Assessment of intra and interfractional organ motion during adjuvant radiochemotherapy in gastric cancer
Bibliographic record
Abstract
15132 Background: Adjuvant combined chemotherapy and radiotherapy (RT) in gastric cancer improves survival, however acute toxicity is substantial. Toxicity may be improved with three-dimensional (3D) RT, but organ motion must be considered in planning target volume (PTV) delineation. Methods: Participants (n=22) had baseline free breathing planning CT (CT0) with BodyFix immobilization. Abdominal CTs in free breathing (FB), inhale (I) and exhale (E) states were obtained in weeks 1, 3 and 5 of RT. Datasets were fused to CT0 in Pinnacle3 6.2 planning system using bone registration. Volumes of interest (VOIs) [right (R) and left (L) kidney, liver, stomach, pancreas, celiac axis and porta hepatis] were contoured and points of interest (POIs) were placed at each centre of mass. POIs were manually placed at the left dome of diaphragm and splenic hilum. Organ motion was determined by the difference between POI positions in cranial-caudal (CC), anterior-posterior (AP) and right-left (RL) directions. Maximal respiratory motion was determined from the difference between I and E positions. Interfractional displacement in organs relative to bones at weeks 1, 3 and 5 was determined on FB scans as compared to baseline. Results: Interfractional organ motion was maximal in CC direction with median absolute displacements (range) in mm of: splenic hilum 10 (0–52), stomach 8 (0.4–27.2), liver 7.4 (0.5–23.6), diaphragm 6 (0–28), L kidney 5.7 (0–37.3), R kidney 5.3 (0.2–35.3), pancreas 5.7 (0.3–29.1), porta hepatis 4 (0–14) and celiac axis 1.7 (0–9.1). Median interfraction displacement (range) in CC, AP and RL in mm for all organs was: 5.7 (0- 52), 2.1 (0–23.1), 2.3 (0–15.9). Positional difference between I and E state (median for all organs) was: 16 mm CC, 5.9 mm AP, and 1.7 mm RL with maximal individual breathing excursions of 59.9, 30.2 and 21.1 mm, respectively. Conclusions: Interfraction organ displacement relative to bones can be quantified and used in the safe design of 3D conformal radiotherapy. Respiratory motion can be substantial in some individuals. Accounting for organ motion in 3D RT planning is necessary and may reduce the toxicity of treatment. No significant financial relationships to disclose.
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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 | 0.000 | 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".