Master's Thesis : Influence of pressure on Terahertz imaging of fresh animal tissues

Abstract

Breast cancer is the most common form of cancer affecting women in Europe. Tumours related to this cancer can be extracted through lumpectomy. During this surgery, the tumour and a margin of healthy tissues are extracted. The characterisation of this margin is done by histology but the results that give information on the probability for recurrence takes several hours to a day. To decrease the time needed for margin characterisation, medical imaging can be used. In this field, terahertz (THz) imaging appears promising due to its low price, low volume and because it is non-ionising.

This master thesis is about the application of THz imaging in margin characterisation during lumpectomies. More specifically, it deals with the influence of pressure on fresh biological tissues. To quantify the effects of pressure, experiments on pork lean meat and fat have been carried out with the TeraPulse 4000 machine developed by TeraView. During these experiments, pressure was monitored with a measurement system using force sensing resistors (FSRs) placed between two polytetrafluoroethylene (PTFE) plates. The measured voltages related to the FSRs values variations were recorded with an ArduinoTM and an application developed in C#. The data acquired by the TeraPulse 4000 were then analysed with MatLab. Moreover, the optical properties of the sample were computed when it was imaged in transmission mode. Three experiments have been carried out in this study: THz imaging of a piece of brass in reflection and transmission modes, THz imaging of meat and fat in transmission mode, and THz imaging of meat and fat in reflection mode. The results of these experiments showed that several other parameters in addition to pressure influenced the samples THz imaging. As a consequence, the influence of pressure alone was not distinguishable. However, the experiments showed that monitoring of pressure is important in biomedical applications to improve the sample adherence to its holder when imaging in reflection mode which is more used in this field than transmission one.