Evaluation of the feasibility of log file-based three-dimensional independent dose verification system in quality assurance of intensity-modulated radiation therapy / 中华放射肿瘤学杂志

ABSTRACT

Objective To assess the feasibility of the log file-based three-dimensional independent dose verification system for the quality assurance of clinical radiotherapy.Methods The statistical values of the percentage depth dose,off-axis curves and output factor calculated by the Mobius system were statistically compared with the measured data by three-dimensional water tank.The three-dimensional independent dose verification in clinical radiotherapy plan and the acceleratr log file-based three-dimensional dose verification during the treatment were performed in 17 patients with nasopharyngeal cancer.The accuracy of dose calculation and reconstruction of Mobius system was assessed.A statistical analysis was performed on the intra-fractionalγpass rate (3％/3 mm) for each patient to evaluate the stability of intra-fractional radiotherapy.Results The percentage depth dose,off-axis curve and output factor statistically calculated by the Mobius system matched well with the data measured by three-dimensional water tank.The dose-volume histogram (DVH) parameters between the target area and organ at risk during clinical radiotherapy plan were statistically compared in 17 patients with nasopharyngeal cancer.The maximum deviation was-2.16％ for the three-dimensional independent dose verification in the clinical radiotherapy plan,and 0.18 Gy for the accelerator log file-based three-dimensional dose verification.The averageγpass rate for 17 nasopharyngeal cancer patients was 99.26％,and the maximum deviation of intra-fractional radiotherapy was below 0.5％.Conclusions The function of dose reconstruction and independent calculation of the Mobius system yeilds the same accuracy with the treatment planning system,which can quickly perform three-dimensional independent dose verification in the clinical radiotherapy plan and accelerator log file-based three-dimensional dose verification throughout the treatment,thereby guarantting and providing the safe and reliable technical support for clinical treatment.