging/treatment table or couch may be accurately repeated. The
system further includes a three-dimensional localization system to
uniquely place the breast in a coordinate system having fixed geometric
relationship with the breast immobilization cup.