Poster - Wed Eve-48: An Opposed Matched Beam IMRT Technique for Prostate Cancer Patients with Bilateral Hip Prosthesis
Bibliographic record
Abstract
When intensity modulated radiation therapy (IMRT) is used to treat prostate patients with bilateral metal hip implants, beams which would otherwise be oriented in a lateral direction must be angled toward a posterior direction in order to avoid incidence through the prostheses. This has the undesirable effect of increasing the volume of rectum subtended by these beam, thereby either increasing rectal dose or reducing target coverage. We report a new technique which exploits the use of opposed fields that are asymmetric and matched along a plane that is tangent to the most anterior aspect of the implant on one side and the most posterior aspect of the implant on the other. This geometry allows the posterior beams to be aligned more closely to the lateral directions since the asymmetric beam subtends only the posterior portion of the target. The remaining anterior portion of the target is subtended by the opposed asymmetric beam. Neither beam of the opposed matched pair is incident through an ispilateral prosthesis. IMRT plans were developed for a representative patient using both the conventional and the opposed matched techniques. Analysis of the dose volume histogram indicates better rectal sparing and target coverage by the opposed matched technique. Calculation and measurement of dose at a point along the match line indicates sensitivity to misalignment of 2.5% per mm per beam. Thus, care must be taken to ascertain opposed matched beam alignment and to minimize the time between treating each beam of the opposed matched pair.
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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 | 0.000 | 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) | 0.013 | 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".