title: Characterisation of a fibre optic Raman probe within a hypodermic needle.
abstract: We demonstrate the first use of a multifibre Raman probe that fits inside the bore of a hypodermic needle. A Raman probe containing multiple collection fibres provides improved signal collection efficiency in biological samples compared with a previous two-fibre design. Furthermore, probe performance (signal-to-noise ratios) compared favourably with the performance achieved in previous Raman microscope experiments able to distinguish between benign lymph nodes, primary malignancies in lymph nodes and secondary malignancies in lymph nodes. The experimental measurements presented here give an indication of the sampling volume of the Raman needle probe in lymphoid tissues. Liquid tissue phantoms were used that contained scattering medium encompassing a range of scattering properties similar to those of a variety of tissue types, including lymph node tissues. To validate the appropriateness of the phantoms, the sampling depth of the probe was also measured in excised lymph node tissue. More than 50 % of Raman photons collected were found to originate from between the tip of the needle and a depth of 500 μm into the tissue. The needle probe presented here achieves spectral quality comparable to that in numerous studies previously demonstrating Raman disease discrimination. It is expected that this approach could achieve targeted subcutaneous tissue measurements and be viable for use for the in vivo Raman diagnostics of solid organs located within a few centimetres below the skin's surface. Graphical Abstract Schematic of multi-fibre Raman needle probe with disposible tips and proximal optical filtration.
authors.affiliation: Biomedical Physics, School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK.|Interface Analysis Centre, H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.
authors.forename: Ingeborg E
authors.initials: IE
authors.lastname: Iping Petterson
authors.affiliation: Interface Analysis Centre, H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.
authors.forename: John C C
authors.initials: JC
authors.lastname: Day
authors.affiliation: Biomedical Physics, School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK.|Biophotonics Research Unit, Gloucestershire Hospitals NHS Foundation Trust, Great Western Road, Gloucester, GL1 3NN, UK.
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Fullwood
authors.affiliation: Biomedical Physics, School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gardner
authors.affiliation: Biomedical Physics, School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK. N.stone@exeter.ac.uk.|Biophotonics Research Unit, Gloucestershire Hospitals NHS Foundation Trust, Great Western Road, Gloucester, GL1 3NN, UK. N.stone@exeter.ac.uk.
authors.forename: Nick
authors.initials: N
authors.lastname: Stone
mesh_terms: D004867:Equipment Design; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000175:diagnosis* / Q000473:pathology; D009339:Needles; D009369:Neoplasms / Q000175:diagnosis* / Q000473:pathology; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*
keywords: Diagnostics; Lymph nodes; Needle; Non-invasive; Raman spectroscopy