Photon beam attenuation characteristics of three commercial radiation therapy treatment couch-tops
Bibliographic record
Abstract
Abstract Aim The purpose of the study was to investigate the detailed angularly dependent attenuation characteristics of three different commercial couch-tops: Varian IGRT, Qfix kVue Standard and Qfix kVue Dose Max couch-tops used in radiation therapy. Materials and methods The attenuation of photon beams by the treatment couch-tops was measured using a farmer chamber inserted at the centre of a 16 cm diameter cylindrical acrylic phantom for five different photon energies: 6 MV, 6FFF MV, 10 MV, 10FFF MV and 15 MV photon beams. The Varian IGRT couch-top has three different thicknesses thus attenuation measurements were done at the three different longitudinal locations. Measurements were made with the sliding support rails of the Qfix kVue Standard and Qfix kVue Dose Max couch-tops at both ‘rails-in’ and ‘rails-out’ positions. All measurements were taken for several projections through 360° movement of the gantry and for two different field sizes; 5×5 cm2 and 10×10 cm2. Results and findings The results indicate that the maximum attenuation of the Varian IGRT couch-top at the thin, medium and thick portions are 5·1, 5·7 and 8·9%, respectively, the Qfix kVue Standard couch with the rails-in and rails-out are 11·2 and 13·7%, respectively, and Qfix kVue Dose Max couch-top with rails-in and rails-out are 9·7 and 13·8%, respectively. The results from this study can be used to account for the couch-top attenuation during radiation treatment planning of patients treated with these couch-tops.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".