Independent monitor unit verification for treatment planning system used in radiotherapy

Independent MU verification is one of the methods for patient based quality control. This study was carried out at the Akdeniz University Faculty of Science Department of Physics and was aimed to perform acceptance and commissioning "XIO Standalone" independent MU verification software in CMS XIO TPS. For acceptance tests the square open fields, asymmetric open fields and wedged filter fields was created in the TPS. Than the calculated dose from "XIO Standalone" was compared with obtained dose from TPS and measured dose by IBA blue phantom2 water phantom. The calculated dose from "XIO Standalone" was comparable with measured dose and calculated dose from TPS. Later, six-field conformal plans were generated for 6 and 15 MV photon beams for IBA I'mRT phantom. The dose was calculated for each beam in "XIO Standalone". The dose of each beam was measured by FC65-P ion chamber and I'mRT phantom. The calculated dose from "XIO Standalone" didn't accordance with measured dose and calculated dose from TPS for beams that located under the treatment table. The iBeam Evo ready model table top was added in a created plan to eliminate this difference. The electron density value of table top compositions was entered into the system. Table top was included to outer contour for calculation in XIO. Recalculation was made with same MU in TPS. Then MU verification was made in "XIO Standalone" again. The measured doses and calculated doses from TPS were consistent after the table was added in the system. However, "XIO Standalone" according to measurement dose difference increased because Standalone hasn't inhomogeneity correction. The solution to this problem has been produced and the action levels were determined for clinical use.