Comparison of volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) plannings for the treatment of left sided breast and regional lymphatic tissue AIP Conference Proceedings 1747, 060002 (2016) Abstract. The purpose of this research is to clinically evaluate the performance of a novel reference chamber (Stealth Chamber by IBA). Experimental data were acquired in water with IBA three-dimensional (3D) blue phantom 2 . Percent depth dose (PDD) comparisons for fields ranging from 1×1 to 25×25 cm 2 were performed for photon energies of 6 and 15 MV. Profile comparison for fields ranging from 1×1 to 25×25 cm 2 were executed for the depths of dmax, 5, 10 and 20 cm. PDD curves and dose profiles obtained from measurements with the Stealth Chamber and the CC13 as the reference chamber were compared to each other for field sizes ranging from 1×1 to 25×25 cm 2 for 6 and 15 MV. Experimental results from this investigation indicate the benefits associated with chamber positioning and time expended during the acquisition of the relative measurements of PDDs and profiles for the beam commissioning of photon beams when the Stealth Chamber is used as a reference chamber to perform these tasks.