Design of colon phantoms and a colon phantom motorized measuring system to verify the operation of a microwave-based diagnostic device

Abstract

Microwave imaging (MWI) is an emerging medical imaging technique with promising biomedical applications. In line with this research area, MiWEndo Solutions is a spinoff devoted to the development of a MWI device for colorectal cancer diagnosis called MiWEndo, which is attached to the regular colonoscope. Before its actual commercialization, a fundamental step towards the validation of the MiWEndo prototype is the design of realistic colon tissue-mimicking phantoms. Such phantoms allow the assessment of the imaging system performance under well controlled and reproducible conditions. In this thesis, a new, simple, and highly reproducible phantom recipe based on polyvinylpyrrolidone (PVP) has been developed to mimic healthy colon mucosa. Moreover, a comparative study between the currently used oil-based phantom recipe and the new PVP phantom has been conducted to assess the lifespan and stability of each type of fabricated phantom. It has been concluded that PVP phantoms must be conserved in the fridge for increased stability. With this conservation protocol, the PVP recipe shows a similar lifespan as the oil-based one. Nevertheless, due to both the limited number of samples and time, further studies must be carried out to conclusively determine the recipe with larger stability. Furthermore, a colon phantom motorized measuring system has been designed to improve repeatability and reliability in the measurements of the phantoms. The system consists of an XYZ motorized positioning system, an Arduino Nano, stepper motor drivers and Arduino IDE firmware. Even though further improvements will be required once implemented, a first conception of a system that fulfils the established requirements has been obtained, based on reasonable-cost and simple-implementation components. Besides, a successful proof of concept of the measuring system has been carried out, concluding that a further implementation of the system seems viable.