Poster — Thur Eve — 37: Improved clustering MLC leaf‐sequencing algorithm for step‐and‐shoot IMRT
Bibliographic record
Abstract
This study examines how to reduce the complexity of fluence map generated using an improved clustering leaf-sequencing method, and evaluates such method in step-and-shoot intensity-modulated radiotherapy (IMRT). Based on the current equal-space grouping algorithm for multileaf collimator (MLC) leaf sequence, we proposed an improved K-means grouping algorithm which can replace the stratification routine in the program of existing leaf sequence. The improved algorithm can be thought of as a gradient descent procedure, which begins at starting cluster centroids, and iteratively updates these centroids to decrease the objective function. The K-means always converge to a local minimum depending on the starting cluster centroids. The K-means algorithm continuously updates cluster centroids until the local minimum is reached. We compare the leaf-sequencing results in term of numerical values from the improved K-means and equal-space grouping algorithm. A representative 1D intensity map from a clinical treatment plan was investigated and optimized by the K-means and equal-space grouping algorithm. It was found that the K-means algorithm decreased the dose square error from 53.67 to 35.27. Moreover, the normalized square differences of the equal-space and K-means algorithm are equal to 2881 and 1244, respectively. The results demonstrated an improvement in accuracy achievable by allowing the fluence map to be defined in an optimal way rather than using the pre-defined criteria. Therefore, the K-means leaf-sequencing algorithm can better simulate the distributions of the input fluence data compared to the traditional grouping algorithm in step-and-shoot IMRT.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.002 |
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".