Study on methods to extract high contrast image in active dynamic thermography

ABSTRACT

In the present study, image reconstruction methods are applied in active dynamic thermography (ADT) to visualize the superficial blood vessel with high contrast. ADT is performed on the left forearm of a human subject by applying cooling based external thermal stimulation. Both non-parametrized, viz. sequence image, sequentially subtracted image, Discrete Fourier Transformation (phase and amplitude image), and Thermographic Signal Reconstruction (TSR), and parametrized, viz. Tau time (τ), $d{T}_{norm},t_{90-10n},$ and Tissue Activity Ratio $(TAR)$, types of image reconstruction methods are used. To perform a quantitative comparison, among the image reconstruction methods, the image contrast value is evaluated. While sequentially subtracted image provides a high contrast image in non-parametrized image reconstruction methods, for parametrized image reconstruction methods, it is $TAR$. Among all the methods considered, $TAR$ provides the best contrast image followed by τ image method.

KEYWORDS:

• Active dynamic thermography
• thermal image reconstruction
• image contrast
• Tissue Activity Ratio
• Tau time

Acknowledgments

The authors would like to acknowledge their heartfelt gratitude to Eetarp Engineering Pte. Ltd., Singapore for providing the IR thermal camera support, and Mr. Gaurav Singh, Ph.D. Scholar, School of Computer Science and Engineering, NTU Singapore, for his consultation on image processing.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work has been supported by SingHealth-NTU collaborative research grant [Grant number: SHS-NTU/014/2016].

Notes on contributors

Ashish Saxena

Ashish Saxena is a full time Ph.D. student at Nanyang Technological University, Singapore. He is currently working on development of passive and active thermographic methods (tools/device) to perform patient screening for cardiovascular related diseases. With a mechanical and thermal engineering background, his research interests include studying hemodynamics influenced tissue heat transfer using computational fluid dynamics methods, thermography-based sensing and imaging, biomedical diagnostic/clinical research, and thermo-regulation of solar photovoltaics.

Vignesh Raman

Vignesh Raman has conferred Master of Science in aerospace engineering with specialization in thermal imaging. He has worked in thermography-based material characterization, defect identification, and medical thermal imaging of human blood vessels, with the focus on data collection and pre- and post-processing of thermal images. His research interests include image processing, motion artifact, machine learning, deep learning, and data analysis.

E. Y. K. Ng

E. Y. K. Ng, currently serving as an Associate Professor at Nanyang Technological University, Singapore, has obtained his Ph.D from Cambridge University. He is the Editor-in-Chief for the ISI Journal of Mechanics in Medicine and Biology and the Founding Editor-in-Chief for the ISI indexed Journal of Medical Imaging and Health Informatics. His main area of research is human physiology, biomedical engineering, computational fluid dynamics and numerical heat transfer.