Development of a novel ArcCHECK<sup>™</sup> insert for routine quality assurance of VMAT delivery including dose calculation with inhomogeneities
Bibliographic record
Abstract
PURPOSE: To design a versatile, nonhomogeneous insert for the dose verification phantom ArcCHECK(™) (Sun Nuclear Corp., FL) and to demonstrate its usefulness for the verification of dose distributions in inhomogeneous media. As an example, we demonstrate it can be used clinically for routine quality assurance of two volumetric modulated arc therapy (VMAT) systems for lung stereotactic body radiation therapy (SBRT): SmartArc(®) (Pinnacle(3), Philips Radiation Oncology Systems, Fitchburg, WI) and RapidArc(®) (Eclipse(™), Varian Medical Systems, Palo Alto, CA). METHODS: The cylindrical detector array ArcCHECK(™) has a retractable homogeneous acrylic insert. In this work, we designed and manufactured a customized heterogeneous insert with densities that simulate soft tissue, lung, bone, and air. The insert offers several possible heterogeneity configurations and multiple locations for point dose measurements. SmartArc(®) and RapidArc(®) plans for lung SBRT were generated and copied to ArcCHECK(™) for each inhomogeneity configuration. Dose delivery was done on a Varian 2100 ix linac. The evaluation of dose distributions was based on gamma analysis of the diode measurements and point doses measurements at different positions near the inhomogeneities. RESULTS: The insert was successfully manufactured and tested with different measurements of VMAT plans. Dose distributions measured with the homogeneous insert showed gamma passing rates similar to our clinical results (∼99%) for both treatment-planning systems. Using nonhomogeneous inserts decreased the passing rates by up to 3.6% in the examples studied. Overall, SmartArc(®) plans showed better gamma passing rates for nonhomogeneous measurements. The discrepancy between calculated and measured point doses was increased up to 6.5% for the nonhomogeneous insert depending on the inhomogeneity configuration and measurement location. SmartArc(®) and RapidArc(®) plans had similar plan quality but RapidArc(®) plans had significantly higher monitor units (up to 70%). CONCLUSIONS: A versatile, nonhomogeneous insert was developed for ArcCHECK(™) for an easy and quick evaluation of dose calculations with nonhomogeneous media and for comparison of different treatment planning systems. The device was tested for SmartArc(®) and RapidArc(®) plans for lung SBRT, showing the uncertainties of dose calculations with inhomogeneities. The new insert combines the convenience of the ArcCHECK(™) and the possibility of assessing dose distributions in inhomogeneous media.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".