TH-CD-304-06: Amplitude and Frequency Characteristics of Acoustic Waves Induced Following Radiotherapy Linear Accelerator Irradiation
Bibliographic record
Abstract
Purpose: To enhance understanding of the characteristics of acoustic waves induced following irradiation by a linac photon beam through experiments and simulations. Such waves have potential applications in in vivo dosimetry since their properties are related to the dose distribution following a single pulse of irradiation. Methods: The acoustic waves induced following linac photon beam irradiation of different metal blocks suspended in a water tank were investigated. Experimentally, these waves were detected with an ultrasound transducer and amplification electronics. Computationally, the acoustic waves were modeled by combining Monte Carlo dose calculations and acoustic wave transport techniques. The effect of varying metal block size, material, depth, and linac photon beam energy on the amplitude and frequency of the induced acoustic signal was investigated. Results: Experimental and simulated acoustic waveforms indicated that increasing photon beam energy and decreasing metal block depth along the central axis increases signal amplitude by an amount proportional to the increased dose deposited in the block. Decreasing in-plane lead block width increased the frequency of acoustic waves due to the smaller dimension of the lead-induced perturbation in the global dose distribution. Varying the metal block material from lead to aluminum resulted in smaller amplitude acoustic waves due to aluminum's lower electron density, while aluminum's higher speed of sound resulted in higher frequency waves. Both simulated and experimental waveforms showed similar trends in signal amplitude and frequency when set-up variables were altered. Conclusion: This study revealed factors that affect the amplitude and frequency of radiation-induced acoustic waves and their relation to the deposited dose characteristics. The agreement between simulated and experimental waveforms verifies the simulation workflow's ability to model such acoustic waves, and indicates that it could be utilized to explore more complex irradiation scenarios and potentially aid in the development of experimental detection systems for in vivo dosimetry. This work was supported by NSERC and CIHR grants. S.H. acknowledges support by the NSERC CREATE Medical Physics Research Training Network grant 432290.
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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) | 0.002 | 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".