Dosimetric Comparison between Two Dose Calculation Algorithms in SBRT Treatment of Lung Cancer in Ring-based and C-arm Radiation Therapy Equipment

Abstract

Aim: The purpose of this study is to compare the dosimetric differences between two dose calculation algorithms-Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) - in Stereotactic Body Radiation Therapy (SBRT) for lung cancer using Halcyon and TrueBeam radiation therapy (RT) equipment, and to identify the optimal combination for treatment.
Materials and Methods: A Retrospective study which recruited 20 patients with peripherally located primary lung cancer or lung metastasis in the upper or middle lobes treated with SBRT at Kiang Wu Hospital, Macau (KWH) was conducted. CT images were imported into the Varian Eclipse Treatment Planning System (TPS) version 17.01 for re-planning using AAA and AXB in RT equipment. The plan quality and organs at risk (OARs) criteria were assessed based on Radiation Therapy Oncology Group (RTOG)-0813 and RTOG-0915 protocols. Also, Monitor Unit (MU), Beam on Time (BOT), and dose calculation time were recorded for evaluating treatment planning and delivery efficiency. Statistical significance was determined with p-values < 0.05.
Results: AAA provided better conformity, heterogeneity, and R50% than AXB (0.91 vs 0.89, 0.075 vs 0.096, 1.05 vs1.07, respectively, p < 0.05). Both calculation algorithms and RT equipment provided comparable dose to OARs. Notably, compared to Halcyon, TrueBeam required fewer MUs (65.1 vs 58.7, respectively, p < 0.05) to deliver the same dose, and TrueBeam with GPU-based AXB demonstrated advantages in reducing the dose calculation time (p < 0.001).
Conclusion: Both dose calculation algorithms and RT equipment are effective in SBRT lung cancer treatment, offering high precision in target coverage while comparable dose to OARs. TrueBeam with GPU-based AXB is notably efficient in RT treatment planning and delivery.