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BACKGROUND AND OBJECTIVE: The development, control and optimisation of new x-ray breast imaging modalities could benefit from a quantitative assessment of the resulting image textures. The aim of this work was to develop a software tool for routine radiomics applications in breast imaging, which will also be available upon request. METHODS: The tool (developed in MATLAB) allows image reading, selection of Regions of Interest (ROI), analysis and comparison. Requirements towards the tool also included convenient handling of common medical and simulated images, building and providing a library of commonly applied algorithms and a friendly graphical user interface. Initial set of features and analyses have been selected after a literature search. Being open, the tool can be extended, if necessary. RESULTS: The tool allows semi-automatic extracting of ROIs, calculating and processing a total of 23 different metrics or features in 2D images and/or in 3D image volumes. Computations of the features were verified against computations with other software packages performed with test images. Two case studies illustrate the applicability of the tool - (i) features on a series of 2D 'left' and 'right' CC mammograms acquired on a Siemens Inspiration system were computed and compared, and (ii) evaluation of the suitability of newly proposed and developed breast phantoms for x-ray-based imaging based on reference values from clinical mammography images. Obtained results could steer the further development of the physical breast phantoms. CONCLUSIONS: A new image analysis toolbox was realized and can now be used in a multitude of radiomics applications, on both clinical and test images. ispartof: PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS vol:89 pages:114-128 ispartof: location:Italy status: published

Purpose We present the development and the current state of the MaXIMA Breast Lesions Models Database, which is intended to provide researchers with both segmented and mathematical computer-based breast lesion models with realistic shape. Methods The database contains various 3D images of breast lesions of irregular shapes, collected from routine patient examinations or dedicated scientific experiments. It also contains images of simulated tumour models. In order to extract the 3D shapes of the breast cancers from patient images, an in-house segmentation algorithm was developed for the analysis of 50 tomosynthesis sets from patients diagnosed with malignant and benign lesions. In addition, computed tomography (CT) scans of three breast mastectomy cases were added, as well as five whole-body CT scans. The segmentation algorithm includes a series of image processing operations and region-growing techniques with minimal interaction from the user, with the purpose of finding and segmenting the areas of the lesion. Mathematically modelled computational breast lesions, also stored in the database, are based on the 3D random walk approach. Results The MaXIMA Imaging Database currently contains 50 breast cancer models obtained by segmentation of 3D patient breast tomosynthesis images; 8 models obtained by segmentation of whole body and breast cadavers CT images; and 80 models based on a mathematical algorithm. Each record in the database is supported with relevant information. Two applications of the database are highlighted: inserting the lesions into computationally generated breast phantoms and an approach in generating mammography images with variously shaped breast lesion models from the database for evaluation purposes. Both cases demonstrate the implementation of multiple scenarios and of an unlimited number of cases, which can be used for further software modelling and investigation of breast imaging techniques. The created database interface is web-based, user friendly and is intended to be made freely accessible through internet after the completion of the MaXIMA project. Conclusions The developed database will serve as an imaging data source for researchers, working on breast diagnostic imaging and on improving early breast cancer detection techniques, using existing or newly developed imaging modalities.

Introduction: In X-ray imaging, test objects reproducing breast anatomy characteristics are realized to optimize issues such as image processing or reconstruction, lesion detection performance, image quality and radiation induced detriment. Recently, a physical phantom with a structured background has been introduced for both 2D mammography and breast tomosynthesis. A software version of this phantom and a few related versions are now available and a comparison between these 3D software phantoms and the physical phantom will be presented. Methods: The software breast phantom simulates a semi-cylindrical container filled with spherical beads of different diameters. Four computational breast phantoms were generated with a dedicated software application and for two of these, physical phantoms are also available and they are used for the side by side comparison. Planar projections in mammography and tomosynthesis were simulated under identical incident air kerma conditions. Tomosynthesis slices were reconstructed with an in-house developed reconstruction software. In addition to a visual comparison, parameters like fractal dimension, power law exponent β and second order statistics (skewness, kurtosis) of planar projections and tomosynthesis reconstructed images were compared. Results: Visually, an excellent agreement between simulated and real planar and tomosynthesis images is observed. The comparison shows also an overall very good agreement between parameters evaluated from simulated and experimental images. Conclusion: The computational breast phantoms showed a close match with their physical versions. The detailed mathematical analysis of the images confirms the agreement between real and simulated 2D mammography and tomosynthesis images. The software phantom is ready for optimization purpose and extrapolation of the phantom to other breast imaging techniques.

3D breast modelling for 2D and 3D breast x-ray imaging would benefit from the availability of digital and physical phantoms that reproduce accurately the complexity of the breast anatomy. While a number of groups have produced digital phantoms with increasing level of complexity, physical phantoms reproducing that software approach have been scarcely developed. One possibility is offered by 3D printing technology. This implies the assessment of the energy dependent absorption index β of 3D printing materials for absorption based imaging, as well as the assessment of the refractive index decrement, δ, of the printing material, for phase contrast imaging studies, at the energies of interest for breast imaging. In this work we set-up a procedure and performed a series of measurements (at 30, 45 and 60 keV, at the European Synchrotron Radiation Facility) for assessing the relative value of δ with respect to that of breast tissues, for twelve 3D printing materials. The method included propagation based phase contrast 2D imaging and retrieval of the estimated phase shift map, using the Paganin's algorithm. Breast glandular, adipose and skin tissues were used as reference materials of known ratio δ/β. A percentage difference Δδ was introduced to assess the suitability of the printing materials as tissue substitutes. The accuracy of the method (about 4%) was assessed based on the properties of PMMA and Nylon, acting as gold standard. Results show that, for the above photon energies, ABS is a good substitute for adipose tissue, Hybrid as a substitute of the glandular tissue and PET-G for simulating the skin. We plan to realize a breast phantom manufactured by fused deposition modelling (FDM) technology using ABS, Hybrid and PET-G as substitutes of the glandular and skin tissue and a second phantom by stereolithography (SLA) technology with the resins Flex, Tough and Black.

