SU‐E‐T‐787: Utility of the Two Candidate 192‐Ir and 169‐Yb HDR Sources for Use with a Novel Direction Modulated Brachytherapy Tandem Applicator for Cervical Cancer Treatment
Bibliographic record
Abstract
Purpose: A novel tungsten alloy shielded, MRI‐compatible, direction modulated brachytherapy (DMBT) concept tandem applicator, which enables unprecedented intensity modulation, was used to evaluate treatment plan quality improvement over a conventional tandem. The utility of the 192‐Ir and 169‐Yb HDR sources, for use with the DMBT applicator, was evaluated. Methods: The total diameter of the DMBT tandem applicator is 6.0 mm, which consists of 5.4‐mm diameter tungsten alloy and 0.3 mm thick plastic sheath. The tandem has 6 symmetric peripheral 1.3‐mm diameter grooves for the source to travel. MCNPX v.2.6 was used to simulate the 192‐Ir and 169‐Yb sources inside the DMBT applicator. First, TG‐43 source parameters were evaluated. Second, 3D dose matrix with 1 mm3 resolution were imported into an in‐house‐coded inverse optimization treatment planning program to obtain optimal plans for 19 clinical cases. All plans were compared with the standard tandem and ring plans. Prescription dose was 15.0 Gy. All plans were normalized to receive the same HRCTV D90. Results: Generally, the DMBT tandem (and ring) plans were better than the conventional tandem and ring plans for 192‐Ir and 169‐Yb HDR sources. The mean data of D2cc for bladder, rectum, and sigmoid were 11.65±2.30 Gy, 7.47±3.05 Gy, and 9.84±2.48 Gy for Ir‐192 DMBT tandem, respectively. These data for Yb‐169 were 11.67±2.26 Gy, 7.44±3.02 Gy, and 9.83±2.38 Gy, respectively. The HR‐CTV D98 and V100 were 16.37±1.86 Gy and 97.37 ± 1.92 Gy for Ir‐192 DMBT, respectively. The corresponding values for Yb‐169 were 16.43±1.86 Gy, and 97.51 ± 1.91 Gy. Plans with the 169‐Yb source generally produced more favorable results where V100 increased by 13.65% while D2cc across all OARs reduced by 0.54% compared with the 192‐Ir plans. Conclusion: For the DMBT tandem applicator, 169‐Yb source seems to produce more directional beams resulting in increased intensity modulation capacity, thus resulting in more conformal plans
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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 | 0.000 |
| 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) | 0.001 | 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".