Frequency-domain photothermoacoustic imaging contrast enhancement with a CW laser and non-linear frequency modulation chirps
Bibliographic record
Abstract
The application of photoacoustic (PA) phenomena to medical imaging has been investigated for more than a decade. To implement this modality, one may choose between two types of laser sources, pulsed or continuous wave (CW). This selection will affect all features of the imaging technique. Nowadays pulsed lasers are the state-of-the-art technique in the PTA research. In this work we report frequency-domain photothermoacoustic imaging using linear and non-linear frequency chirps with a CW laser. The images produced using turbid tissue phantoms with subsurface inclusions were compared according to their contrast and depth resolution of absorbing lesions. In the CW method, in addition to the image produced by the amplitude of the cross-correlation between input and output signals, another image which is generated by the phase of the correlation signal is also available. The application of nonlinear frequency modulation instead of the standard linear frequency chirps introduced in our laboratory is demonstrated. These features are additional degrees of freedom uniquely available to the CW (but not to the pulsed laser) method.
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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 | 0.001 |
| 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".