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Direct current electrical resistance measurement techniques for assessment of colorectal cancer during laparoscopic surgery

Chandler, James Henry (2015) Direct current electrical resistance measurement techniques for assessment of colorectal cancer during laparoscopic surgery. PhD thesis, University of Leeds.

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Abstract

The next generation of surgical tools will employ intraoperative sensing technologies to provide real-time information to the surgeon. Sensing in this way may facilitate personalised tissue resections during cancer surgery, thereby reducing radicality and improving outcomes for the patient. This thesis details the development and testing of electrochemical based sensing techniques aimed at integration into the next generation of laparoscopic surgical tools. Literature reviewed as part of the work highlights the broad nature of surgically appropriate sensing technologies. Based on the features of simplicity and scalability, the biogalvanic tissue characterisation technique was explored as the most practically suitable candidate. Development and systematic testing of a biogalvanic measurement system with porcine tissues showed variation that is not explained using the current system model. Correlation with electrochemical measurements verified this unaccounted system complexity. Electrode polarisation and diffusion controlled reduction at the cathode limit the tissue specificity of the output metrics. An improved analytic model fitting technique was developed to reduce the influence of the electrodes. Through collaborative development of a numerical model of the system, the practical limitations of the biogalvanic techniques as a surgical sensor were realised. To mitigate these limitations, a novel galvanostatic technique for improved resistance characterisation was developed. Testing was conducted on ex vivo tissues, showing stability for relevant parametric variation. Surgical applicability was found from a practical perspective, with results showing low sensitivity to switching rate, current range and tissue contact conditions. Testing was also conducted on a number of freshly excised cancerous human colon samples. Measurements were centralised on each tumour and compared to a corresponding healthy region. Every case showed a highly significant difference between tissue types with cancerous tissues having a consistently lower resistance. These findings suggest that the proposed technique of multi-reference galvanostatic resistance characterisation may be a suitable candidate for integration into surgical tools for colorectal cancer surgery.

Item Type: Thesis (PhD)
Related URLs:
Keywords: Colorectal Cancer Sensing Galvanic Bioimpedance Surgery Laparoscopic Resistance
Academic Units: The University of Leeds > Faculty of Engineering (Leeds) > School of Mechanical Engineering (Leeds)
The University of Leeds > Faculty of Engineering (Leeds) > School of Mechanical Engineering (Leeds) > Institute of Engineering Systems and Design (iESD)(Leeds)
The University of Leeds > Faculty of Engineering (Leeds) > School of Mechanical Engineering (Leeds) > Institute of Engineering Thermofluids, Surfaces & Interfaces (iETSI) (Leeds)
Identification Number/EthosID: uk.bl.ethos.682268
Depositing User: James Henry Chandler
Date Deposited: 06 Apr 2016 10:39
Last Modified: 26 Apr 2016 15:45
URI: http://etheses.whiterose.ac.uk/id/eprint/12434

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