Commissioning of Axesse accelerator for volumetric modulated arc therapy / 中华放射肿瘤学杂志

ABSTRACT

Objective To test the accuracy and reliability of Axesse accelerator for volumetric modulated arc therapy (VMAT).Methods The accuracy and reliability of Axesse accelerator for VMAT were tested in a stepwise manner, from the simple to the complex and from the part to the whole.For the parts of the system, the stability of dosimetric output and the position accuracy of multi-leaf collimator (MLC) were tested.For the process of the system, the variable VMAT dose rates and gantry speed modulation, the MLC speed and dose rate modulation, and dosimetric verification in patients were tested.Results Compared with fixed gantry irradiation, the variation in dosimetric output was below 1.0% for rotary irradiation including the slide rotary irradiation of the dynamic MLC.The MLC position error of 0.5 mm was visible using the electronic portal imaging system of Axesse, iViewGT 3.40.The MLC position accuracy was within 1 mm for fixed gantry irradiation and rotary irradiation.In the range of the dose rate applied in clinical practice, the testing results of variable VMAT dose rates and gantry speeds as well as variable dose rates and MLC speeds showed that the variation between different strip-field beam intensities was below 2.0%.Using a gamma criterion of 3 mm/3%, the pass rates in dosimetric verification of patients with cervical cancer, prostate cancer, and breast cancer were 96.52%, 95.72%, and 98.83%, respectively.Conclusions The Axesse system can precisely control MLC motion, variable dose rates, and gantry speeds in VMAT.The Axesse system is accurate and reliable for VMAT.