A review of career devoted to biophotonics-in memoriam to Ekaterina Borisova (1978-2021)

Regretfully, because of her sudden demise, Assoc. Prof. Ekaterina Borisova is no longer amongst us. COVID-19 pulled away a brilliant scientist during the peak of her scientific career (see Fig. 1). All authors would like to express deepest condolences and sincere support to her family, friends, relatives and colleagues! We, therefore, rightfully commemorate her dedicated and devoted contribution to biophotonics, her readiness to always support, help, motivate and inspire all her colleagues and collaborators

Validation of a software platform for 2D and 3D phase contrast imaging: Preliminary subjective evaluation

A complete software platform based on anthropomorphic breast models used with both planar and three-dimensional phase contrast breast imaging is presented and subjectively validated. For the development of the platform, tests with three anthropomorphic breast phantoms, available both in computational and physical form, were designed and implemented. The models are characterized with different complexity: two phantoms are with spheres and one anthropomorphic. Further on, two of the physical breast models were created with the use of 3D printing techniques. These phantoms with thickness of 40 mm and 31 mm, respectively, were based on digital phantoms created with in-house developed software tools. The third physical breast phantom is the L1 phantom developed at Katholieke Universiteit Leuven with 58 mm thickness. Based on this physical phantom, a computational one was created. The three physical breast phantoms were imaged at ID17 biomedical imaging line at ESRF. Two acquisition setups were used: planar and limited angle tomography modes. Simulated and experimental planar and three-dimensional images were compared in terms of visual reproducibility. Results showed that phantoms characterized with more simple structure produce subjectively similar experimental and simulation appearance in terms of object reproduction and similar edge effects. The thicker phantom demonstrated lower visual coincidence between the two types of planar images, due to higher thickness and higher energy incident beam. The results of this study will be used in the design of new experimental study, to be conducted at lower incident beam energy as well as improving the modelling of phase contrast imaging by using Monte Carlo techniques

An integrated research tool for X-ray imaging simulation

This paper presents a software simulation package of the entire X-ray projection radiography process including beam generation, absorber structure and composition, irradiation set up, radiation transport through the absorbing medium, image formation and dose calculation. Phantoms are created as composite objects from geometrical or voxelized primitives and can be subjected to simulated irradiation process. The acquired projection images represent the two-dimensional spatial distribution of the energy absorbed in the detector and are formed at any geometry, taking into account energy spectrum, beam geometry and detector response. This software tool is the evolution of a previously presented system, with new functionalities, user interface and an expanded range of applications. This has been achieved mainly by the use of combinatorial geometry for phantom design and the implementation of a Monte Carlo code for the simulation of the radiation interaction at the absorber and the detector. © 2002 Published b

A hybrid simulation framework for computer simulation and modelling studies of grating-based x-ray phase-contrast images

Clinical studies performed using computer simulation are inexpensive, flexible methods that can be used to study aspects of a proposed imaging technique prior to a full clinical study. Typically, lesions are simulated into (experimental) data to assess the clinical potential of new methods or algorithms. In grating-based phase-contrast imaging (GB-PCI), full wave simulations are, however, computationally expensive due to the high periodicity of the gratings and therefore not practically applicable when large data sets are required. This work describes the development of a hybrid modelling platform that combines analytical and empirical input data for a more rapid simulation of GB-PCI images with little loss of accuracy. Instead of an explicit implementation of grating details, measured summary metrics (i.e. visibility, flux, noise power spectra, presampling modulation transfer function) are applied in order to generate transmission and differential phase images with large fields of view. Realistic transmission and differential phase images were obtained with good quantitative accuracy. The different steps of the simulation framework, as well as the methods to measure the summary metrics, are discussed in detail such that the technique can be easily customized for a given system. The platform offers a fast, accurate alternative to full wave simulations when the focus switches from grating/system design and set up to the generation of GB-PCI images for an established system.status: publishe

Evaluation of an improved algorithm for producing realistic 3D breast software phantoms: application for mammography

PURPOSE: This work presents an improved algorithm for the generation of 3D breast software phantoms and its evaluation for mammography. METHODS: The improved methodology has evolved from a previously presented 3D noncompressed breast modeling method used for the creation of breast models of different size, shape, and composition. The breast phantom is composed of breast surface, duct system and terminal ductal lobular units, Cooper\u27s ligaments, lymphatic and blood vessel systems, pectoral muscle, skin, 3D mammographic background texture, and breast abnormalities. The key improvement is the development of a new algorithm for 3D mammographic texture generation. Simulated images of the enhanced 3D breast model without lesions were produced by simulating mammographic image acquisition and were evaluated subjectively and quantitatively. For evaluation purposes, a database with regions of interest taken from simulated and real mammograms was created. Four experienced radiologists participated in a visual subjective evaluation trial, as they judged the quality of the simulated mammograms, using the new algorithm compared to mammograms, obtained with the old modeling approach. In addition, extensive quantitative evaluation included power spectral analysis and calculation of fractal dimension, skewness, and kurtosis of simulated and real mammograms from the database. RESULTS: The results from the subjective evaluation strongly suggest that the new methodology for mammographic breast texture creates improved breast models compared to the old approach. Calculated parameters on simulated images such as beta exponent deducted from the power law spectral analysis and fractal dimension are similar to those calculated on real mammograms. The results for the kurtosis and skewness are also in good coincidence with those calculated from clinical images. Comparison with similar calculations published in the literature showed good agreement in the majority of cases. CONCLUSIONS: The improved methodology generated breast models with increased realism compared to the older model as shown in evaluations of simulated images by experienced radiologists. It is anticipated that the realism will be further improved using an advanced image simulator so that simulated images may be used in feasibility studies in mammography

