SU‐E‐T‐411: Monte Carlo Simulations for Quality Assurance of Varian TrueBeam 10XFFF VMAT SABR Treatments
Bibliographic record
Abstract
Purpose: To establish feasibility of performing quality assurance on 10X Flattening Filter Free (FFF) VMAT stereotactic ablative radiotherapy (SABR) treatments on the TrueBeam LINAC with Monte Carlo simulations using vendor‐supplied phase space data. Methods: Monte Carlo simulations were performed with BEAMnrc and DOSXYZnrc using the TrueBeam 10XFFF photon beam phase space data that were made available by the Varian Monte Carlo research team. To establish validity of the phase space, dose calculations in a water phantom for fields ranging from 2×2 cm2 to 40×40 cm2 were performed using DOSXYZnrc. Percent depth doses (PDDs), transverse profiles and output factors were calculated and compared with measurements for all the fields simulated. Monte Carlo simulations of 10XFFF SABR VMAT plans were performed on a homogeneous cylindrical phantom and on the Quasar™ phantom with a lung‐equivalent insert. Simulations were compared with both ion chamber measurement and Eclipse Treatment Planning System (TPS) dose calculations. 3D gamma analysis comparing Monte Carlo and TPS results was performed. Results: Monte Carlo simulations and measured values agreed within 1% and 2% for PDDs and profiles respectively. The agreement between measured and calculated output factors was within 1% including for highly asymmetric fields. These results indicate that the 10XFFF phase space data is sufficiently accurate for use in simulations for quality assurance purposes in radiation therapy. For the VMAT plans the point dose agreement between MC and both measured and TPS calculations was within 1.2%. The 3%, 3mm Gamma test pass rates were 95% and 92% for plans calculated on the homogeneous phantom and on the Quasar phantom respectively. Conclusion: We have demonstrated the feasibility of performing patient specific quality assurance on 10XFFF SABR treatment plans using Monte Carlo simulations of the TrueBeam LINAC. This is the first independent validation on the 10XFFF Varian phase space data presented to date. The work of Tony Teke, Cheryl Duzenli and Ermais Gete has been supported by Varian under a Master Research Agreement.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".