ArticleJournal of applied clinical medical physics2022
Insensitivity of machine log files to MLC leaf backlash and effect of MLC backlash on clinical dynamic MLC motion: An experimental investigation.
Article in Journal of applied clinical medical physics, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers.
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Who cites it
10 citing papers in PubMed, 15 citations in OpenAlex.
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- Patient-specific quality assurance for extremely small field sizes using 3D in vivo dosimetry in fractionated stereotactic radiosurgery for brain metastases.Journal of applied clinical medical physics · 2026Article
- Comparison of log file-based and measurement-based QA for detecting MLC positional errors and evaluating dosimetric impacts of MLC defects.Journal of applied clinical medical physics · 2025Article
- A pathway away from measurement-based patient-specific QA: A review of contemporary quality assurance for external-beam radiotherapy sub-systems.Journal of applied clinical medical physics · 2025Review
- Evaluation of the TrueBeam machine-performance-check (MPC): Collimator device check (CDC).Journal of applied clinical medical physics · 2025Article
- Evaluation of an improved picket fence style test for routine MLC positional QA.Journal of applied clinical medical physics · 2025Article
- A novel EPID-based MLC QA method with log files achieving submillimeter accuracy.Journal of applied clinical medical physics · 2024Article
- Insensitivity of machine log files to MLC leaf backlash and effect of MLC backlash on clinical dynamic MLC motion: An experimental investigation.Journal of applied clinical medical physics · 2022Article
- Optimizing Patient-specific Quality Assurance Workload with Neural Network Analysis of Log Files and Complexity Indices.Journal of medical physicsArticle
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Authors and funding
7 authors at 3 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeMulti-leaf-collimator (MLC) leaf position accuracy is important for accurate dynamic radiotherapy treatment plan delivery. Machine log files have become widely utilized for quality assurance (QA) of such dynamic treatments. The primary aim is to test the sensitivity of machine log files in comparison to electronic portal imaging device (EPID)-based measurements to MLC position errors caused by leaf backlash. The secondary aim is to investigate the effect of MLC leaf backlash on MLC leaf motion during clinical dynamic plan delivery.
methodsThe sensitivity of machine log files and two EPID-based measurements were assessed via a controlled experiment, whereby the length of the "T" section of a series of 12 MLC leaf T-nuts in a Varian Millennium MLC for a Trilogy C-series type linac was reduced by sandpapering the top of the "T" to introduce backlash. The built-in machine MLC leaf backlash test as well as measurements for two EPID-based dynamic MLC positional tests along with log files were recorded pre- and post-T-nut modification. All methods were investigated for sensitivity to the T-nut change by assessing the effect on measured MLC leaf positions. A reduced version of the experiment was repeated on a TrueBeam type linac with Millennium MLC.
resultsNo significant differences before and after T-nut modification were detected in any of the log file data. Both EPID methods demonstrated sensitivity to the introduced change at approximately the expected magnitude with a strong dependence observed with gantry angle. EPID-based data showed MLC positional error in agreement with the micrometer measured T-nut length change to 0.07 ± 0.05 mm (1 SD) using the departmental routine QA test. Backlash results were consistent between linac types.
conclusionMachine log files appear insensitive to MLC position errors caused by MLC leaf backlash introduced via the T-nut. The effect of backlash on clinical MLC motions is heavily gantry angle dependent.
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