This paper presents a method for creation of computational models of breast lesions with irregular shapes from patient Digital Breast Tomosynthesis (DBT) images or breast cadavers and whole-body Computed Tomography (CT) images. The approach includes six basic steps: (a) normalization of the intensity of the tomographic images; (b) image noise reduction; (c) binarization of the lesion area, (d) application of morphological operations to further decrease the level of artefacts; (e) application of a region growing technique to segment the lesion; and (f) creation of a final 3D lesion model. The algorithm is semi-automatic as the initial selection of the region of the lesion and the seeds for the region growing are done interactively. A software tool, performing all of the required steps, was developed in MATLAB. The method was tested and evaluated by analysing anonymized sets of DBT patient images diagnosed with lesions. Experienced radiologists evaluated the segmentation of the tumours in the slices and the obtained 3D lesion shapes. They concluded for a quite satisfactory delineation of the lesions. In addition, for three DBT cases, a delineation of the tumours was performed independently by the radiologists. In all cases the abnormality volumes segmented by the proposed algorithm were smaller than those outlined by the experts. The calculated Dice similarity coefficients for algorithm-radiologist and radiologist-radiologist showed similar values. Another selected tumour case was introduced into a computational breast model to recursively assess the algorithm. The relative volume difference between the ground-truth tumour volume and the one obtained by applying the algorithm on the synthetic volume from the virtual DBT study is 5% which demonstrates the satisfactory performance of the proposed segmentation algorithm. The software tool we developed was used to create models of different breast abnormalities, which were then stored in a database for use by researchers working in this field. ispartof: PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS vol:57 pages:80-87 ispartof: location:Italy status: published

The current contribution presents an approach for creation of complex computational breast phantoms, with included breast abnormalities. In-house developed and validated software tool, called BreastSimulator, is used to create different models of healthy breasts, by varying parameters like shape, size, duct tree features, Cooper ligaments, skin, etc. Separately, different 3D tumour models are constructed from segmented tumour regions on sets of real tomosynthesis images from real patients. A semi-automatic algorithm was developed to segment the abnormalities in the images. The algorithm applies a series of image processing operations and region-growing techniques with minimal interaction from the user to find the areas of the lesions. The flat tumour images are then correctly stacked and stored in a 3D voxel matrix, matching the desired resolution. Relevant information about the lesion (voxel size, matrix size, geometrical centre, etc.) is also saved. Selected tumour models are then inserted at various locations into the computational models of the healthy breasts. Examples of simulated mammographic and tomosynthesis images from such breast phantoms are presented to illustrate the potential of the proposed approach. Combining mathematical breast modelling with segmented real 3D tumour shapes results in the creation of realistic breast phantoms. The approach allows implementation of multiple scenarios and unlimited number of cases, which can be used for further software modelling and investigation of breast imaging techniques.

Purpose – The purpose of this paper is to develop a realistic computational model of carbon fibre reinforced polymer (CFRP) structures dedicated for in-silico investigations of the use of X-ray-based imaging techniques as non-destructive testing (NDT) of CFRP parts. Design/methodology/approach – CFRPs contain layers of carbon-fibres bundles within resin. Bundles’ orientation in the different layers is arranged with respect to each other at a well-defined primary direction. In the model, the bundle was simulated as a circular cylinder. The resulted model is a stack of layers of unidirectional bundles having orientation of 0°/90°/45°/−45°. Two CFRP structures were modelled: a flat CFRP part and a real shaped CFRP clip. A porous layer and non-carbon fibres were inserted within each model, respectively. X-ray projection images were generated with a dedicated simulation programme. Three setups were investigated: radiography, tomosynthesis and cone-beam CT (CBCT). Findings – Results showed that porosity and non-carbon fibres were visible with all X-ray-based techniques. Tomosynthesis and CBCT, however, provide higher quality image of defects. Practical implications – The CFRP computational model is a valuable tool in design, testing and optimization phase of X-ray-based imaging techniques for use in NDT of composite materials. Simulated images are generated within a short time; thus results from virtual optimization and testing are obtained very fast and at low cost. Originality/value – An innovative computational model of CFRP structures, dedicated for X-ray imaging simulations, has been developed. The model is characterized by simplicity in its creation and realistic visual appearance of the produced X-ray images.

Preoperative assessment of the liver volume and function of the remnant liver is a mandatory prerequisite before performing major hepatectomy. The aim of this work is to develop and test a software application for evaluation of the residual function of the liver prior to the intervention of the surgeons. For this purpose, a complete software platform consisting of three basic modules: liver volume segmentation, visualization, and virtual cutting, was developed and tested. Liver volume segmentation is based on a patient examination with non-contrast abdominal Computed Tomography (CT). The basis of the segmentation is a multiple seeded region growing algorithm adapted for use with CT images without contrast-enhancement. Virtual tumor resection is performed interactively by outlining the liver region on the CT images. The software application then processes the results to produce a three-dimensional (3D) image of the “resected” region. Finally, 3D rendering module provides possibility for easy and fast interpretation of the segmentation results. The visual outputs are accompanied with quantitative measures that further provide estimation of the residual liver function and based on them the surgeons could make a better decision. The developed system was tested and verified with twenty abdominal CT patient sets consisting of different numbers of tomographic images. Volumes, obtained by manual tracing of two surgeon experts, showed a mean relative difference of 4.5%. The application was used in a study that demonstrates the need and the added value of such a tool in practice and in education.

