P2484Radiation dose reduction in cardiac CT: results from the prospective multicenter registry on radiation dose estimates of cardiac CT angiography in daily practice in 2017
Bibliographic record
Abstract
Background: The radiation exposure reported in cardiac CT studies has raised concerns. In 2007, the international PROTECTION I registry estimated the radiation exposure of cardiac CT angiographies with a median dose-length product (DLP) of 885 mGy*cm. Since then, numerous advances in CT technology as well as scan protocols have been developed for dose reduction, but their efficacy in clinical practice is largely unknown. Purpose: The PROTECTION VI study is a multicenter, prospective, worldwide registry designed to evaluate radiation dose exposure and utilization of dosesaving strategies for contrast-enhanced cardiac CT angiography in daily practice. Methods: 60 study sites from 32 different countries participated and enrolled all patients undergoing cardiac CT during one calendar month in 2017. To date core-lab collected image and scan data of 4500 patients have been analyzed. DLP was the main outcome measure. Linear regression analysis was performed to identify independent predictors associated with dose. Results: The median DLP of 4500 cardiac CT studies was 244 mGy*cm (interquartile range: 148 to 360 mGy*cm), which corresponds to an estimated effective dose of 3.4 mSv (conversion factor k = 0.014 mSv*(mGy*cm)-1). When compared with PROTECTION I, the DLP was reduced by approximately 72% (p<0.001). A >30x variability in median DLP was observed between study sites (range of median DLP: 74 to 2289 mGy*cm). The most frequent indication for cardiac CT was the evaluation of coronary artery disease in 88% of patients. Among patient-related factors, multivariable linear regression analysis identified body weight as the predominant independent predictor for higher radiation dose of coronary CT angiography, whereas the use of low tube voltage and the selection of scan protocols were predominant acquisition-related independent predictors for radiation exposure.
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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 | 0.006 | 0.017 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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".