Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Here are my comments:

1) Kindly change the abstract, and focus more on the novelty of the paper which seems to be missing.

2) Some important references are missing in the introduction:

i) Line: 27 - ultrasonic transducers, the authors are highly encouraged to cite important transducer review papers:

(a) DOI: 10.34133/2022/9764501

(b) https://doi.org/10.1038/s41378-023-00555-7

(c) https://doi.org/10.1016/j.zemedi.2023.04.010

ii) Line 30 – brain imaging: https://doi.org/10.1117/12.2546854

3) Page 2, line 61 to 65 must be elaborated.

4) page 2, line 58: The authors state that TIR previously has been obtained through experiments. However, the authors use the OPAS, which is an experimental entity to present their method. Authors to justify.

5) Are the content of the sections 2 and 3 authors contributions? Please clearly state in the manuscript

 

6) Figures need a lot of improvement. Words in the figures are barely visible.  

Author Response

Dear reviewer，please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors, please revise the attached files.

 

Comments for author File: Comments.pdf

Author Response

Dear reviewer，please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents a method to extract the transducer impulse from the observed photoacoustic signal and its simulation results. The work is well presented in details. I only have minor comments:

1. Please comment or give more analysis on the accuracy of the proposed method. How is the accuracy compared with the other methods?

2. Did the authors conduct any optimization on the number of transducers and OPAS length in this method? Is there any guidance on choosing the optimized numbers of them?  

Comments on the Quality of English Language

Minor editing.

Author Response

Dear reviewer，please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

In the manuscript “A method for solving the transducers impulse response (TIR) in photoacoustic imaging” the authors describe a computational algorithm to infer the TIR of a photoacoustic imaging system based on the direct calculation of the observed photoacoustic signal data (OPAS) and comparison with the photoacoustic pressure signal (PAPS) at given positions.

Regarding the scope and scientific impact of the manuscript, it frames well within the scope of the MDPI Applied Sciences and may have an interesting impact on the community dedicated to photoacoustic imaging. Yet, the present form of the manuscript presents issues that must be addressed to fulfill the standards of the publication.

Major issues:

1.Introduction: the introduction is poorly written in terms of phrase linking and fluency and thus must be improved. Besides, I believe that it would benefit from the inclusion of references regarding TIR and spatial translations such as  10.1038/s41467-020-16565-2 and 10.1103/PhysRevApplied.14.034026 which report complete methods for complete spatial and temporal characterization of the transducer.

2.It is not clear how eq.(2) is obtained from eq.(1): the authors should include proper description on that(i.e. introduce Green’s function in 3D), in particular, because it disregards the spatial coordinates on the PAPS x(t) in eq.(2) which contained on x(r,t) in eq.(1). The authors should also clarify this distinction and if both functions correspond to the same PAPS. Disregarding the spatial coordinates implies approximations that must be clear to the reader in order to understand the validity of the approach. Thus it must also be commented properly.

3.The method generalizes for various transducers and Equation (4) assumes that the response H is the same for every transducer. How is this assumption supported by experimental evidence from previous results? This is the basis of the method and should be properly discussed in the manuscript.

4.Finding the PAPS vector utilizing SVD method is interesting from a computational standpoint, but may struggle in the presence of noise. The authors should discuss (preferably with data) the influence of noise, in particular in the determination of the PAPS size.

5.Utilizing the LS algorithm and the pseudo-inverse solution in eq.(25) can often result in overfitting issues, which may affect drastically the results in the presence of experimentally noisy data. The authors should comment on this and verify if the results still hold for noisy signals. Besides, they could use regularized alternatives of (25) which in my opinion would be more suitable for such data-driven inversion.

In my opinion, and given the lack of solid results/discussion regarding possible effects of the noise nor evidence of the applicability of the method in experimental conditions, the present manuscript should be reviewed properly to be accepted for publication.

Additional minor issues:

1.Consider utilizing another letter rather than H either for heat source (eq.1) or for TIR transform (eq.4) to avoid confusion;
2.Please verify if matrix (18) is correctly defined, in particular the second to last line;
3.Please verify the phrase starting in line 283.

Comments on the Quality of English Language

The quality can be improved in terms of linking of ideas and text, in particular in the section describing the algorithm.

Author Response

Dear reviewer，please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript seems to be sufficiently improved. No further changes are required.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have made all the corrections I suggested. The article can be published as written.

Reviewer 4 Report

Comments and Suggestions for Authors

Following major improvements made by the authors, I can recommend the acceptance of the revised form of the manuscript.

Comments on the Quality of English Language

The quality of written English is acceptable.