Overlay alignment is a concern for nanolithography applications, in particular, for those using step and repeat techniques targeting next-generation lithographic applications. In this context, a new method and a proof of concept (POC) setup for accurately aligning a mask with a semiconductor wafer is presented. Utilizing active scanning probe technology, the method is employable for various lithographic techniques such as photolithography, electron- and ion-beam lithography, nanoimprint lithography (NIL). The developed method is demonstrated in the example of NIL. It employs compact highly integrated atomic force microscopes (mini-AFM), which are fixed on the lithographic template. The mini-AFM systems are applied for imaging of the surface relief marks on the semiconductor wafer to carry out the alignment process. In a next step, the obtained AFM section images are used to calculate the deviations and steer the bottom stage carrying the processed wafer in order to achieve the desired positioning accuracy. A POC test setup was built for emulation of the alignment procedure. Several measurement studies are addressed to evaluate the applicability of the overlay alignment method. As a result, it is shown that the implemented test setup is able to determine the positioning error of the bottom stage carrying the wafer with an accuracy of around 10 nm (without temperature compensation).

A common approach in the development and improvement of diagnostic imaging techniques is the use of anthropomorphic phantoms. These phantoms can be physical or computational. In this study the creation of computational breast phantoms with included pathological formations is presented. The creation of the realistic phantoms is achieved by utilizing real patient data in the form of tomographic images. The 3D tumour models are generated by segmenting the regions containing tumour formations in the patient images. The segmentation is performed with a developed software tool based on a semi-automatic algorithm, which makes use of a series of image processing and region growing techniques. The software tool also provides the user an opportunity for corrections after the automated segmentation. Then the acquired flat images are stacked in a 3D voxel matrix. Creation of the computational healthy breast model as well as the compression procedure is achieved with a software tool called BreastSimulator. The healthy breast model and the segmented tumour formation are then interactively combined with a software tool called XRAYImagingSimulator. While the user can select a location for the tumour formation, also an automatic software processing is applied for integration between the two computational models. The simulation procedure for acquiring tomographic images from the created realistic breast phantom with included tumour formation is performed with the XRAYImagingSimulator software tool. Finally, the acquired simulation images are reconstructed with a software tool called FDKR. The combination of mathematical models of the breast and tumour models segmented from real patient data leads to the creation of realistic breast phantoms, which can be used in X-ray imaging simulation studies. The presented approach gives an opportunity for generation of multiple cases of breast cancer; thus allowing for further progress in already existing software models and techniques in diagnostic imaging. Acknowledgements This research is supported by the Bulgarian National Science Fund under grant agreement DN17/2. This project also has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 692097.

Physical phantoms are a basic tool for the assessment and verification of performance standards in daily clinical practice of X-ray imaging modalities. Most of the physical phantoms have a homogeneous background with inserted test objects. For research purposes, many of the existing phantoms should be developed to a next degree of sophistication in order to mimic the real objects more closely in terms of radiographic and anatomical properties. The development of 3D printing technologies opens potentially new possibilities for phantom manufacturing. The aim of this study is to explore the absorption properties of common 3D printing materials such as resins, PLA, ABS, etc. and to estimate their potential for production of the anthropomorphic phantoms. To achieve this goal, step-wedge phantoms were computationally modeled and then manufactured using two popular 3D printing technologies: stereolithographic and fused-deposition modeling. X-ray images of the phantoms were acquired, using monochromatic beam at ID17, ESRF, Grenoble for three energies – 30 keV, 45 keV and 60 keV. Experimental data were further processed to obtain the linear attenuation coefficients of these materials. Comparison with theoretical data for the linear attenuation coefficients for breast tissues was performed. Based on the results, several breast anthropomorphic phantoms were manufactured. Finally, a practical approach for printing anthropomorphic phantoms has been established and verified. From the studied materials, most of the resins, Hybrid, PET-G show absorption properties close to the glandular tissue, while ABS shows absorption characteristics close to these of the adipose tissue. It allows the production of complex shapes, which are very advantageous for the case of breast phantoms. Acknowledgements This research is supported by the Bulgarian National Science Fund under grant agreement DN17/2. This project also has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 692097.

Aim of this study is to present a software tool designed to extract texture parameters from x-ray images. The tool is developed in the MATLAB environment and is dedicated to facilitate the research in x-ray imaging. A program called BreastSimulator is used to generate an anthropomorphic software model of an averaged in size breast. Further on, the computer model undergoes simulated mechanical compression to mimic the conditions during mammographic acquisition, and subsequently exported as STL file used for 3D printing. The physical model is printed with a stereolithographic 3D printer with resolution of 100 µm from Clear Resin. The model is then filled with animal fat and irradiated at GE Senographe digital mammography unit. On the other side, the software model is “irradiated” by a specialized program. The resulting x-ray images from both the simulated and the physical models are compared by their parameters, extracted with the help of the created software tool.

