Investigation of mechanical and dosimetric quality assurance of volumetric modulated arc therapy/intensity modulated radiotherapy devices with arccheck

This study will be carried out on the Varian Trilogy iX 120-MLC linear accelerator which is capable of performing IMRT (Intensity Modulated Radiotherapy), VMAT (Volume-tric Modulated Arc Therapy) and SBRT (Stereotactic Body Radiotherapy) in the Department of Radiation Oncology at Recep Tayyip Erdoğan University Training and Research Hospital.When the quality assurance tests and the mechanical controls of the linear accelerator are not performed correctly and precisely, the probability of tumor control may be reduced and the healthy tissues in the proximity of a tumor volume may take a higher dose. In order to avoid such adverse events, quality assur-ance tests in line with international protocols are mandatory in our country. In our study, without any other dosimetric equipment, IMRT/VMAT patient specific QA and mechanical and dosimetric QAs will be performed with a single dosimetric equipment. ArcCHECK® will be dosimetrically and mechanically compared with different models and types of dosimetric equipment e.g. Water Phantom, EPID, and Gafchromik Film and thus investigate to take many of these measurements with ArcCHECK®. The results of the study indicated that the mechanical QA tests of linacs can be performed with ArcCHECK® dosimetric system. The tests of isocenter verifica-tion, gantry angles, dose profiles and MLC/JAWs were carried out with Arc-CHECK®. All the measurements were also taken with water phantom and Gaf-Chromic films. The superiority of ArcCHECK® system to the other systems with respect to time, repeatability and sensitivity was observed. However, in the position verification tests of MLC/JAWs, ArcCHECK® was found to be inadequate because of lack of a single MLC leaf position data. Our results showed that ArcCHECK® can be used for the tests of dosimetric and mechanical QA in the clinics with high work-load.