Dr. Nikola Krstajic Profile

Dr. Nikola Krstajic

Reader in Biomedical Engineering at Univ of Dundee

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Author

Publications (18)

Proceedings Article | 4 March 2022 Presentation + Paper

Simultaneous white light and laser speckle contrast imaging for in-vivo blood flow imaging during laparoscopic surgery: an alternative to fluorescence-based endoscopy

Ranjeet Kumar, Rodney Gush, Colin Murdoch, Nikola Krstajić

Proceedings Volume 11937, 1193702 (2022) https://doi.org/10.1117/12.2610332

KEYWORDS: Laparoscopy, Laser speckle contrast imaging, Surgery, Blood circulation, Prototyping, Endoscopes, Light emitting diodes, Blood, Speckle

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SPIE Journal Paper | 10 July 2018 Open Access

Low-cost high sensitivity pulsed endomicroscopy to visualize tricolor optical signatures

Nikola Krstajić, Bethany Mills, Ian Murray, Adam Marshall, Dominic Norberg, Thomas Craven, Philip Emanuel, Tushar Choudhary, Gareth O. Williams, Emma Scholefield, Ahsan Akram, Andrew Davie, Nik Hirani, Annya Bruce, Anne Moore, Mark Bradley, Kevin Dhaliwal

JBO, Vol. 23, Issue 07, 076005, (July 2018) https://doi.org/10.1117/12.10.1117/1.JBO.23.7.076005

KEYWORDS: Lung, Endomicroscopy, Luminescence, Tissues, Near infrared, Imaging systems, In vivo imaging, Light emitting diodes, Bacteria, Cameras

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Proceedings Article | 24 May 2018 Presentation

Multispectral fibre endoscope imaging system for enhanced visualisation of smartprobes (Conference Presentation)

Helen Parker, James Stone, Tom Speight, Robert Thomson, Kevin Dhaliwal, Nikola Krstajić, Michael Tanner

Proceedings Volume 10685, 106852Q (2018) https://doi.org/10.1117/12.2307563

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This talk will describe ratiometric imaging that can enhance visualisation of imaging probes against tissue autofluorescence. The Proteus project (www.proteus.ac.uk) aims to improve the detection and diagnosis of pulmonary infection and inflammation by employing targeted fluorescent molecules (Smartprobes) for labelling specific pathologies in tissue. However, imaging Smartprobes using a widefield fibred imaging system within the human lung can be challenging, in part, because both lung tissue and imaging probes have broad and overlapping emission spectra.. Weak signals from pathogens labelled with probes are easily missed due to the strong autofluorescent signatures of elastin and collagen that are abundantly present in the human lung. In addition to resolving probes from intrinsic fluorescence, multiple probes may have overlapping emission spectra themselves. This is particularly true for many well-established fluorophores that reside in the green region of the spectrum. If imaging with fluorophores that have distinct emission spectra is not possible or desirable, then spectral sorting of the signals can be carried out. To successfully resolve probes from healthy tissue or to resolve similar probes from each other, acquiring full spectral information is not necessarily a requirement. We describe a simple widefield fibred imaging system consisting of a single colour LED illumination source (480nm) that enables ratiometric methods to enhance contrast between different fluorescent sources. Fluorescence from 480nm excitation of tissue as well as Smartprobes present on the tissue is split into two optical paths, above and below a cut-off wavelength, by a dichroic mirror. A triggered system of a monochrome CMOS camera and optical chopper allows collection of dual images of the same field of view from different parts of the spectrum. Contrast enhancement is carried out by post processing of the images, enabling us to interpret better the images produced both in autofluorescence and molecular imaging contexts. Our widefield fibred imaging system is enabled by a novel optical fibre bundle developed by the University of Bath. The imaging fibres consist of 8100 cores with a 450µm corner to corner field of view and allows for multiplexed visualisation of pathologies within the lung. Biological targets, such as bacteria, that are of interest to clinicians, occupy one or two cores within the imaging fibre. We use 6µm Inspeck microspheres to demonstrate that the technique is shown to be able to distinguish targets analogous to bacteria. Also presented and demonstrated, is imaging and enhanced contrast of a biological model of labelled cells.

