Investigation of the impact on image resolution of trace impurities found in cyclotron-produced 99mTc pertechnetate
Bibliographic record
Abstract
1749 Objectives Cyclotron-produced 99mTc pertechnetate (CPP) is an alternative to generator-produced 99mTc pertechnetate (GPP) but will contain very small quantities of other radioactive Tc isotopes1,2 that emit high-energy (>500 keV) γ-photons. These photons may penetrate collimator septa and deposit energy in the scintillator. The objective of this study was to quantify the effect of Tc impurities on the image spatial resolution. Methods We quantified spatial resolution in terms of the full width half maximum (FWHM) of the point spread function (PSF) and the modulation transfer function (MTF) of the imaging system. The PSF and MTF of CPP were estimated from Monte Carlo (GATE) simulations of point sources located 20 cm from the center of the detector. Five sources, which contained increasing proportion of radioactive Tc impurities, were simulated. The quantities of other Tc isotopes were established to correspond to increased patient radiation doses of 0%, 10%, 30% and 100% over pure 99mTc. The LEHR collimator and 140±10% keV window were used for simulation. Results The FWHM increased by Conclusions Impurities present in CPP may increase the FWHM of the PSF and result in a drop of MTF at low-frequencies. However, for product meeting radionuclide purity specifications that are proposed to be used in clinical practice ( Research Support This work was supported by Natural Resources Canada through the Non-reactor-based Isotope Supply Contribution Program and TRIUMF core funding.
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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 | 0.003 |
| 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".