Monte Carlo simulations of dose near a nonradioactive gold seed
Bibliographic record
Abstract
The relative doses and hot/cold spot positions around a non-radioactive gold seed, irradiated by a 6 or 18 MV photon beam in water, were calculated using Monte Carlo simulation. Phase space files of 6 and 18 MV photon beams with a field size of 1 x 1 cm2 were generated by a Varian 21 EX linear accelerator using the EGSnrc and BEAMnrc code. The seed (1.2 x 1.2 x 3.2 mm3) was positioned at the isocenter in a water phantom (20 x 20 x 20 cm2) with source-to-axis distance = 100 cm. For the single beam geometry, the relative doses (normalized to the dose at 5 mm distance above the isocenter) at the upstream seed surface were calculated to be 1.64 and 1.56 for the 6 and 18 MV beams respectively when the central beam axis (CAX) is parallel to the width of the seed. These doses were slightly higher than those (1.58 and 1.52 for 6 and 18 MV beams respectively) calculated when the CAX is perpendicular to the width of the seed. Compared to the relative dose profiles with the same beam geometry without the seed in the water phantom, the presence of the seed affects the dose distribution at about 3 mm distance beyond both the upstream and downstream seed surface. For a pair of opposing beams with equal and unequal beam weight, the hot and cold spots of both opposing beams were mixed. For a 360 degree photon arc around the longitudinal axis of the seed, the relative dose profile along the width of the seed was similar to that of the opposing beam pair, except the former geometry has a larger dose gradient near the seed surface. In this study, selected results from our simulation were compared to previous measurements using film dosimetry.
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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".