Non-Invasive Differential Temperature Monitoring Using Sensor Array for Microwave Hyperthermia Applications: A Subspace-Based Approach
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this manuscript the authors report on temperature monitoring strategy based on microwave imaging. They elaborate the formulation of the strategy and the development of the necessary algorithm. Finally they produce a comparative tests on simulated data against state of the art approximations.
The manuscript is intersting and well-written. The topic is also intersting and I recommend a quick and smooth publication of this work.
I have only a couple of comments:
Detailed comments and suggestions
1. The author should at least synthetically describe the TwIST algorithm.
2. There are some problems with Figures 5 and 6. Figure 5 has only one panel and in the text, the images of Figure 6 are referred to as Figure 5.
Author Response
Please see the attached response to reviewer 1.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe monitoring of temperature using an array of sensor Non-Invasive Differential Temperature Monitoring Using a Sensor Array.
In this case a "Subspace-Based Approach" for micro-wave hyperthermia applications is proposed using a non-invasive sensor array.
According the authors, a more accurate total field estimation through primary induced currents is obtained and the validation has been performed using a 2D numerical breast phantom under various temperature conditions and noise levels.
Authors performed measurements and tests obtaining results that of course need improvements in the approach proposed. In particularly, authors affirm that their method "requires additional computational time for calculating primary induced currents".
The topic is relevant to the field and more improvements, according the authors, are desirable. Considering the results reported by authors, "The numerical results demonstrate that in noise-free conditions, both methods show satisfactory reconstruction capabilities, while our method maintains more consistent performance across different temperature levels compared to the BA method". For the BA method "performance deteriorates significantly for temperatures above 42°C under SNR = 20 dB". In my opinion conclusions are consistent and authors identify the aspects that have to be go into detail.
Tables and figures are appropriate for the argument proposed. No more comments to add.
Author Response
Please see the attached file for the responses to reviewer 2.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper presents a method for temperature monitoring in microwave hyperthermia applications in the case of absence of noise as well as in the case of noisy environment (SNR = 20 dB and 30 dB). The proposed method has been validated by simulations in the case of breast tumor detection. I recommend the following revisions:
1) I think that the original title “Non-Invasive Differential Temperature Monitoring Using Sensor Array: A Subspace-Based Approach” should be changed to “Non-Invasive Differential Temperature Monitoring Using Sensor Array for Microwave Hyperthermia Applications: A Subspace-Based Approach”.
2) The authors should discuss in more details how the proposed method improves the state-of-the-art and, in particular, the difference with the authors previous work on the same research line (Ref. [23]).
3) The parameters that express the contrast function at lines 128-129 must be defined. Moreover, the parameter H0 in equation 2 must be defined.
4) At lines 137-140, the sentence “In this study, the breast is embedded in Domain D, surrounded by 30 antennas arranged uniformly on a circle with a 10 cm radius. Each antenna is treated as a line source within the FDTD scheme. When one antenna is transmitting, the remaining antennas act as receivers, leading to a total of Nt = 10 transmitters and Nr = 30 receivers” is not clear. If the total number of antennas are 30, how is it possible to have 10 transmitters and 30 receivers? Please, explain it in more details.
5) At line 150, with reference to equation 6, it is written “where Ebac denotes the secondary incident field computed using equation (4) with contrast obtained from the contrast of the image domain at normal temperature”. However, Ebac is not defined in equation 4.
6) At lines 212-214 it is written “Based on the trends observed in Figure 2, the temperature-permittivity coefficient is -0.25% and the temperature-conductivity coefficient is +1%”. However, in Fig. 2 the permittivity vs temperature characteristic and the conductivity vs temperature characteristic are presented in three cases (liver, fat, blood). How such values are calculated?
7) In Table 1 the value of Th at 45°C is the same for BA and the proposed method. Is this correct?
Author Response
Please see the attached file for the responses to reviewer 3.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors revised the paper according to the Reviewer comments. It can be accepted for publication.
