Dosimetric effects of the custom dose iteration times on stereotactic radiotherapy for lung cancer

Abstract

PurposeTo evaluate the dosimetric effects of the custom dose iteration function in the Monaco 6.0 planning system on stereotactic radiotherapy for lung cancer. MethodsUsing the custom dose iterative function segment shape optimization (SSO) times in the Monaco 6.0 treatment planning system, the iterative times were set as 3, 5, 8, 10, and 12, respectively. Five volumetric modulated arc stereotactic body radiation therapy (SBRT) plans were made for each patient, and other optimization parameters and optimization functions were kept consistent. The dose volume histogram (DVH) statistical table was used to evaluate the dose of the target area and organs at risk (OAR). Statistical analysis was performed using SPSS 25 software, and the results were statistically different when p < 0.05. ResultsFor the target area dose analysis, SSO8, SSO10, and SSO12 groups showed similar results, significantly better than both SSO3 and SSO5 groups (p < 0.05). With the increase in the times of SSO, the protection of the heart was better, except for SSO3, the maximum dose of the esophagus and V47Gy of great vessels were significantly lower than SSO5 in all groups. The mean dose of heart was significantly lower in SSO10 and SSO12 than SSO5 (p < 0.05). There was no significant difference in other OAR among the groups. The optimization time (OT) of each group was statistically different, the maximum OT exceeded 1000s, the maximum deviation between groups exceeded 600s, and the OT increased significantly with the times of SSO (p < 0.05). There was no statistically significant difference between the 5 groups of monitor unit (MU), and segment was not significantly different between the groups except SSO3 which was significantly higher than SSO5 (p < 0.05). The delivery time (DT) was statistically different between the groups except for SSO3. ConclusionsIn the treatment of left-sided lung cancer patients with volumetric modulated arc SBRT, considering both calculation accuracy and clinical treatment efficiency, SSO times of 8 is recommended for designing SBRT for lung cancer with the Monaco treatment planning system.