Proceedings Article | 17 May 2018 Presentation + Paper

Time-resolved single photon spectroscopy through a single optical fibre for miniaturised medical probe design

K. Ehrlich, H. Fleming, S. McAughtrie, A. Kufcsák, N. Krstajić, C. Campbell, R. Henderson, K. Dhaliwal, R. Thomson, M. Tanner

Proceedings Volume 10685, 106850Q (2018) https://doi.org/10.1117/12.2307334

KEYWORDS: Raman spectroscopy, Spectroscopy, Sensors, Optical fibers, Luminescence, Photons, Raman scattering, Single photon, Time metrology, CMOS sensors

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Proceedings Article | 20 February 2018 Paper

Time-zoomable FRET spectroscopy with a 512 x16 SPAD line sensor

Ahmet Erdogan, Gareth O. Williams, Andrea Usai, Nikola Krstajic, Neil Finlayson, Andrew Beavil, Rebecca Beavil, Robert Henderson

Proceedings Volume 10504, 105040M (2018) https://doi.org/10.1117/12.2290058

KEYWORDS: Fluorescence resonance energy transfer, Sensors, Luminescence, Single photon, Time resolved spectroscopy, CMOS sensors, Spectroscopy, Molecules, Molecular energy transfer, Time correlated photon counting

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Proceedings Article | 19 April 2017 Presentation

Multiplexed wavelength-to-time conversion of multimode light (Conference Presentation)

Harikumar Chandrasekharan, Frauke Izdebski, Itandehui Gris-Sánchez, Nikola Krstajić, Richard Walker, Helen Bridle, Paul Dalgarno, William MacPherson, Robert Henderson, Timothy Birks, Robert Thomson

Proceedings Volume 10106, 101060E (2017) https://doi.org/10.1117/12.2252482

KEYWORDS: Quantum optics, Waveguides, Single photon, Multiplexing, Fiber Bragg gratings, Sensors, Image resolution, Picosecond phenomena, Raman spectroscopy, LIDAR

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Proceedings Article | 28 February 2017 Paper

Fibre optic time-resolved spectroscopy using CMOS-SPAD arrays

K. Ehrlich, A. Kufcsák, N. Krstajić, R. Henderson, R. Thomson, M. Tanner

Proceedings Volume 10058, 100580H (2017) https://doi.org/10.1117/12.2252090

KEYWORDS: Time resolved spectroscopy, Sensors, Luminescence, Detector development, Environmental sensing, Single photon, Fiber optics, Optical fibers, Spectrographs, Tissue optics, CMOS sensors, Tissues, In vivo imaging

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SPIE Journal Paper | 27 April 2016 Open Access

Two-color widefield fluorescence microendoscopy enables multiplexed molecular imaging in the alveolar space of human lung tissue

Nikola Krstajić, Ahsan Akram, Tushar Choudhary, Neil McDonald, Michael Tanner, Ettore Pedretti, Paul Dalgarno, Emma Scholefield, John Girkin, Anne Moore, Mark Bradley, Kevin Dhaliwal

JBO, Vol. 21, Issue 04, 046009, (April 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.4.046009

KEYWORDS: Luminescence, Lung, Tissues, Cameras, Bacteria, Video, Imaging systems, Light emitting diodes, Optical filters, Multiplexing

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Proceedings Article | 17 June 2013 Paper

Improving TCSPC data acquisition from CMOS SPAD arrays

Nikola Krstajić, Simon Poland, David Tyndall, Richard Walker, Simao Coelho, David Li, Justin Richardson, Simon Ameer-Beg, Robert Henderson

Proceedings Volume 8797, 879709 (2013) https://doi.org/10.1117/12.2032807

KEYWORDS: Cameras, Fluorescence lifetime imaging, Microscopes, Luminescence, Sensors, Field programmable gate arrays, Laser scanners, Data acquisition, Single photon, Image resolution

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Proceedings Article | 22 February 2013 Paper

Development of a fast TCSPC FLIM-FRET imaging system

Simon Poland, Simao Coelho, Nikola Krstajić, David Tyndall, Richard Walker, James Monypenny, David Li, Robert Henderson, Simon Ameer-Beg

Proceedings Volume 8588, 85880X (2013) https://doi.org/10.1117/12.2004199

KEYWORDS: Fluorescence resonance energy transfer, Fluorescence lifetime imaging, Spatial light modulators, Luminescence, Sensors, Imaging systems, Microscopes, Cancer, Multiphoton microscopy, Single photon

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Proceedings Article | 22 February 2013 Paper

