TU‐C‐204B‐07: A Comparative Study for Daily Localization with 3D Ultrasound, Cone Beam CT, Implanted Prostate Fiducial Markers and Calypso 4D Localization System for Patients Undergoing IGRT for Prostate Cancer
Bibliographic record
Abstract
Purpose: To assess the accuracy and dosimetric implications of multi‐modality, online image‐guided localization methods, including intra‐modality 3D prostate ultrasound, cone beam CT (CBCT), implanted prostate markers and Calypso 4D localization for patients undergoing external beam radiation treatment with IMRT for prostate carcinoma. Materials and methods: Fifteen prostate cancer patients were imaged using IGRT techniques using the following daily imaging sequence: CBCT, kV orthogonal x‐rays of implanted fiducial markers using the On Board Imager (OBI) on a Varian Trilogy TX linac (Varian Medical Systems, Palo Alto CA), perform patient shifts based on ClarityTM intramodality 3D U/S‐IGRT system (Resonant Medical Inc., Montreal, Canada) per an IRB‐approved protocol, kV x‐rays (post patient‐shift), and Calypso 4D Localization System (Calypso Medical, Seattle, Washington) for intrafraction motion monitoring, finally treat patient. Residual motion was assessed from differences between kV images of marker positions performed prior to and after U/S‐based shifts. Dosimetric differences were evaluated by computing treatment plans using the average shift values generated by the image‐guided localization methods. Results: The anterior — posterior direction had the largest recorded average shifts, overall being less than 7 mm. Most (65%) of the average shifts calculated between the various IGRT modalities were within 3 mm of each other, and the rest within 3 – 7 mm. Changes in inter‐fiducial distances between simulation and treatment were found to be on average 1.5 mm (maximum of 5.8 mm). Possible causes are rotations, migration and/or prostate size/shape changes. DVHs for the rectum, and bladder show in some instances significant increases in dose received when measured setup shifts were included. Conclusion: The comparison of multi‐modality IGRT techniques is subject to many uncertainties, including prostate intrafraction motion (89% within 3 mm range), changes in the prostate position due to bladder/rectal filling during the time between image acquisitions, and migration of fiducial markers.
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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 | 0.002 |
| 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 | 0.001 | 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".