**6.1. Future work**

The typical results shown with the hybrid imaging system is applicable at present only to structural NDT for which it was designed. In order to produce true B-mode images for medical applications requires further work on the design of transducers and the sonoptical geometry to satisfy the conditions necessary for body tissue imaging, while accommodating the required dynamic range. In particular, it should be noted that the technique of image reconstruction is based on amplitude and phase integrity of signals; thus the inter-element uniformity of transducer elements and channels are crucial. In the case of medical imaging, the transducer element spacing is much smaller compared to NDT applications for any given frequency. For the above NDT system, the arrays were constructed using ordinary PZT transducer material. This is unlikely to be satisfactory in the case of medical transducers utilizing the above imaging techniques, since the requirements of transducer specifications are different and much tighter compared to conventional imaging to achieve good performance. Hence, transducers with piezo-composites or PVDF material may have to be developed for this application. Although the present system is designed to produce imaging in 2-D, extension of this technology to 3-D imaging in real-time is a distinct possibility which needs to be explored. This work and the development of dynamic compensation hardware will be taken forward in the next phase of development.