Multifocal multiphoton microscopy with adaptive optical correction

Simao Coelho, Simon Poland, Nikola Krstajic, David Li, James Monypenny, Richard Walker, David Tyndall, Tony Ng, Robert Henderson, Simon Ameer-Beg

Proceedings Volume 8588, 858817 (2013) https://doi.org/10.1117/12.2000188

KEYWORDS: Fluorescence lifetime imaging, Adaptive optics, Spatial light modulators, Multiphoton microscopy, Microscopy, Photons, Holograms, Optical calibration, Luminescence, Avalanche photodiodes

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SPIE Journal Paper | 15 May 2012 Open Access

Tissue surface as the reference arm in Fourier domain optical coherence tomography

Nikola Krstajic, Christian Brown, Kishan Dholakia, Mario Giardini

JBO, Vol. 17, Issue 7, 071305, (May 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.7.071305

KEYWORDS: Optical coherence tomography, Natural surfaces, Skin, Tissues, Tissue optics, Charge-coupled devices, Reflectivity, Reflection, Image processing, Aluminum

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Proceedings Article | 30 January 2012 Paper

Self-assembled quantum dot-based swept laser source for optical coherence tomography applications

N. Peyvast, D. T. D. Childs, N. Krstajic, Z. Lu, S. Matcher, D. Livshits, A. Shkolnik, I. Krestnikov, R. Hogg

Proceedings Volume 8213, 821336 (2012) https://doi.org/10.1117/12.907977

KEYWORDS: Optical coherence tomography, Quantum wells, Laser sources, Gallium arsenide, Optical filters, Laser systems engineering, Superluminescent sources, Neodymium, Quantum dots, Amplifiers

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Proceedings Article | 1 June 2011 Paper

Evaluation of a swept-laser optical coherence tomography light source based on a novel quantum-dot based semiconductor optical amplifier

Nik Krstajic, David Childs, Negin Peyvast, Deepa Kasaragod, Stephen Matcher, Igor Krestnikov, Richard Hogg

Proceedings Volume 8091, 80911S (2011) https://doi.org/10.1117/12.889247

KEYWORDS: Optical coherence tomography, Skin, Light sources, Semiconductor optical amplifiers, Diffraction gratings, Tissues, Image resolution, Imaging systems, Sensors, Tunable lasers

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Proceedings Article | 12 February 2011 Paper

Common path FDOCT based on multiple reflections within the sample arm

Nikola Krstajić, Richard Hogg, Stephen Matcher

Proceedings Volume 7889, 78892K (2011) https://doi.org/10.1117/12.874669

KEYWORDS: Reflectivity, Optical coherence tomography, Reflection, Interferometers, Microscopes, Charge-coupled devices, Optical fibers, Spectroscopy, Collimators, Skin

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Proceedings Article | 14 July 2009 Paper

Evaluation of a cheap ultrasonic stage for light source coherence function measurement, optical coherence tomography, optical coherence microscopy, and dynamic focusing

Nikola Krstajić, Stephen Matcher, David Childs, Wiendelt Steenbergen, Richard Hogg, Rod Smallwood

Proceedings Volume 7372, 73721I (2009) https://doi.org/10.1117/12.831787

KEYWORDS: Optical coherence tomography, Ultrasonics, Mirrors, Coherence (optics), Confocal microscopy, Point spread functions, Optical coherence microscopy, Light sources, Optical testing, Modulation

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Proceedings Article | 30 December 2008 Paper

Ex vivo and in vivo OCT image contrast

N. Krstajić, J. Jacobs, M. Bonesi, L. Smith, P. Deshpande, S. MacNeil, R. Smallwood, S. Matcher

Proceedings Volume 7139, 71390W (2008) https://doi.org/10.1117/12.819495

KEYWORDS: Optical coherence tomography, Skin, Bone, Cornea, Birefringence, In vivo imaging, Tissues, Tissue optics, Tissue engineering, Coherence (optics)

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Proceedings Article | 1 June 2005 Paper

Parallel beam optical tomography apparatus for 3D radiation dosimetry

Nikola Krstajic, Simon Doran

Proceedings Volume 5823, (2005) https://doi.org/10.1117/12.604973

KEYWORDS: Charge-coupled devices, Collimation, Optical tomography, Scattering, Spatial resolution, Radiotherapy, Refractive index, Light sources, Magnetic resonance imaging, Laser scattering

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Showing 5 of 18 publications

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