SU‐FF‐I‐166: Prostate Volume Contouring: Delineation Variations Using CT Versus Combined CT + US for Image‐Guided Radiotherapy
Bibliographic record
Abstract
Purpose: To verify if 3D‐US may be helpful in the definition of prostate for external beam radiotherapy Method and Materials: The clinical study involved ten patients with localized prostate cancer receiving conformal radiation between January and April 2009. Patients underwent a planning CT scan and a pelvic MR scan Prior to each scan (and subsequently before each fraction of radiotherapy) patients were asked to evacuate their bowels, and to have a comfortably full bladder. Immediately after the CT scan for planning is done, a trans‐abdominal 3D‐US image (Clarity, Resonant Medical, Toronto, CA) is acquired with the patient in the exact same position. With the help of a ceiling‐mounted tracking camera and 3D‐ultrasound (3D‐US) probe with active infrared sensors in the planning room, is possible to obtain an accurate spatial reconstruction of the ultrasound pixels in relation to the room's global coordinate system making feasible a simple superimposition between CT and US images . The MR scan was performed soon after the CT (1/2 hour) and the patient underwent CT and MRI in the planned treatment position with an indexed shaped knee rest and indexed ankle support A routine T2‐weighted prostate pulse sequence with a TE of 90 ms and a slice thickness of 4 mm was used. Results: No significative variations among observers considering together all the modalities imaging are registered (p=0.629). Significative variations between the three modalities considering together all the observers are reported (p=0.038). No significative variations of dosimetric predictors were found (p=0.965). Conclusion: 3D‐US have been shown to correlate well with MR in reducing volume respect to the TC. Dose to OAR is not significatively reduced even if MRI imaging is considered. However 3D‐US may be confirmed as a very good technique of imaging for prostate and thus for IGRT of prostate cancer.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".