Introduction Digital Mammography is a fundamental technique in breast cancer diagnosis. DM returns a two-dimensional representation of a three-dimensional object. Therefore, tissues belonging to different planes are all projected on the same X-ray image plane. Digital Breast Tomosynthesis (DBT) and Breast Computed Tomography (BCT) are two forms of 3D X-ray breast imaging for diagnostic exam developed to overcome this limitation. Recently, it has been shown that for the generation of the radiographic contrast it is possible to exploit also the information related to the wave phase shift introduced in the propagation of X-rays in matter. Purpose To compare image quality in monochromatic DBT and BCT scans with propagation based phase contrast imaging of a 3D breast phantom. Materials and methods The CIRS Model 020 BR3D is used to evaluate the image quality in the two modalities. The standard package consists of 6 slabs of thickness of 1 cm, each slice is produced by tissue equivalent materials in an approximate 50/50 ratio by weight. The central slab of the stack contains assortments of simulated microcalcifications, fibers and masses. The experiment was conducted on the biomedical beamline ID 17 at the European Synchrotron Radiation Facility. The comparison will be made in terms of noise, contrast, CNR, SNR and spatial resolution, for simulated masses and microcalcifications. Results First measurements show slightly higher values for CNR and C for masses in CT images than in DBT images. Conclusion The image quality in DBT and BCT monochromatic images of a 3D breast phantom was evaluated.

The paper presents an approach to be used in the face-to-face and the on-line phases of one of the chapters in module from the EUTEMPE-RX project. The module and the project are aimed at the training of medical physics experts in radiology. The approach consists of: (a) generation of computational anthropomorphic phantoms, (b) program scripts, specifically developed to convert computational phantoms to suitable formats used with 3D printing devices, and (c) 3D printing of software models. In this paper, the design and printing of a 3D breast glandular system has been demonstrated. Two small size breast phantoms differing in the complexity of their duct tree system were generated with a dedicated program. A set of image processing techniques were applied on the obtained breast phantoms to obtain an STereoLithography (STL) file format of the breast’s duct tree that was imported within the software of the 3D printer used to print the sample breast tree.

The major objective is to adopt, apply and test developed in-house algorithms for volumetric breast reconstructions from projection images, obtained in in-line phase-contrast mode. Four angular sets, each consisting of 17 projection images obtained from four physical phantoms, were acquired at beamline ID17, European Synchroton Radiation Facility, Grenoble, France. The tomosynthesis arc was ±32°. The physical phantoms differed in complexity of texture and introduced features of interest. Three of the used phantoms were in-house developed, and made of epoxy resin, polymethyl-methacrylate and paraffin wax, while the fourth phantom was the CIRS BR3D. The projection images had a pixel size of 47 μm × 47 μm. Tomosynthesis images were reconstructed with standard shift-and-add (SAA) and filtered backprojection (FBP) algorithms. It was found that the edge enhancement observed in planar x-ray images is preserved in tomosynthesis images from both phantoms with homogeneous and highly heterogeneous backgrounds. In case of BR3D, it was found that features not visible in the planar case were well outlined in the tomosynthesis slices. In addition, the edge enhancement index calculated for features of interest was found to be much higher in tomosynthesis images reconstructed with FBP than in planar images and tomosynthesis images reconstructed with SAA. The comparison between images reconstructed by the two reconstruction algorithms shows an advantage for the FBP method in terms of better edge enhancement. Phase-contrast breast tomosynthesis realized in in-line mode benefits the detection of suspicious areas in mammography images by adding the edge enhancement effect to the reconstructed slices.

Digital tomosynthesis is a method of limited angle reconstruction of tomographic images produced at variable heights, on the basis of a set of angular projections taken in an arc around human anatomy. Reconstructed tomograms from unprocessed original projection images, however, are invariably affected by tomographic noise such as blurred images of objects lying outside the plane of interest and superimposed on the focused image of the fulcrum plane. The present work investigates the performance of two approaches for generation of tomograms with a reduced noise: a generalised post-processing method, based on constructing a noise mask from all planes in the reconstructed volume, and its subsequent subtraction from the in-focus plane and a filtered Multiple Projection Algorithm. The comparison between the two algorithms shows that the first method provides reconstructions with very good quality in case of high contrast features, especially for those embedded into a heterogeneous background.

Purpose We present the development and the current state of the MaXIMA Breast Tumours Models’ Database, which is intended to provide researchers with both segmented and mathematically modelled realistic in shape computer-based breast tumours. Methods The database contains various 3D images of breast cancers of irregular shapes, collected from routine patient examinations or dedicated scientific experiments. It also contains images of simulated tumour models. To extract the 3D shapes of the breast cancers from patient images, an in–house developed and well evaluated segmentation algorithm was applied on 60 tomosynthesis sets from patients diagnosed with malignant and benign lesions. In addition, three breast mastectomy cases scanned at a CT system were added. This algorithm includes a series of image processing operations and region-growing techniques with minimal interaction from the user to find and segment the areas of the lesions. Modelled computational breast tumours are generated following different approaches and also stored in the database. Each record in the database is supported with relevant information, e.g. voxel size and resolution, matrix size, geometrical centre, etc. Results The MaXIMA Imaging Database currently contains 68 unique breast cancer models obtained by segmentation of 3D patient breast tomosynthesis images; 8 models obtained by segmentation of 3D micro CT images of biopsy specimens; and 20 models based on mathematical algorithm. An application of the tumour models is to insert them into computationally generated healthy breast phantom generated with dedicated software tools (e.g. the BreastSimulator tool). The resulted combined computational breast models are used to study the visibility of breast tumours in 3D breast imaging techniques. This approach allows implementation of multiple scenarios and unlimited number of cases, which can be used for further software modelling and investigation of breast imaging techniques. The database interface is web-based, i.e. is platform independent, user friendly and is indented to be made freely accessible through internet after the completion of the MaXIMA project. Conclusions The developed database serves as an imaging data source for researchers, working on breast imaging and early breast cancer detection with the help of existing or newly developed imaging modalities.

