SU-F-T-573: Evaluation of EBT-XD Radiochromic Films for Verification of SBRT and SRS Treatment Delivery
Bibliographic record
Abstract
Purpose: To evaluate the accuracy and precision of radiochromic films EBT-XD for quality control of stereotaxic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) plan delivery. Methods: A film cut in 3×10 cm2 strips was irradiated from 0 to 20 Gy in increments of 1 to 1.5 Gy using a 15 MeV electron beam. Triple-channel film calibration was completed 24 hours later by scanning the film strips on an Epson 10000XL scanner using a well-defined protocol. Several dose measurements of increasing complexity were subsequently performed with Varian iX accelerators. Pieces of films were first irradiated in a solid water phantom with 6 MV photon beams and a static gantry to doses spanning the calibration range, either in a single field or multiple fields setup. High dose (>15 Gy per fraction) IMRT plans were then measured. Finally films were irradiated with volumetric modulated arc therapy (VMAT) plans of lung and spinal lesions with prescribed doses per fraction between 8 and 20 Gy. The dose measured with the films was compared to the calculated dose from the Eclipse planning system using the Anisotropic Analytical Algorithm (AAA). Results: 77 dose measurements were compared to either ion chamber measurements or dose calculations (reference). The average dose difference between film measurements and reference was 0.7 % and the standard deviation was 1.3%. The maximum and minimum dose differences were +3.5% and −2% in the 4 Gy to 20 Gy range. Measured dose profiles of lung and vertebra treatment plans agreed very well with the calculations. Conclusion: EBT-XD films are a useful dosimeter for quality control of SBRT and SRS plan delivery. The measurement of a full 2D dose plane with high spatial resolution and acceptable dose accuracy make it an advantageous choice compared to other detectors such as ion chambers or diodes.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".