Dr. Tushar R. Choudhary Profile

Dr. Tushar R. Choudhary

Research Fellow at Univ of Edinburgh

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Author

Publications (7)

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

Early arriving photon imaging for locating optical endomicroscopy fibres and medical devices (Conference Presentation)

Michael Tanner, Tushar Choudhary, Tom Craven, Bethany Mills, Mark Bradley, Robert Henderson, Kevin Dhaliwal, Robert Thomson

Proceedings Volume 10685, 106852E (2018) https://doi.org/10.1117/12.2307562

KEYWORDS: Light scattering, Optical imaging, Medical devices, Tissue optics, Biomedical optics, Endomicroscopy, Photonic devices, Endoscopes, Imaging devices, Image resolution

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Optical fibre based endoscopes are increasingly used for imaging and sensing within the human body without navigational guidance of the miniaturised fibre probe. Meanwhile, other medical device placement is a standard procedure in clinic. We demonstrate successful imaging of optical device location with centimetre resolution in clinically relevant models, in a realistically lit environment, achieved through the detection of early arriving photons with a time resolved single photon detector array. This prototype has been developed within the UK-EPSRC Proteus project, moving advanced research technologies towards clinical implementation. Short (~100ps) laser pulses are transmitted from the tip of the endoscope at 785nm in the “optical window” where attenuation is less severe in clinical scenarios. Most of the photons that pass through tissue undergo much scattering from the disordered tissue structures providing only low accuracy determination of the location of the light source. However, some photons probabilistically undergo less scattering, travelling through the medium in an almost straight line without a much extended path. Such photons exit the body sooner than the highly scattered light. A camera based upon a 32 × 32 array of Single Photon Avalanche Diodes (SPADs) made with CMOS technology is used to image the small number photons exiting the tissue. The time resolution capabilities of such a single photon detector (50ps time bin resolution, 200ps jitter) allow observation of the photon arrival times simultaneously for all 1024 pixels of the imaging array. Photon arrival statistics distinguish the early arriving photons from the highly scattered light, revealing the endoscope location. Scattered photon arrivals peak at delays of multiple nanoseconds due to the thick tissue samples. The progression of light through complex scattering structures can be observed. Normal fluorescent room lighting has distinct emission peaks. Appropriate choice of operating wavelength between these spectral features, combined with aggressive filtering, allows operation in normal fluorescent lighting. This compact packaged system is demonstrated in a normally lit room to determine optical endomicroscope location in a whole ventilated ovine lung as well as tissue models including bone structure. At the limit of capabilities of this prototype, demonstration through an entire human torso is shown to be possible. System improvements and the potential of the next generation prototype in development will be discussed. This offers the potential for real time (sub second) imaging of device location with a portable system for application in standard medical procedures, such as catheter insertion. The avoidance of the need to confirm device placement with X-ray imaging has potential to decrease disruption to procedures throughout clinical practice.

Proceedings Article | 14 March 2018 Presentation

A multifunctional endoscope for imaging, fluid delivery and fluid extraction (Conference Presentation)

James Stone, Tushar Choudhary, Helen Parker, Bethany Mills, Adam Marshall, Debaditya Choudhury, Michael Tanner, Harry Wood, Kerrianne Harrington, Jonathan Knight, Tim Birks, Kevin Dhaliwal, Mark Bradley

Proceedings Volume 10488, 104880V (2018) https://doi.org/10.1117/12.2289555

KEYWORDS: Endoscopes, Microfluidic imaging, Microfluidics, Endoscopy, Optical fibers, Telecommunications, Pathogens, Target detection, Lung, Tissues

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Proceedings Article | 19 April 2017 Presentation

Multiplexed fibre optic sensing in the distal lung (Conference Presentation)

Tushar Choudhary, Michael Tanner, Alicia Megia-Fernandez, Kerrianne Harrington, Harry Wood, Sunay Chankeshwara, Patricia Zhu, Debaditya Choudhury, Fei Yu, Robert Thomson, Rory Duncan, Kevin Dhaliwal, Mark Bradley

Proceedings Volume 10058, 100580E (2017) https://doi.org/10.1117/12.2249982

KEYWORDS: Fiber optics, Optical sensing, Oxygen, Sensors, Lung, Multiplexing, In vitro testing, Pathology, In vivo imaging, Palladium

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Proceedings Article | 19 April 2017 Presentation

Endoscopic sensing of pH in the distal lung (Conference Presentation)

Debaditya Choudhury, Michael Tanner, Sarah McAughtrie, Fei Yu, Bethany Mills, Tushar Choudhary, Sohan Seth, Thomas Craven, James Stone, Ioulia Mati, Colin Campbell, Mark Bradley, Christopher Williams, Kevin Dhaliwal, Timothy Birks, Robert Thomson

Proceedings Volume 10041, 100410B (2017) https://doi.org/10.1117/12.2251925

KEYWORDS: Medical research, Biosensing, Chemistry, Chronic obstructive pulmonary disease, Inflammation, Blood, Lung, Surface enhanced Raman spectroscopy, Physiology, Endoscopy

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Proceedings Article | 19 April 2017 Presentation

Towards in vivo bacterial detection in human lung (Conference Presentation)

Tushar Choudhary, Mark Bradley, Rory Duncan, Kevin Dhaliwal

Proceedings Volume 10041, 100410M (2017) https://doi.org/10.1117/12.2250536

KEYWORDS: In vivo imaging, Lung, Tissues, Fluorescence lifetime imaging, Luminescence, Microscopy, Tissue optics, Resistance, Diagnostics, Molecular 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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