Purpose This paper presents a complete and validated computer-based system dedicated to X-ray phase contrast breast imaging research. The system comprises three main modules: (a) a module for generation of computational breast models, (b) a module for generation of phase-contrast X-ray images from computational phantoms in 2D and 3D acquisition setup, and (c) a module for image reconstruction. Methods The module for computational breast models is based on the BreastSimulator tool, used to generate breast models of various sizes and to compress them to a desired thickness. The module for the generation of phase-contrast images is used to model the image acquisition geometry and formation of X-ray images. The image reconstruction is done with a software tool, based on an in–house built reconstruction techniques class library, which is a dedicated object-oriented library for X-ray based applications. The capability of this system to correctly calculate phase-contrast tomographic images was tested by comparing simulated versus experimental images obtained from anthropomorphic breast phantoms. Three anthropomorphic computational breast phantoms were designed from white and grey resin by using the available stereolithography 3D printer. Experimental projection images were acquired and simulated images were generated, considering a breast tomosynthesis setup. Experiments were conducted at beamline ID17, ESRF. Simulations replicated the experimental setup. Images in a tomosynthesis mode were generated and tomograms were calculated by using the reconstruction module. Results Results show very good visual agreement between simulated and experimentally obtained tomosynthesis images. In addition, selected tomosynthesis images from the physical and computational breast phantoms were quantitatively evaluated for set of imaging parameters such as skewness, kurtosis, the power-law exponent, β , of the power spectrum and fractal dimension. Analysis and the comparison of these parameters between simulated and experimental images also show a very good coincidence. Conclusions The platform is currently used in the process of development of a dedicated breast phantom for phase contrast imaging techniques. The system will be a valuable tool in studying new X-ray imaging techniques based on phase contrast, such as phase contrast tomosynthesis and CT.

Breast physical phantoms are a basic tool for the assessment and verification of performance standards in daily clinical practice of x-ray breast imaging modalities. They are also invaluable in testing and evaluation of new x-ray breast modalities to be potentially established, e.g. breast computed tomography, dual-energy breast CT and phase-contrast mammography and tomography. Nowadays, there is a lack or there are only a limited number of breast physical phantoms available for this purpose. The aim of this study is to explore a range of 3D printing materials such as resins, PLA, ABS, Nylon etc, to determine their attenuation and refractive properties, and to finally compare them to the properties of the breast tissues: adipose, glandular and skin. To achieve this goal, step-wedge phantoms were computationally modeled and then manufactured using stereolithographic and fused-deposition modeling technologies. X-ray images of the phantoms were acquired, using monochromatic beam at ID17, ESRF, Grenoble for three energies-30 keV, 45 keV and 60 keV. Experimental data were further processed to obtain the linear attenuation coefficients of these materials. Comparison with theoretical data for the linear attenuation coefficients and the refractive indexes for breast tissues was performed. From the studied materials, most of the resins, Nylon, Hybrid, PET-G show absorption properties close to the glandular tissue, while ABS shows absorption characteristics close to these of the adipose tissue. For phase-contrast imaging, it turns out that the ABS combined with resin-based materials to represent the adipose and glandular tissues, respectively may be a good combination for manufacturing of a phantom suitable for these studies. These results can be used for the design and the construction of a new physical anthropomorphic phantom of the breast with improved anatomical and radiological characteristics dedicated for advanced mammography imaging techniques implemented at higher photon energies. ispartof: PHYSICS IN MEDICINE AND BIOLOGY vol:63 issue:17 ispartof: location:England status: published

Image reconstruction from X-ray cone-beam projections collected along a single-circular source trajectory is commonly done using the Feldkamp (FDK) algorithm which performs well only with a small cone-angle. Although this method does not provide an “exact” reconstruction, the approximation is considered adequate for many purposes. In FDK reconstruction the degree of inaccuracy is highly object-dependent, and the largest errors are to be expected for planes parallel to and remote from the midplane. In this study we investigated the possibility to accurately reconstruct these regions by applying FDK algorithm along three-orthogonal to each other circular scanning trajectories. After appropriate weighting, based on the expected errors for each individual reconstruction, the final 3D volume contains the most precisely recovered values. By comparing the quality of 3D reconstructed images using FDK algorithm on projections acquired along classical single-circular and two- and three-orthogonal circular trajectories, we show that using three-orthogonal circular isocentric orbits with an error-based weighted averaging, image quality of reconstructed slices significantly improves, reconstruction error due to circular scanning is reduced and becomes almost independent of the slice position even for relatively large cone-angles.

This paper discusses approaches for presenting complex educational material for education and training in Medical Physics and Biomedical Engineering through electronic and online tools. Issues and solutions throughout the development of the electronic presentation for the materials are demonstrated and explained. An example with a dedicated educational application is given. The application is a cross-platform online tool that can be implemented in both conventional computers and hand held devices. Materials in the paper are developed within the framework of the EUTEMPE RX project related to the qualification of the Medical Physics Experts in Diagnostic and Interventional Radiology.

