Ji Qi

Ji Qi
Imperial College London | Imperial · Division of Surgery

PhD

About

27
Publications
5,288
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596
Citations

Publications

Publications (27)
Article
Full-text available
The contrast mechanism of medical endoscopy is mainly based on metrics of optical intensity and wavelength. As another fundamental property of light, polarization can not only reveal tissue scattering and absorption information from a different perspective, but can also provide insight into directional tissue birefringence properties to monitor pat...
Article
Full-text available
Mueller matrix polarimetric imaging has shown potential in tissue diagnosis but is challenging to implement endoscopically. In this work, a narrow band 3 × 3 Mueller matrix polarimetric endoscope was designed by rotating the endoscope to generate 0°, 45° and 90° linearly polarized illumination and positioning a rotating filter wheel in front of the...
Article
Full-text available
Polarization is a fundamental property of light and a powerful sensing tool that has been applied to many areas. A Mueller matrix is a complete mathematical description of the polarization characteristics of objects that interact with light, and is known as a transfer function of Stokes vectors which characterise the state of polarization of light....
Article
The polar decomposition method for Mueller matrices proposed by Lu–Chipman has been demonstrated and validated for many applications. However, in some situations, e.g., when analyzing the Mueller matrix of birefringent turbid media with Mie-sized scatterers acquired in reflection geometry, the method may suffer from limitations due to the assumptio...
Article
Tissue depolarization and linear retardance are the main polarization characteristics of interest for bulk tissue characterization, and are normally interpreted from Mueller polarimetry. Stokes polarimetry can be conducted using simpler instrumentation and in a shorter time. Here we use Stokes polarimetric imaging with circularly polarized illumina...
Article
Full-text available
Smoke generated during surgery affects tissue visibility and degrades image quality, affecting surgical decisions and limiting further image processing and analysis. Polarization is a fundamental property of light and polarization-resolved imaging has been studied and applied to general visibility restoration scenarios such as for smog or mist remo...
Article
Full-text available
Advances in vectorial polarization-resolved imaging are bringing new capabilities to applications ranging from fundamental physics through to clinical diagnosis. Imaging polarimetry requires determination of the Mueller matrix (MM) at every point, providing a complete description of an object's vectorial properties. Despite forming a comprehensive...
Preprint
Full-text available
Advances in vectorial polarisation-resolved imaging are bringing new capabilities to applications ranging from fundamental physics through to clinical diagnosis. Imaging polarimetry requires determination of the Mueller matrix (MM) at every point, providing a complete description of an object's vectorial properties. Despite forming a comprehensive...
Preprint
Full-text available
While polarisation sensing is vital in many areas of research, with applications spanning from microscopy to aerospace, traditional approaches are limited by method-related error amplification or accumulation, placing fundamental limitations on precision and accuracy in single-shot polarimetry. Here, we put forward a new measurement paradigm to cir...
Article
Full-text available
3×3 Mueller polarimetry has shown potential for tissue characterization applications, however, calibration has not been fully addressed. We demonstrate a 3×3 Mueller polarimeter eigenvalue calibration method, inspired by those for full Mueller polarimeters. We also investigate the optimal combination of calibration measurements. Our method does not...
Article
Full-text available
Mueller matrix polarimetry is a potentially powerful technique for obtaining microstructural information of biomedical specimens. Thus, it has found increasing application in both backscattering imaging of bulk tissue samples and transmission microscopic imaging of thin tissue slices. Recently, we proposed a technique to transform the 4 × 4 Mueller...
Article
Full-text available
Tissue polarimetric imaging measures Mueller matrices of tissues or Stokes vectors of the emergent light from tissues (normally using incidence with a fixed polarization state) over a field of view, and has demonstrated utility in a number of surgical and diagnostic applications. Here we introduce a compact complete Stokes polarimetric imager that...
Conference Paper
Full-text available
Intra-operative measurements of tissue shape and multi/ hy-perspectral information have the potential to provide surgical guidance and decision making support. We report an optical probe based system to combine sparse hyperspectral measurements and spectrally-encoded structured lighting (SL) for surface measurements. The system provides informative...
Article
Full-text available
Polarization imaging has been recognized as a potentially powerful technique for probing the microstructural information and optical properties of complex biological specimens. Recently, we have reported a Mueller matrix microscope by adding the polarization state generator and analyzer (PSG and PSA) to a commercial transmission-light microscope, a...
Article
Intra-operative measurements of tissue shape and multi/ hyperspectral information have the potential to provide surgical guidance and decision making support. We report an optical probe based system to combine sparse hyperspectral measurements and spectrally-encoded structured lighting (SL) for surface measurements. The system provides informative...
Conference Paper
Tissue surface shape and reflectance spectra provide rich intra-operative information useful in surgical guidance. We propose a hybrid system which displays an endoscopic image with a fast joint inspection of tissue surface shape using structured light (SL) and hyperspectral imaging (HSI). For SL a miniature fibre probe is used to project a coloure...
Conference Paper
The mechanism of most medical endoscopes is based on the interaction between light and biological tissue, inclusive of absorption, elastic scattering and fluorescence. In essence, the metrics of those interactions are obtained from the fundamental properties of light as an electro-magnetic waves, namely, the radiation intensity and wavelength. As a...
Article
Polarisation imaging has the potential to provide enhanced contrast based on variations in the optical properties, such as scattering or birefringence, of the tissue of interest. Examining the signal at different wavebands in the visible spectrum also allows interrogation of different depths and structures. A stereo endoscope has been adapted to al...
Conference Paper
Mueller polarimetric imaging is a promising technique which is able to provide additional polarisation contrast for surgical imaging. In this work, improved 3×3 and 4×4 Mueller matrix endoscopic systems were constructed and tested with tissue samples.
Article
Full-text available
Elastic light scattering spectroscopy (LSS) is widely utilized to investigate cellular structures in cultured cells and various tissues. However, few imaging systems, especially endoscopic imaging systems, can implement LSS. It is the aim of this work to create a polarized multispectral imaging system based around a rigid endoscope to detect microm...
Article
Nanoparticles are viewed as a promising tool for numerous medical applications, for instance imaging and photothermal therapy (PTT) has been proposed using gold nanorods. We are developing multi-functional gold nanorods (m-GNRs) which have potential for image guided endoscopic surgery of tumour tissue with a modified laparoscope system. A new synth...
Article
A multi-spectral illumination approach for real-time mapping of the presence of gold nanoparticles in bulk tissue is presented. A Principal Component Analysis method is followed for determining the wavelengths that will make up the multispectral imaging endoscope.

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