Translating FLASH to the clinic: treatment planning system for a FLASH-compatible dose delivery using a novel x-ray UHDR machine
Bibliographic record
Abstract
Abstract Objective. To develop and validate a treatment planning system (TPS) for a novel x-ray ultra-high dose rate (UHDR) system and compare its performance with conventional volumetric modulated arc therapy (VMAT). Approach. A TPS was developed for a novel x-ray UHDR system featuring stationary beamlines and a Scanning Pencil-beam High-speed Intensity-modulated x-ray source (SPHINX). We studied an exemplary case using 16 beam angles, 1D scanning perpendicular to the bore axis, and a linear accelerator operating at 12 MeV electron energy with 1 mA average beam current. Treatment plans were generated using various system configurations and compared with clinical VMAT plans for lung (PTV: 239 cm 3 ), brain (PTV: 372 cm 3 ), and head-and-neck (PTV: 55 cm 3 ) cases. Configurations included different beamlet widths for lung cancer, coplanar and conical beam arrangements for brain cancer, and different beamlet spacings for head-and-neck cancer. Dose distributions in terms of target conformity and homogeneity indices, local dose rates (LDR), local irradiation time (LIT), and organ-at-risk (OAR) sparing were compared. A validation workflow combining Monte Carlo simulations with TPS-generated treatment parameters was developed and tested on a lung case to ensure TPS dose calculation accuracy. Main results. TPS-generated plans achieved comparable target coverage to VMAT while delivering significantly higher dose rates ( ⩾ 12.5 Gy/s vs. 0.03 Gy/s) and ultra-short LITs. However, UHDR plans in general showed increased OAR mean doses. Conical beam arrangements in the brain case yielded higher maximum LDRs at isocenter of up to 49 Gy/s with LITs as low as 37 ms, but increased integral dose. The head-and-neck case demonstrated high LDRs (62 Gy/s to 98% of PTV) within 20 ms, with minimal differences between beamlet spacing configurations. The lung case validation workflow demonstrated ⩾ 98 % 3D γ-index pass rate using 3 % / 3 mm threshold, confirming plan accuracy. Significance. The developed UHDR-TPS enables treatment planning for a novel x-ray UHDR system. In this preliminary study, it achieved plan quality comparable to VMAT for the specific lung, brain, and head-and-neck cancer cases studied, while delivering significantly higher dose rates and shorter irradiation times. Further optimization of the UHDR delivery with x-rays is needed, however, to decrease OAR doses and validate these initial findings.
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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 | 0.001 | 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 | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.017 | 0.003 |
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".