Retrospective dosimetric evaluation of VMAT plans for prostate cancer treatment
Bibliographic record
Abstract
Abstract Background Radiation therapy (RT) remains a common and effective treatment modality for patients with locally advanced prostate cancer. Technological advancements over the past decade have resulted in the introduction of intensity-modulated radiation therapy (IMRT) planning and delivery techniques that maximise the dose of radiation delivered to the prostate while sparing organs at risk (OAR). A more recent and evolving IMRT technique, called volumetric-modulated arc therapy (VMAT), involves a continuous irradiation at a constant or variable dose rate when the gantry rotates around the prostate using one or more arcs. Materials and methods This paper reports on a dosimetric evaluation of our implementation of VMAT technique for prostate cancer treatment. A retrospective analysis of VMAT plans was performed for 300 prostate cancer patients treated during the period of January 2013 to December 2014. Two prescription cohorts of patients treated to a dose of 78 Gy in 39 fractions as the primary radiation therapy treatment (XRT) and 66 Gy in 33 fractions as a post-op or salvage XRT were considered. Results The mean and maximal doses, dose inhomogeneities and conformity indexes for the planning target volumes were evaluated for each prescription cohort of patients. Similarly, the doses to OAR such as rectum, bladder and femoral heads were also assessed for various dose levels. Conclusion This study shows that highly conformal radiation dose distribution for the treatment of prostate cancer is achievable with the VMAT technique. It provides evidence to support the adoption of such conformal technology in many disease sites such as the prostate. We believe that our experience reported here could help form the foundation for individual institutions to evaluate and develop the most suitable planning criteria tailored to their own needs and priority. This endeavour hopefully will provide further improvement in the planning process and, therefore, help achieve an effective and efficient delivery of radiotherapy for 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 | 0.003 | 0.009 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".