Author: Yijian Cao, Jenghwa Chang, Lyu Huang 👨🔬
Affiliation: Northwell, Hofstra University Medical Physics Program 🌍
Purpose: This study evaluates the treatment delivery efficiency and workflow of two advanced linear accelerator systems—Varian’s TrueBeam (C-arm) and Halcyon (O-ring)—for prostate Stereotactic Body Radiation Therapy (SBRT).
Methods: A retrospective analysis of 60 prostate SBRT treatments was conducted at our institution, including patients treated with TrueBeam STX or Halcyon 4.0. Each of 12 patients received a prescribed dose of 40 Gy across five fractions. Parameters such as planning target volumes (PTVs), total monitor units (MUs), image-to-treat time, beam-on time, and total treatment time were extracted from ARIA 16.01 treatment records. The unpaired Student’s t-test was employed to compare metrics.
Results: The analysis revealed comparable planning target volumes between the two systems (TrueBeam: 105.1±22.3 cc; Halcyon: 92.4±14.4 cc). While Halcyon exhibited slightly higher total MUs (3096.6±457.2) compared to TrueBeam (2936.5±296.9), beam-on times were similar (TrueBeam: 3.36±0.94 min; Halcyon: 3.54±0.89 min), attributed to Halcyon's faster mechanical motions that compensates for its lower dose rate. However, Halcyon demonstrated superior efficiency in image-to-treat time, averaging 5.9 minutes, significantly outpacing TrueBeam’s 18.2 minutes. This disparity stems from workflow variations, with the TrueBeam system employing a kv-kv pair prior to Cone Beam Computed Tomography (CBCT), while the Halcyon system utilizes solely CBCT alongside a 'one-step' patient setup approach. This resulted in a notable reduction in total treatment time (Halcyon: 9.4±4.8 min; TrueBeam: 21.5±18 min; p<0.05).
Conclusion: This comparison highlights Halcyon’s superior efficiency in delivering prostate SBRT, enabling higher patient throughput within standard work hours. While findings are limited to a single institution, they provide valuable insights for clinical decision-making. Future research will expand the dataset and evaluate system performance across additional modalities and treatment sites.