Dr Lucia Florescu
About
Biography
Lucia Florescu joined the University of Surrey in 2017 as a Lecturer in Medical Imaging and Wellcome Trust Fellow. Prior to joining Surrey, she worked in research and development at Elekta, acting as a Lead Physicist on the conception, development and implementation of cutting-edge technologies for image-guided radiation therapy and image-based radiation dosimetry. Prior to this, she was an Associate Research Scientist at Columbia University, a Research Associate at the University of Pennsylvania, a US Academy of Sciences (NRC) scholar at NASA Jet Propulsion Laboratory, California Institute of Technology, and a California Nano-Systems Institute & Hewlett Packard postdoctoral scholar at the University of California Los Angeles. She has received her PhD in Physics from the University of Toronto.
Her research focuses on developing a fundamental understanding of the interaction between radiation and biological tissue and exploiting this to devise new techniques and image reconstruction algorithms for advanced biomedical tomographic imaging.
ResearchResearch interests
- Optical Tomography, Computed Tomography, Cone-Beam CT, Photoacoustic Imaging, Scatter Tomography, Positron Emission Tomography
- Inverse problems, interior tomography, radiation transport, AI, iterative image reconstruction
- Image guided radiation therapy, optical-CT gel dosimetry.
I am actively recruiting PhD students for a number of projects, including:
- Polarisation-sensitive optical tomography
- Deep learning for advanced tomographic reconstruction and image-guided radiation therapy
- Cherenkov emission based optical tomography for functional image guided radiation therapy.
For more information, please contact me at l.m.florescu@surrey.ac.uk.
Research interests
- Optical Tomography, Computed Tomography, Cone-Beam CT, Photoacoustic Imaging, Scatter Tomography, Positron Emission Tomography
- Inverse problems, interior tomography, radiation transport, AI, iterative image reconstruction
- Image guided radiation therapy, optical-CT gel dosimetry.
I am actively recruiting PhD students for a number of projects, including:
- Polarisation-sensitive optical tomography
- Deep learning for advanced tomographic reconstruction and image-guided radiation therapy
- Cherenkov emission based optical tomography for functional image guided radiation therapy.
For more information, please contact me at l.m.florescu@surrey.ac.uk.
Supervision
Postgraduate research supervision
PhD student supervision
- William Vale " Artificial Intelligence for Improving Photoacoustic Imaging for CAR-T Cell Cancer Therapy ", NPL iCASE EPSRC studentship" (2023- present).
- Nicholas Leybourne "Digital Positron Emission Tomography and Its Application to Radiation Therapy Dose Painting" (2022-present).
- Clara Leboreiro Babe (with Prof. Jeff Bamber, ICR), "Photoacoustic imaging for the optimisation of CAR-T cell cancer therapy of soft-tissue tumours: gene expression studies” (2021-present).
- Jigar Dubal, "Optical Tomography for Functional Image Guided Radiation Therapy" (2019-present).
- Matthew Faulkner, "Nonreciprocal Broken-Ray Tomography" (2018-present).
MSc project supervision
- Kashyap Hebbar, Deep Learning for Advanced CBCT Reconstruction for Image-Guided Radiation Therapy (2023).
- Shubham Gogri, Deep Learning for Image Improvement in Sparse-View CT (2023).
- Priyam Soni, "Deep learning for CT reconstruction with incomplete data" (2022).
- Martin Wormwell "Cherenkov light based dosimetry of molecular radiation therapy" (2022).
- Sayorn Thangarajah, "CBCT reconstruction with incomplete data" (2022).
Undergraduate Project supervision
- Mohammed Al-Thani, Fan-beam CT reconstruction with incomplete data (2020-2021).
- Elley Bridges, "Interior Tomography" (2019-2020).
- Matthew Faulkner, "Optical CT reconstruction based on incomplete data: applications to radiation dosimetry" (2017-2018).
Teaching
- Lecturer: EEE1033 Computer and Digital Logic
- Personal Tutor for undergraduate students.