Biomedical Engineering (BME) is a modern and dynamic specialty that is predicted to grow over the next decades, partly due to increasing penetration of technological processes and devices into the healthcare system and medical practice, education and research. BME education is regarded as an important tool to support development of healthcare systems and medical industry. BME education in Armenia has been present at certain higher education institutions (HEIs) for some period of time, however the existing study programs need to be updated according to modern standards and practices, and the capacity of the institutions delivering the program needs to be expanded. The 3-year curriculum development project ”Biomedical Engineering Education Tempus Initiative in Eastern Neighboring Area” (BME-ENA) financed through the EU’s Tempus IV funding instrument, involves 17 institutions from 11 EU and ENA countries and is aimed primarily at development and implementation of an innovative joint MSc program in BME amongst the participating universities. Armenia is represented by two leading HEIs – the State Engineering University of Armenia (SEUA), and the Russian-Armenian (Slavonic) University (RAU), and an NGO working in the field of medical technologies – Armenian Association of Telemedicine (AATM). The project team from Armenia has by now held several working meetings locally and with the international partners, which have resulted in development of the new curriculum outline for the joint BME program, incorporating approaches and recommendations of the European project partners. The BME-ENA project is expected to provide an important platform for modernizing BME education in Armenia and bringing it in accordance with current European standards.

Computed tomography (CT) reconstruction methods assume imaging of static objects; object movement during projection data acquisition causes tomogram artifacts. The continuously moving heart, therefore, represents a complicated imaging case. The associated problems due to the heart beating can be overcome either by using very short projection acquisition times, during which the heart may be considered static, or by ECG-gated acquisition. In the latter case, however, the acquisition of a large number of projections may not be completed in a single breath hold, thus heart displacement occurs as an additional problem. This problem has been addressed by applying heart motion models in various respiratory motion compensation algorithms. Our paper focuses on cone beam computed tomography (CBCT), performed in conjunction with isocentric, fluoroscopic equipment, and continuous ECG and respiratory monitoring. Such equipment is used primarily for in-theater three-dimensional (3-D) imaging and benefits particularly from the recent developments in flat panel detector technologies. The objectives of this paper are: (i) to develop a model for the motion of the heart due to respiration during the respiratory cycle; (ii) to apply this model to the tomographic reconstruction algorithm, in order to account for heart movement due to respiration in the reconstruction; and (iii) to initially evaluate this method by means of simulation studies. Based on simulation studies, we were able to demonstrate that heart displacement due to respiration can be estimated from the same projection data, required for a CBCT reconstruction. Our paper includes semiautomatic segmentation of the heart on the X-ray projections and reconstruction of a convex 3-D-heart object that performs the same motion as the heart during respiration, and use of this information into the CBCT reconstruction algorithm. The results reveal significant image quality improvements in cardiac image reconstruction.

The image intensifier (II)-based imaging systems, as radiotherapy simulators or C-arm X-ray units, have also been used for image acquisition in computed tomography. When analogue-to-digital conversion is performed on the output signal of the television camera, the accuracy for low-amplitude video signals, corresponding to X-ray pathways crossing high attenuation structures, is limited. To deal with this lack of accuracy, we investigated the benefits of using a logarithmic amplifier (LOGAMP) inserted between the television camera output and the analogue-to-digital converter (ADC) in the image acquisition chain. Such a device was intended to provide better use of the available ADCs of a given resolution and actually to reduce the quantization noise. Simulated data were used in this study, and cases with and without logarithmic amplifier were compared. Based on the simulation results, we formulate requirements for several signal and acquisition system parameters where the use of such a circuit is recommended.

Major hepatectomy causes a risk of postoperative liver dysfunction, failure, and infections like surgical site infection. Preoperative assessment of the liver volume and function of the remnant liver is a mandatory prerequisite before performing such surgery. The aim of this work is to develop and test a software application for evaluation of the residual function of the liver prior to the intervention of the surgeons. For this purpose, a technique for evaluation of liver volume from computed tomography (CT) images has been developed. Furthermore, the methodology algorithms were implemented and incorporated within a software tool with three basic functionalities: volume determination based on segmentation of liver from CT images, virtual tumour resection and estimation of the residual liver function and 3D visualisation. Forty-one sets of abdominal CT images consisting of different number of tomographic slice images were used to test and evaluate the proposed approach. Volumes that were obtained after manual tracing by two surgeon experts showed a relative difference of 3.5 %. The suggested methodology was encapsulated within an application with user-friendly interface that allows surgeons interactively to perform virtual tumour resection, to evaluate the relative residual liver and render the final result. Thereby, it is a tool in the surgeons’ hands that significantly facilitates their duties, saves time, and allows them to objectively evaluate the situation and take the right decisions. At the same time, the tool appears to be appropriate educational instrument for virtual training of young surgeon specialists.

Emerging X-ray breast imaging applications require the use of realistic physical three-dimensional phantoms are breast CT, phase-contrast mammography and the existing breast Tomosynthesis, dedicated to screen as early as possible and diagnose cancer in breast. However, manufacturing of such phantoms meets difficulties related to the current technology, suitable materials, manufacturing precision, format of the software models. This paper reports the preliminary results from simulation studies aiming to investigate mixtures prepared from epoxy resin and iodine powder in specific ratios as tissue substitutes for X-ray breast imaging. For each material, mass and linear attenuation coefficients were calculated for the X-ray energy range from 10 to 32 keV. Mixtures of epoxy resin and up to 1.8% iodine powder turn to be a suitable option for tissue substitutes. Selected materials were used in simulations of breast lesions with blurry edges.

