Evaluation of the stability of (99m)Tc-ECD and stabilized (99m)Tc-HMPAO stored in syringes.
Bibliographic record
Abstract
OBJECTIVE: To determine and compare the stability of (99m)Tc-ECD and stabilized (99m)Tc-HMPAO when stored in syringes over an 8-h period. METHODS: (99m)Tc-ECD and stabilized (99m)Tc-HMPAO were prepared according to the manufacturers' protocols, with the following exception: eluate less than 60 min old was used to prepare (99m)Tc-HMPAO rather than the recommended 30 min. Once prepared, 185 MBq (5 mCi) of both products were drawn into 5-mL syringes and allowed to sit at room temperature. At 2, 4, 6, and 8 h after preparation, the radiochemical purity (RCP) of the contents of the syringes was determined and compared to the RCP of the products in vials. Retention of activity of each product in syringes was also evaluated by measuring activity remaining in each syringe (and filter, in the case of (99m)Tc-HMPAO) after expressing its contents. RESULTS: The RCP of stabilized (99m)Tc-HMPAO stored in syringes decreased from a mean of 87.7% at 2 h to 74.0% at 8 h after preparation. In contrast, (99m)Tc-ECD retained an RCP of greater than 94% throughout the time tested. The impurity that appeared to increase over time with (99m)Tc-HMPAO was found to be sodium pertechnetate. Total retention of activity remaining in the syringe and filter ranged from 11.6% at 2 h to 9.5% at 8 h for (99m)Tc-HMPAO; the syringe itself retained less than 5% of the total activity at all time periods. (99m)Tc-ECD exhibited 6.2% to 11.3% retention of activity in the syringe. The sorption of sodium pertechnetate to the syringe for the same time period was less than 1%. CONCLUSIONS: (99m)Tc-ECD is a more stable product than stabilized (99m)Tc-HMPAO in a syringe. Both products demonstrate retention of radioactivity in the syringe. Some of this retention may denote sorption of the products to plastic.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".