Static and rotational step-and-shoot IMRT treatment plans for the prostate: A risk comparison study
Bibliographic record
Abstract
PURPOSE: For certain clinical applications, rotational intensity modulated radiation therapy (R-IMRT) techniques such as volumetric modulated arc therapy (VMAT) are capable of improved target dose coverage and shorter delivery time when compared to static, step-and-shoot IMRT. The authors performed a risk comparison study for two standard step-and-shoot IMRT plans and two step-and-shoot Rotational IMRT plans that were designed specifically for a Siemens Primus linear accelerator. METHODS: CT images of a RANDO phantom were used to generate R-IMRT and static IMRT plans. One simple and one complex prostate cases were created to investigate these techniques. The R-IMRT plans consisted of 72 single-segmented 6 MV beams, equally spaced with beam angle separations of 5°. The static IMRT plans employed seven multisegmented 6 MV beams. Both types of plans were optimized in Pinnacle(3) with the direct machine parameter optimization (DMPO) algorithm using the same set of optimization objectives. The plans were delivered to a RANDO phantom and thermoluminescent diode (TLD) dose measurements were performed at various locations throughout the phantom. Risk coefficients and organ weightings as defined by International Commission on Radiological Protection (ICRP) Publication 103 were used to calculate the resulting effective doses to various organs at risk, as well as the overall risk estimate for both techniques. RESULTS: For the simple prostate case, the R-IMRT technique provided a higher dose to organs at risk within the CT volume and a lower overall peripheral dose to remaining organs. The R-IMRT plan had a risk estimate of 4.56% when compared to the IMRT risk of 4.78%. For the complex prostate case, there was no significant difference in the lifetime risks of the IMRT (5.73%) and R-IMRT (5.74%) plans. CONCLUSIONS: R-IMRT is an approximation to VMAT and it was found that there is no clinically significant difference between lifetime risk estimates between R-IMRT and standard seven-beam IMRT for the prostate.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".