Introduction Anthropomorphic phantoms play a critical role in the contemporary development of Diagnostic Radiology. The Anthropomorphic Phantom educational module has been successfully developed to provide education and training of Medical Physics Experts in the field of Radiology. Purpose The aims were to familiarize the participants with the role of the physical and virtual anthropomorphic phantoms and the possibility of performing virtual clinical trials using existing and new Diagnostic and Interventional Radiology technologies. Method The Anthropomorphic Phantoms module is one of the 12 modules of the EUTEMPE-RX course. Teaching methodology includes e-learning and face-to-face approaches. The course is organized in a blended format that includes lectures, computer-based exercises, visits to hospital for experimental work and discussion sessions. The online part was developed on SEKOIA platform and included 10 chapters with state of the art reviews in the field, introduction to software used for X-ray imaging and examples. Results The face-to-face part started on September 7, 2015 at the Technical University of Varna, and lasted one week. Lectures and practical work were delivered to seventeen participants from 14 European countries. All lectures were led by worldwide recognized researchers in the field of anthropomorphic phantoms and their use in the research and clinical practice. The focus was on the practical work and the development of a work project. All participants passed successfully the exam. Conclusions The main aims of the module were successfully obtained. Selected project works are currently under detail development and will be submitted for publication.

The work is dedicated to the discovering and estimation of local deformations on smooth surfaces of unknown shape. Stereo vision principle is used. The analyzed surface is illuminated by a structured light from a laser projector and an image of the surface is acquired by a photo camera. A 3D approximated object surface is computed and used to determine the corrections of the camera image perspective distortions. Another light pattern of stripes is next projected over the object and the local deformations of its surface are estimated by calculating the Euclidian distances between the contours of the stripes and their low-order polynomial approximations on the acquired image. The experimental results confirm the feasibility of the proposed approach.

Objective: It is well established that computer based models of x-ray imaging systems are basic and very important tools for developing and evaluating new emerging x-ray imaging techniques, optimizing technical parameters, and performing feasibility studies prior to implementation in clinical practice. Such models are essential for the development and the establishment of new breast x-ray imaging modalities that aim to detect and better characterize breast lesions in their early stage. This work presents a complete software package, called BreastSimulator, dedicated for breast x-ray imaging research. Methods: The package consists of four modules used to create three-dimensional breast models in compressed and uncompressed state, simulate x-ray mammographic images and visualize the results of the simulations. The module that is used to generate breast models, Breast Modeling Module, consists of several sub-modules that are utilized to model the different breast components: external shape, glandular and adipose tissue, breast lesion, skin, pectoralis and lymphatics. The Compression Module is dedicated to simulate the mechanical compression of the breasts. Mammographic projection images are obtained with simulation of x-ray photon transport starting from the x-ray source, passing through the breast model and reaching the detector. This is accomplished in the Image Generation Module. Finally, the results of the simulations, i.e. breast models and mammographic images can be seen with the Visualization Module. Results: Here, we demonstrate the application of the software package in conventional and dual-energy mammography as well as compression studies, as examples to highlight basic functions and applications of Breast Simulator. The first study aimed to define the optimal pair of ‘low’ and ‘high’ monochromatic x-ray energies for dual-energy mammography. It involved the synthesis of 225 dual-energy images obtained from combinations of ‘low’ and ‘high’ energy images acquired in the energy range 14 to 28 keV. Images were generated from a medium sized dense breast model that contained one calcification. The study showed that 17/28 keV incident monoenergetic beams are optimal to obtain maximal calcification detectability for this breast. The second study demonstrated the effect of breast compression on the quality of the obtained mammograms. It included a breast model based on breast CT slices subjected to simulated compression and generation of mammographic images. Increased image quality is observed for mammograms obtained from breasts with reduced thickness. The characteristics of the x-ray beams that exit a small dense breast model were investigated in the third study. For two mammographic spectra used in mammography imaging, the mean energy of the transmitted x-rays and the mean exit angle of the scattered radiation increase as the incident x-ray energy increases. Conclusions: We believe that this tool and its functionalities will speed up the development, testing and optimization of new breast imaging modalities such as breast tomosynthesis, cone-beam CT and advanced two-dimensional techniques like dual-energy as well as specific parts of imaging chain, such as x-ray source, detector and acquisition geometry.

Closed intramedullary nailing is a common technique for treatment of femur and tibia fractures. The most challenging step in this procedure is the precise placement of the lateral screws that stabilize the fragmented bone. The present work concerns the development and the evaluation of a method to accurately identify in the 3D space the axes of the nail hole canals. A limited number of projection images are acquired around the leg with the help of a C-arm. On two of them, the locking hole entries are interactively selected and a rough localization of the hole axes is performed. Perpendicularly to one of them, cone-beam computed tomography (CBCT) reconstructions are produced. The accurate identification and localization of the hole axes are done by an identification of the centers of the nail holes on the tomograms and a further 3D linear regression through principal component analysis (PCA). Various feature-based approaches (RANSAC, least-square fitting, Hough transform) have been compared for best matching the contours and the centers of the holes on the tomograms. The robustness of the suggested method was investigated using simulations. Programming is done in Matlab™ and C ++. Results obtained on synthetic data confirm very good localization accuracy – mean translational error of 0.14 mm (std = 0.08 mm) and mean angular error of 0.84° (std = 0.35°) at no radiation excess. Successful localization can be further used to guide a surgeon or a robot for correct drilling the bone along the nail openings.

