A balloon applicator for an intraoperative radiation therapy system includes an x-ray beam shaping component for emitting x-rays in a plurality of possible directions in three dimensions. The balloon applicator includes connecting structure for connecting to the intraoperative radiation therapy system and an inflatable balloon contactor having an outer surface. The balloon applicator has a beam hardening system including a beam hardening compound disposed between the x-ray beam shaping component and the outer surface of the balloon. The beam hardening system is capable of hardening the beam in beam directions in three dimensions. An intraoperative radiation therapy system and a method for conducting intraoperative radiation therapy are also disclosed.