A system for monitoring doses from an ionizing radiation source to a treatment region of a patient and immobilizing a body cavity relative to the treatment region, is provided. The system includes a probe body for insertion into the body cavity. The probe body separates the body cavity from the treatment region to reduce exposure to doses from the ionizing radiation source. Radiation detectors are disposed along the probe body to measure at least one dose. A slot disposed adjacent the radiation detectors receives a dosimetry film that, upon exposure to the one or more doses from the ionizing radiation source, indicates a quantification of the doses. A coupling is in fluid communication with a removable sheath having coupled thereto a vacuum or a pump to remove fluid or gas from the body cavity and ensure inner wall of the body cavity is in contact with the sheath.
