Dosimetric verification of vmat dose distribution with DELTA4 Phantom

Radiation Oncology, has changed a great deal, undergoing an innovation and technical development; there has been an evolution from conformal radiotherapy techniques (3D-CRT), through advanced modalities like intensity-modulated radiation therapy (IMRT) and next volumetric modulated arc therapy (VMAT). VMAT technique requires a dedicated QA (Quality Assurance) procedure for dosimetric verification of a planned dose distribution to check for the agreement between a dose distribution calculated by the Treatment Planning System (TPS) and the corresponding measured dose distribution. Since November 2010, in Radiation Therapy Department of “V. Fazzi ” hospital in Lecce (Italy), 257 patients were treated with VMAT and the corresponding dose distribution were verified with the Delta4® diode array phantom. Parameters used in the comparison between calculated e measured dose are the dose agreement (DA), the distance to agreement (DTA) and the J-index. The phantom measurements closely match the planned dose distributions in high and low dose-gradient region