Development of photoacoustic spectral response technique for biomedical applications

Abstract

Despite huge potential of PA technique, Conventional PA imaging alone would not bring out many advantages of this technique and would depend only on optical absorption as parameter. Obtaining different mechano-biological properties of the tissues would complement the screening and also aid in better understanding of the disease and the pathological conditions as well. In this context, instead of focussing on PA imaging, PA signals can be used to quantitatively extract the mechano-biological information of the biological tissues. Therefore, the primary objective of the thesis would be to develop photoacoustic experiment for obtaining the signal response and explore diagnosis based on mechano-biological properties of the tissues like tissue elasticity, density etc. Followed by these information, the setup would be applied to tissue phantoms to elicit mechano-biological information. In this process, different signal processing techniques in time as well as frequency domain would be applied to elicit elasticity dependent information from tissues. Subsequently, some of the issues faced in conventional PA imaging would be addressed. Differentiating blood clot in the presence of blood would be the first application where the continuous process of clot formation is explained through elasticity information obtained through the developed photoacoustic Spectral Response (PASR). Following this, different applications such as pneumonia detection, breast cancer detection using time-frequency analysis would be explored and critical functional information of the tissues is obtained. The detailed objectives are given as follows: * Development and characterisation of PA spectral response setup for different disease diagnosis and study * Theoretical analysis to understand relation between PA spectral parameters and sample’s elasticity * To validate the theoretical analysis with simulation and tissue mimicking phantom study. * Applying this technique for various applications such as blood and blood clot differentiation, early stage of Pneumonia (red hepatisation) detection, classifying human breast masses i.e. normal, benign and malignant and differentiating coagulated tissue from normal. * Utilising advance signal processing tools to extract time domain and frequency domain features of PA signal and correlating with tissues elasticity. Comparing the obtained results with standard technique like histopathology.