The preparation of strontium-substituted hydroxyapatite bone phantoms with high strontium concentrations
Bibliographic record
Abstract
The current in vivo x-ray fluorescence spectrometry (IVXRF)-based method of bone strontium quantification is dependent on calibration against plaster of Paris (poP; ) calibrators/phantoms. Issues with the dissimilarity of the poP in comparison to bone mineral and the known issue with high levels of strontium contamination in commercial poP materials has led to the development of a strontium-free hydroxyapatite bone mineral phantom material. The analyte is introduced into this material by doping of a high concentration setting solution. This phantom material is not particularly well suited for the preparation of strontium containing bone phantoms which are high in strontium concentration (in the mol % concentration range) and thus when the (Ca + Sr)/P mole ratio is to be kept at 1.67: that of hydroxyapatite. This work thus evaluates the feasibility of preparing high concentration strontium-substituted hydroxyapatite phantoms using a CaHPO4 2H2O/Ca(OH)2/Sr(OH)2 8H2O cement mixture. It was found that a strontium-substituted HAp phantom material can be prepared by mixing suitable quantities of CaHPO4 2H2O, Ca(OH)2 and Sr(OH)2 8H2O to a (Ca + Sr)/P mole ratio of 1.67. Setting of the phantom using a 1 M setting solution (to increase phosphate concentration) produced a phantom composed of ()5(PO4)3OH of known strontium concentration. The final phantom material was found to be a strontium-substituted product (through x-ray diffraction and Raman spectroscopy measurements) to the degree of substitution expected. This work thus describes the preparation of a bone phantom material which can be used for the calibration of IVXRF systems of bone strontium quantification, as well as for other modalities (i.e. dual energy x-ray absorptiometry and quantitative ultrasound) in the case that bone strontium concentrations are expected to be high such as in the case of individuals taking strontium salts for the treatment/prevention of osteoporosis.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".