Automated and Controlled System for Analysis of Residual Limbs Thermograms of Transtibial Amputees

Round 1

Reviewer 1 Report

Dear Authors

At the outset, I would like to congratulate you very warmly on the research carried out and the results obtained. The proposed topic has a very wide application significance and high diagnostic application. Despite the very good substantive preparation of the article, I would like to submit the following comments that may improve the readability and general reception of the publication.

• I propose to provide an unambiguous description of the calibration procedure of the equipment.
• Do you adopt a fixed setting of the emissivity of the object in the research?
• How RTC (reflected temperature compensation) is set
• How were measurement errors eliminated resulting from non-axial measurement (shape and dimensions of the stump) of the distance of the cameras from the object and how important are changes in ambient temperature (air movements or floor emissivity), the degree of healing of the stump (time from amputation to the test performed). In the case of thermal imaging measurements with such a high accuracy of 0.1°C, metabolic processes occurring after amputations may change with the extension of the time after surgery.
• Do you use positioning that takes into account the anthropometric and goniometric characteristics of the patient?
• To what extent individual measurements are repetitive, whether you have verified the measurements by performing several tests for the same patient, taking into account different stump positioning. If so, at what level was the measurement error.
• There are empty graphic symbols in the text m.in. line 338
• No photo 17
• Are all pattern derivations and transformations necessary? Maybe it is better to focus on a broader description of individual algorithms and the etiology of their operation?
• Pictures with more data are illegible (figs. 9, 12, 18, etc.) – please use a different technique of presenting the results.
• The fonts in the tables are not consistent – please use the same font in all tables.
• The conclusions are laconic, they should clearly refer to the research part and summarize the presented research.

Author Response

Reviewer 1
Dear Authors
At the outset, I would like to congratulate you very warmly on the research carried out and the results obtained. The proposed topic has a very wide application significance and high diagnostic application.
Despite the very good substantive preparation of the article, I would like to submit the following comments that may improve the readability and general reception of the publication.
Answer: We appreciate your opinion about our manuscript. We thank your comments and suggestions that have contributed to improving our revised version.
Comment 1: I propose to provide an unambiguous description of the calibration procedure of the equipment. Do you adopt a fixed setting of the emissivity of the object in the research? How RTC (reflected temperature compensation) is set? How were measurement errors eliminated resulting from non-axial measurement (shape and dimensions of the stump) of the distance of the cameras from the object and how important change in ambient temperature (air movements or floor emissivity), the degree of healing of the stump (time from amputation to the test performed). In the case of thermal imaging measurements with such high accuracy of 0.1°C, metabolic processes occurring after amputations may change with the extension of the time after surgery.
Answer: Thanks for pointing out this. We have added more details about using the thermographic camera and the settings to explain the calibration procedure better. The new text is the following:
The thermographic camera used during this study was a FLIR C3 Thermal camera with WIFI. This camera requires a minimum focus distance of 0.15 meters, has a thermal sensitivity of less than 0.10°C, and measurement accuracy of +/- 2°C or +/- 2% at 25°C. It also has a set of parameters that can be tuned for specific tasks, for instance, in this study we set the emissivity value to 0.98, which is the
accepted emissivity value for human skin found in the literature. Also, a target distance was set to 0.45 meters, which is the distance between the camera and the center of the cabin. Proper camera calibration needs to be done by an authorized center, however, before the capture of the thermal images, the FLIR
C3 temperature range was set from 20 to 40°C, aiming to detect the temperature of the stump within this range in a way that color map variations can use for qualitative analysis. This temperature range was fixed by setting an environment temperature of 20°C and placing a glass of water at 40°C, 45
cm away from the camera. During the image processing stage, no reflected temperature compensation nor measurement errors were eliminated resulting from non-axial measurement of the distance of the camera from the object, however, these will be considered for further improvements in order to achieve a
more precise analysis. Changes in ambient temperature, e.g. background objects, were not considered at first. Once they were found to impair processing, the proposal of an automated cabin was suggested to isolate the stump from air movements and background objects with different emissivity values, in order to
improve processing performance. The selection of participants needs to satisfy the clinical trial protocol approved by an ethics committee (PR2021-01). All participants in this study must have at least one year since their amputation surgery.
Comment 2: Do you use positioning that takes into account the anthropometric and goniometric characteristics of the patient?
Answer: We thank the reviewer for this remark. The reviewer is right. We use positioning that considers the anthropometric and goniometric characteristics of the participant. The system is designed to modify the inclination angle according to the subject’s residual limb size. In addition, the radial distance can be adjusted to keep the distance set in the protocol for the measurement (45 cm).
Comment 3: To what extent individual measurements are repetitive, whether you have verified the measurements by performing several tests for the same patient, taking into account different stump positioning. If so, at what level was the measurement error.
Answer: Thanks for this remark. We did not perform a repeatability test or a reproducibility test for the system. However, we consider this for further tests and applications of the automated cabin.
Comment 4: There are empty graphic symbols in the text m.in. line 338
Answer: Thanks. The symbol in line 338 (□) denotes the final of the proof. We are not sure if this is the missing symbol the referee is pointing out.
Comment 5: No photo 17
Answer: Thank you. We have added this missing figure.
Comment 6: Are all pattern derivations and transformations necessary? Maybe it is better to focus on a broader description of individual algorithms and the etiology of their operation?
Answer: Thanks for pointing this out. However, we consider that all derivations and transformations were necessary for the description of the proposed model. About Algorithm 1, we have added a reference with more information about trajectory design based on sigmoidal functions [1].
Comment 7: Pictures with more data are illegible (figs. 9, 12, 18, etc.) – please use a different technique of presenting the results.
Answer: Thank you for this suggestion. We have changed the figures, we have enlarged some of them, and increased the font size for the graphs.
Comment 8: The fonts in the tables are not consistent, please use the same font in all tables.
Answer: Thank you. We homogenized all the fonts for the tables of the revised version of the paper.
Comment 9: The conclusions are laconic, they should clearly refer to the research part and summarize the presented research.
Answer: Thanks. We rewrote the Conclusions Section to improve the description, improve the readability, and clarify the final remarks for the outcomes of this work. The new Conclusions are as follows.
This paper presents the design of an automatic system to capture thermal pictures of the residual limbs of amputees. The motivation of such a device is to aid in the thermal image acquisition process within a confined space. The thermograms generated provide helpful information for analyzing the residual human limb in subjects with transtibial amputation. Such a study proposes a non-intrusive method to study the thermal activity on the amputee’s residual limb and seek a correlation to the quality of the socket.
The proposed cabin ensures the repeatability of the thermograms acquisition process and provides an isolated workspace, thus, improving the quality of the samples. The methodology consists of the design of the mechanical elements and parts of the system on computer-aided design software, the electronic
instrumentation, a graphic user interface (GUI), and the control algorithm based on a Barrier Lyapunov function to solve the trajectory tracking for the camera movements, numerical simulations to illustrate the functionality and the manufacture of a prototype. The GUI was designed to operate the device and
store and analyze the obtained data. The results obtained by implementing the control design on the automated cabin reveal that the thermal image acquisition process is completed following the desired trajectory with a mean squared tracking error of 0.0052. With this result, it is evident that the algorithm
successfully solved the tracking trajectory problem allowing the mobile platform to follow a smooth path with a maximum error setting, and it did not need the exact value of the system parameters. In addition, an example of the thermal images of two subjects and the results of processing this class of pictures using
the designed interface is shown. In further research, the system will be used in a clinical protocol to compare different sockets.
References:
[1] Ballesteros-Escamilla, M., Cruz-Ortiz, D., Salgado, I., Chairez, I. (2019). Hybrid position/force output feedback second-order sliding mode control for a prototype of an active orthosis used in back assisted mobilization. Medical Biological Engineering Computing, 57(9), 1843-1860.