THE NEW FACE OF VITAMIN K - MORE THAN BLOOD CLOTTING FACTOR

Introduction: Twenty years ago, the metabolism of vitamin K was connected with its role in hemostasis. Since that time, it has been shown that vitamin K exerts multiple functions mediated by the Gla-proteins, having vitamin K as a cofactor. Numerous publications affirm that these Gla-proteins are related to physiological processes beyond coagulations, such as bone metabolism, vascular health and energy homeostasis.Aim: The aim of this research is to provide new data for the role of vitamin K in a myriad of physiological processes beyond blood clotting. Additionally, it aims to assess the potential new applications of vitamin K as a supplement for the prevention of bone and vascular diseases.Materials and Methods: Using the online databases Scopus, PubMed and Google Scholar, a search with the keywords: `vitamin K2`, `bone metabolism`, `cardiovascular diseases`, `osteocalcin` and `MGP` was conducted. Information regarding the effects of vitamin K on bone and vascular health was referred to in this work.Results: Vitamin K and vitamin K-dependent proteins play pivotal roles in the physiology of bone mineralization and in preventing ectopic calcification. Osteocalcin, a Gla protein located in bone and dentin, is important for bone mineralization. Following the posttranslational carboxylation of Glu-residues with a cofactor vitamin K2 (menaquinone), rather than vitamin K1 (phylloquinone), osteocalcin shows increased affinity for calcium. Osteocalcin is believed to be involved in osteoblast regulation and hydroxyapatite crystal growth. Matrix GLa-protein (MGP), sharing some sequences with osteocalcin, is a local inhibitor of arterial calcification. Vitamin K deficiency impairs the function of osteocalcin and MGP and, therefore, presumably contributes to bone demineralization and vascular calcification, the so-called calcium paradox.Conclusions: Vitamin K deficiencies, traditionally regarded as a cause for internal hemorrhages and blood clotting disorders, apparently can be linked to cardiovascular calcification and abnormal bone modelling. Appropriate treatment of vitamin K deficiency may improve bone and arterial health

Evaluation of the BreastSimulator software platform for breast tomography: Preliminary results

The aim of this work is the evaluation of the software BreastSimulator, as a tool for the creation of 3D uncompressed breast digital models and for the simulation and the optimization of Computed Tomography (CT) equipment. Three 3D digital breast phantoms were created, having different sizes and with realistic anatomical features. We calculated 2D X-ray CT projections simulating a breast tomogram with a dedicated cone-beam CT scanner. From the reconstructed CT slices, the power-law exponent, has been evaluated from the Noise Power Spectrum function S(f) = α/fβ. The results were then verified by comparison against clinical CT and published data. The preliminary results of this study showed that the simulated model complexity may reproduce the real anatomical complexity of the breast tissues as described, in terms of β values, since the measured β coefficients are close to that of clinical CT data from a dedicated breast CT scanner.The final publication is available at https://link.springer.com/chapter/10.1007/978-3-319-41546-8_1

Comparisons of glandular breast dose between digital mammography, tomosynthesis and breast CT based on anthropomorphic patient-derived breast phantoms

Purpose: To evaluate the bias to the mean glandular dose (MGD) estimates introduced by the homogeneous breast models in digital breast tomosynthesis (DBT) and to have an insight into the glandular dose distributions in 2D (digital mammography, DM) and 3D (DBT and breast dedicated CT, BCT) x-ray breast imaging by employing breast models with realistic glandular tissue distribution and organ silhouette. Methods: A Monte Carlo software for DM, DBT and BCT simulations was adopted for the evaluation of glandular dose distribution in 60 computational anthropomorphic phantoms. These computational phantoms were derived from 3D breast images acquired via a clinical BCT scanner. Results: g·c·s·T conversion coefficients based on homogeneous breast model led to a MGD overestimate of 18% in DBT when compared to MGD estimated via anthropomorphic phantoms; this overestimate increased up to 21% for recently computed DgNDBT conversion coefficients. The standard deviation of the glandular dose distribution in BCT resulted 60% lower than in DM and 55% lower than in DBT. The glandular dose peak – evaluated as the average value over the 5% of the gland receiving the highest dose – is 2.8 times the MGD in DM, this factor reducing to 2.6 and 1.6 in DBT and BCT, respectively. Conclusions: Conventional conversion coefficients for MGD estimates based on homogeneous breast models overestimate MGD by 18%, when compared to MGD estimated via anthropomorphic phantoms. The ratio between the peak glandular dose and the MGD is 2.8 in DM. This ratio is 8% and 75% higher than in DBT and BCT, respectively