Development and characterization of a prototype selenium‐75 high dose rate brachytherapy source
Bibliographic record
Abstract
Abstract Background 75 Se ( 120 days, 215 keV) offers advantages over 192 Ir ( 74 days, 360 keV) as a high dose rate brachytherapy source due to its lower gamma energy and longer half‐life. Despite its widespread use in industrial gamma radiography, a 75 Se brachytherapy source has yet to be manufactured. Purpose A novel 75 Se‐based source design with a vanadium diselenide core, titled the SeCure source, was proposed. This study aimed to evaluate the feasibility of this source design for dosimetry and manufacturability purposes and to develop an activated prototype source. Methods The source was modeled and integrated into the Monte Carlo‐based treatment planning system RapidBrachyMCTPS, where its TG‐43U1 parameters, photon spectrum, and broad beam first half‐value layers (HVL 1 ) and tenth‐value layers (TVL 1 ) in lead, tungsten, and concrete were calculated. A prototype source was manufactured, and the vanadium diselenide content of the capsule was verified with neutron radiography. The source was then activated to a nominal activity of mCi at the McMaster Nuclear Reactor. The activity was measured with two separate dose calibrators. Gamma spectroscopy was used to characterize any activated radioactive contaminants in the source, and wipe testing was performed to check for any leakage of 75 Se from the encapsulation. Results The SeCure source's TG‐43U1 parameters were computed, showing that times the activity of 75 Se is required relative to 192 Ir to achieve the same dose rate in water at (1 cm, 90). The mean spectral energy of the source is keV, resulting in reduced first half‐value and tenth‐value layers relative to 192 Ir in attenuating materials. For example, the was reduced from mm to mm in lead, from mm to mm in tungsten, and from mm to mm in concrete. The activated source achieved the desired activity, indicated as mCi and mCi at the end of irradiation on the two dose calibrators. All identified radionuclide contaminants decaying below of the 75 Se activity after 5 days post‐irradiation. Wipe testing only identified radioactive contaminants present in activated titanium, with only mCi of detected 72 h post‐irradiation, indicating that the integrity of the encapsulation was maintained. Conclusions The SeCure design possesses the dosimetric, spectral, and physical properties necessary for a feasible high dose rate brachytherapy source. Next, manufacturing of a high‐activity SeCure source will be pursued.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".