Author Response File: Author Response.pdf

Reviewer 2 Report

The drawings included in the work require improvement.

Improve the readability of descriptions, enlarge elements in the drawings and increase the font size:

1. Figure 3. Flowchart showing the main steps for the development of a ….
2. Figure 4. Diagram for the functionality of the electronic part of….
3. Figure 5. Flowchart illustrates the user experience ……
4. Figure 8. The graph depicts the desired path ……
5. Figure 9. Figure shows the implementation of the control system using Simulink.
6. Figure 10. CAD of the designed cabin.
7. Figure 11. Assembly of the mobile platform for the thermal camera.
8. Figure 12. Main electronic components.
9. Figure 15. Evolution …..
10. Fiigure 18. Layout of the user interface, the user can choose to do the process manually or automati...

 Improve the readability of the waveforms:

1. Figure 13. Comparison of the position implementing a PD controller and…
2. Figure 14. Tracking error, comparison between the absolute error with PD controller and proposed
   controller……
3. Figure 16. Estimation of an unknown parameter.

 No drawing - empty space:

1. Figure 17. Performance of the control signal to fulfill the restriction.

 Some of the equations in the paper are not numbered and there is no reference in the content to the selected equations. The mathematical dependencies and equations contained in the paper are written in a different font - Check and correct.

Author Response

The response to the reviewer is in the attached document.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript submitted by Mariana Ballesteros et. al. deals with the complete design of an automatic system to capture and analyze the thermograms of the residual limbs for amputees. The authors interestingly presented the CAD modeling with the description of the materials and assembly, the electrical instrumentation, the control algorithm based on a Barrier Lyapunov Function, and a graphical user interface to operate the device and store and analyze the obtained data. 

Overall the manuscript is well written and interesting to read, however, i see the following issues that should be resolved before publishing this paper.

The font size of all figures should be increased throughout the paper. The font should be readable and understandable within the default view.

Author Response

The response to the reviewer is in the attached document.

Author Response File: Author Response.pdf

Reviewer 4 Report

This article presented an automated and controlled system for analysis of residual limbs thermograms of transtibial amputees. The work is solid with both theoretical and experimental justifications. The results are of very important practical value and should be published for the society. I would like to recommend it for publication after minor modifications.

 

I only have a few minor points for the authors to finalize their work:

1. The innovation of current work might be further clarified and enhanced to clarify the fundamanetal contribution of current work.

 

2. It looks some former closely related modeling or measuring regarding mobile infrared thermal imaging on human body including knee, neck etc. are missiong. Such as: a) Study on an automated analysis method of knee osteoarthritis screening using medical infrared thermography, Journal of Medical and Biological Engineering, 33: 471-477, 2013. For a complete background, a further literature search and discussin might be helpful.

 

3. For better presentation, some writings and drawings can be improved. Such as Figure 9, Figures 13-17 etc. quality can be clearer.

 

4. Will the same method work well for other similar health care case?

Author Response

The response to the reviewer is in the attached document.

Author Response File: Author Response.pdf