A brachytherapy treatment device includes an insertion member, an expandable chamber, and first and second immiscible fluids. The insertion member has proximal and distal ends. The expandable chamber is disposed on the distal end of the insertion member and has an inner surface defining a three-dimensional volume. First and second immiscible fluids are disposed within the expandable chamber and have different radiation absorption properties. At least one of the first and second immiscible fluids forms a fluid radiation shield having a predetermined orientation within the three-dimensional volume. First and second immiscible fluids may have different densities and utilize fluid buoyancy to form an symmetric fluid radiation shield to create an asymmetric radiation dosing profile relative to an inner boundary of a treatment site. Methods for performing brachytherapy treatment include positioning fluids and/or a patient to form an asymmetric fluid radiation shield in a desired orientation to protect sensitive tissues.
