Tumour dose enhancement using modified megavoltage photon beams and contrast media
Bibliographic record
Abstract
This study examines the magnitude of tumour dose enhancement achieved by injection of gadolinium or iodine contrast media (CM) and treatment using modified x-ray photon spectra from linear accelerators. Monte Carlo modelling of the linear accelerator and patient geometry was used to explore the effect of removing the flattening filter for various beam qualities and the resultant effect on dose enhancement. In addition, ionization measurements were conducted to observe dose enhancement within a phantom containing CM. Simulation results indicate that for flattened 6-24 MV photon beams and realistic CM tumour concentrations, the dose enhancement remains below 5%. However, if the flattening filter is removed, dose enhancement is increased significantly. For a 30 mg ml(-1) gadolinium CM tumour concentration, for example, 8.4%, 10.8%, 13.7% and 23.1% dose enhancements are achieved for 18 MV, 6 MV, 4 MV and 2 MV unflattened beams, respectively. In contrast to the phototherapy technique, which uses the orthovoltage beam from a modified CT scanner to achieve dose enhancement, all unflattened spectra preserve the dose build-up at the surface, and thus the skin and bone are spared.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".