Fast generation of lung SBRT plans with a knowledge-based planning model on ring-mounted Halcyon Linac

Justin Visak, Aaron Webster, Mark E. Bernard, Mahesh Kudrimoti, Marcus E. Randall, Ronald C. McGarry, Damodar Pokhrel

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Purpose: To demonstrate fast treatment planning feasibility of stereotactic body radiation therapy (SBRT) for centrally located lung tumors on Halcyon Linac via a previously validated knowledge-based planning (KBP) model to support offline adaptive radiotherapy. Materials/methods: Twenty previously treated non-coplanar volumetric-modulated arc therapy (VMAT) lung SBRT plans (c-Truebeam) on SBRT-dedicated C-arm Truebeam Linac were selected. Patients received 50 Gy in five fractions. c-Truebeam plans were re-optimized for Halcyon manually (m-Halcyon) and with KBP model (k-Halcyon). Both m-Halcyon and k-Halcyon plans were normalized for identical or better target coverage than clinical c-Truebeam plans and compared for target conformity, dose heterogeneity, dose fall-off, and dose tolerances to the organs-at-risk (OAR). Treatment delivery parameters and planning times were evaluated. Results: k-Halcyon plans were dosimetrically similar or better than m-Halcyon and c-Truebeam plans. k-Halcyon and m-Halcyon plan comparisons are presented with respect to c-Truebeam. Differences in conformity index were statistically insignificant in k-Halcyon and on average 0.02 higher (p = 0.04) in m-Halcyon plans. Gradient index was on average 0.43 (p = 0.006) lower and 0.27 (p = 0.02) higher for k-Halcyon and m-Halcyon, respectively. Maximal dose 2 cm away in any direction from target was statistically insignificant. k-Halcyon increased maximal target dose on average by 2.9 Gy (p < 0.001). Mean lung dose was on average reduced by 0.10 Gy (p = 0.004) in k-Halcyon and increased by 0.14 Gy (p < 0.001) in m-Halcyon plans. k-Halcyon plans lowered bronchial tree dose on average by 1.2 Gy. Beam-on-time (BOT) was increased by 2.85 and 1.67 min, on average for k-Halcyon and m-Halcyon, respectively. k-Halcyon plans were generated in under 30 min compared to estimated dedicated 180 ± 30 min for m-Halcyon or c-Truebeam plan. Conclusion: k-Halcyon plans were generated in under 30 min with excellent plan quality. This adaptable KBP model supports high-volume clinics in the expansion or transfer of lung SBRT patients to Halcyon.

Original languageEnglish
Pages (from-to)54-63
Number of pages10
JournalJournal of Applied Clinical Medical Physics
Issue number11
StatePublished - Nov 2021

Bibliographical note

Publisher Copyright:
© 2021 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine


  • Halcyon Linac
  • KBP model
  • coplanar geometry
  • lung SBRT
  • non-coplanar VMAT

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Radiology Nuclear Medicine and imaging


Dive into the research topics of 'Fast generation of lung SBRT plans with a knowledge-based planning model on ring-mounted Halcyon Linac'. Together they form a unique fingerprint.

Cite this