Publications
Broken ray transforms (BRTs) are typically considered to be reciprocal, meaning that the transform is independent of the direction in which a photon travels along a given broken ray. However, if the photon can change its energy (or be absorbed and re-radiated at a different frequency) at the vertex of the ray, then reciprocity is lost. In optics, non-reciprocal BRTs are applicable to imaging problems with fluorescent contrast agents. In the case of x-ray imaging, problems with single Compton scattering also give rise to non-reciprocal BRTs. In this paper, we focus on tomographic optical fluorescence imaging and show that, by reversing the path of a photon and using the non-reciprocity of the data function, we can reconstruct simultaneously and independently all optical properties of the medium (the intrinsic attenuation coefficients at the excitation and the fluorescence frequency and the concentration of the contrast agent). Our results are also applicable to inverting BRTs that arise due to single Compton scattering.
Numerical experiments were performed to analyse the effect of data loss at the edges of the sample on the accuracy of optical-CT reconstruction, in the context of applications to radiation dosimetry.
We address the interior problem of computed tomography that occurs when projection data is only available for a region in the interior of the sample. In this case, it is not possible to accurately reconstruct the attenuation function even in the interior domain. We consider an algorithm for correcting the interior tomography reconstruction which is based on prior knowledge in the interior domain. This correction algorithm is evaluated by performing numerical experiments with the Shepp-Logan phantom for various amounts of data loss, noise in the available projection data, various values of the attenuation function known a priori, and various positions within the sample where the prior information is available. Good performance of the algorithm based on prior knowledge at one point is demonstrated in the case of noiseless data. In the presence of noise in the projection data, improvements in the reconstructed attenuation function are obtained based on prior knowledge at a number of points in the interior domain. The robustness of the correction algorithm to errors in the values of the attenuation function used as prior knowledge was also investigated.
We present a tomographic imaging technique based on angularly-selective measurements of fluorescent light that enables for the first time simultaneous reconstruction of the attenuation coefficient at two energies and of the contrast-agent concentration.
Optical methods of biomedical tomographic imaging are of considerable interest due to their non-invasive nature and sensitivity to physiologically important markers. Similarly to other imaging modalities, optical methods can be enhanced by utilizing extrinsic contrast agents. Typically, these are fluorescent molecules, which can aggregate in regions of interest due to various mechanisms. In the current approaches to imaging, the intrinsic (related to the tissue) and extrinsic (related to the contrast agent) optical parameters are determined separately. This can result in errors, in particular, due to using simplified heuristic models for the spectral dependence of the optical parameters. Recently, we have developed the theory of non-reciprocal broken-ray tomography (NRBRT) for fluorescence imaging of weakly scattering systems. NRBRT enables simultaneous reconstruction of the fluorophore concentration as well as of the intrinsic optical attenuation coefficient at both the excitation and the emission wavelengths. Importantly, no assumption about the spectral dependence of the tissue optical properties is made in NRBRT. In this study, we perform numerical validation of NRBRT under realistic conditions using the Monte Carlo method to generate forward data. We demonstrate that NRBRT can be used for tomographic imaging of samples of up to four scattering lengths in size. The effects of physical characteristics of the detectors such as the area and the acceptance angle are also investigated.
We perform numerical experiments based on Monte Carlo simulations and clinical CT data to investigate Cherenkov light emission in molecular radiation therapy of hyperthyroidism, and demonstrate that Cherenkov light-based dosimetry could be feasible.
Numerical experiments based on Monte Carlo simulations and clinical CT data are performed to investigate the spatial and spectral characteristics of Cherenkov light emission and the relationship between Cherenkov light intensity and deposited dose in molecular radiotherapy of hyperthyroidism and papillary thyroid carcinoma. It is found that Cherenkov light is emitted mostly in the treatment volume, the spatial distribution of Cherenkov light at the surface of the patient presents high-value regions at locations that depend on the symmetry and location of the treatment volume, and the surface light in the near-infrared spectral region originates from the treatment site. The effect of inter-patient variability in the tissue optical parameters and radioisotope uptake on the linear relationship between the dose absorbed by the treatment volume and Cherenkov light intensity at the surface of the patient is investigated, and measurements of surface light intensity for which this effect is minimal are identified. The use of Cherenkov light measurements at the patient surface for molecular radiation therapy dosimetry is also addressed.