On the capabilities of conventional x‐ray tubes to deliver ultra‐high (FLASH) dose rates
Bibliographic record
Abstract
PURPOSE: By means of Monte Carlo (MC) simulations and indirect measurements, we have evaluated the maximum dose rates achievable with conventional x-ray tubes and related them to FLASH therapy dose rates of >40 Gy/s. METHODS: Monte Carlo models of two 160 kV x-ray tubes, the 3-kW MXR-160/22 and the 6-kW MXR-165, were built in the EGSnrc/BEAMnrc code. The dose rate in a water phantom placed against the x-ray tube surface, located at 3.7 and 3.5 cm from the focal spot for the MXR-160/22 and MXR-165 x-ray tube, respectively, was calculated with DOSXYZnrc. Dose delivered with the 120-kV beam in a plastic water phantom for the MXR-160/22 was measured and calculated. Gafchromic EBT3 films were placed at 15 and 18 mm depths in the plastic water phantom that was irradiated with a low tube current of 0.2 mA for 30 s. RESULTS: The maximum 160-kV phantom surface dose rate was determined to be FLASH capable, calculated as (114.3 ± 0.6) Gy/s and (160.0 ± 0.8) Gy/s for the MXR-160/22 and MXR-165 x-ray tubes, respectively. The dose rate in a 1-cm diameter region was found to be (110.6 ± 2.8) Gy/s and (151.9 ± 2.6) Gy/s and remained FLASH capable to depths of 1.4 and 2.0 mm for the MXR-160/22 and MXR-165 x-ray tube, respectively. The 120-kV dose profiles measured with EBT3 films agreed with MC simulations to within 3.6% for regions outside of heel effect and at both measurement depths; this presented a good validation data set for the simulations of phantom surface dose rate using the 160-kV beam. CONCLUSIONS: We have indirectly determined that, with a careful experimental design, conventional x-ray tubes can be made suitable for use in FLASH radiotherapy and dosimetry experiments.
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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) | 0.004 | 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".