Closed intramedullary nailing is the common technique for treatment of femur and tibia fractures. The most challenging step in this procedure is the precise placement of the lateral screws that stabilize the fragmented bone.

The hole code is commonly used to represent unique document numbers - in passports, health insurance cards, etc. The characteristics of the code make it quite appropriate for implementation of an automatic reading. Such implementation would help for a faster and more reliable personal data input in the relevant administration offices.

Telemedicine is being rapidly developed. In isolated places, i.e. islands, mountains or ships, where access to medical services is time-consuming or infeasible, it can prove life-saving. Powerful programming languages such as C++ and Java™ are supported by the modern mobile phones, which gives a possibility for easy developing of useful telemedicine applications. In this paper we present an approach for distant simultaneous monitoring of several ECG signals. The individual channel signals are packed through modulation into a complex sound signal, which is further recorded by a mobile phone. The phone is interfaced to the measuring device through a modified hands-free accessory. JAVA applications allow storing the signals in multimedia files and their transmitting to a second mobile phone via MMS or other means. A real-time ECG monitoring is also possible. The feasibility of the signal processing algorithms is confirmed through simulations in MATLAB.

Any organ motion during the projection acquisition causes blurring artefacts in the computed tomography (CT) reconstructions. It is a drawback in applications of cone beam CT (CBCT) for which, the complete scanning cannot be performed during a single breath hold. Our study proposes a new approach for estimation of the organ's respiratory displacement, from the same projection data, required for the CBCT with sampling over a circular trajectory. The processing includes semiautomatic outlining of the organ's boundaries on the X-ray projections, creating approximate shadow images, and constructing, from them, of a convex 3D organ-like structure, with the property to perform the same respiratory displacement as the one of the organ of interest. The motion is derived as a function of the respiration and can be used for respiratory motion correction in the following CBCT algorithm. Simulation results reveal significant improvements of the image quality in a cardiac tomogram reconstruction.

PurposeTo present and validate a computer-based simulation platform dedicated for phase contrast x-ray breast imaging research. MethodsThe software platform, developed at the Technical University of Varna on the basis of a previously validated x-ray imaging software simulator, comprises modules for object creation and for x-ray image formation. These modules were updated to take into account the refractive index for phase contrast imaging as well as implementation of the Fresnel-Kirchhoff diffraction theory of the propagating x-ray waves. Projection images are generated in an in-line acquisition geometry. To test and validate the platform, several phantoms differing in their complexity were constructed and imaged at 25keV and 60keV at the beamline ID17 of the European Synchrotron Radiation Facility. The software platform was used to design computational phantoms that mimic those used in the experimental study and to generate x-ray images in absorption and phase contrast modes. ResultsThe visual and quantitative results of the validation process showed an overall good correlation between simulated and experimental images and show the potential of this platform for research in phase contrast x-ray imaging of the breast. The application of the platform is demonstrated in a feasibility study for phase contrast images of complex inhomogeneous and anthropomorphic breast phantoms, compared to x-ray images generated in absorption mode. ConclusionsThe improved visibility of mammographic structures suggests further investigation and optimisation of phase contrast x-ray breast imaging, especially when abnormalities are present. The software platform can be exploited also for educational purposes. A simulation platform dedicated for PhC x-ray breast imaging research is developed.Various in complexity phantoms for PhC (from simple cuboids to anthropomorphic breasts) are modelled.Generation of PhC images from thick objects (breast models) is now feasible.Simulation results are validated against measurements performed at ESRF.Experimental studies on PhC may be optimized in advance.

This paper presents a computer-based system dedicated to x-ray phase contrast (PhC) imaging research. It consists of two main modules: (a) a module for generation of x-ray PhC images from computational phantoms and (b) a module for image reconstruction. The module for generation of x-ray images consists of submodules dedicated to modelling of computational phantoms, modelling the image acquisition geometry and formation of x-ray images. The module for image reconstruction is a software tool, based on an in-house built reconstruction techniques class library, which is a dedicated object-oriented library for x-ray based applications. The computer-based system is tested for its feasibility to generate correctly PhC projection images and to reconstruct from them, considering a breast tomosynthesis setup. Two computational phantoms were designed for the simulations: a 4 cm thick polymethyl methacrylate phantom with air channels and a 2 cm thick rectangular polystyrene flask filled with epoxy resin mixture. Images in a tomosynthesis mode were generated and tomograms were calculated by using the reconstruction module. Simulations were validated with the help of experimental study conducted at beamline ID17, ESRF. Results show good visual agreement between simulated and experimentally obtained images. The platform, after its complete evaluation, may be useful in studying new x-ray imaging techniques based on phase contrast. Applications are foreseen also in education and training.

Primary goal of this study is to investigate the visibility of low contrast details of different size on images obtained at conventional mammography unit, and at a monochromatic synchrotron radiation source, in absorption based and phase contrast imaging setups. For this purpose, three physical phantoms made of paraffin as a bulk material were used. They embedded various low contrast features. Single projection images were acquired with the GE Senographe mammography unit and at the beamline ID17, ESRF, Grenoble. Comparison of images showed that images obtained in a phase contrast mode have more visible details than the images acquired either in absorption mode at the synchrotron or at the conventional x-ray mammography unit. Analysis for δ and μ suggests that paraffin may be a suitable material for the manufacturing of tissue-mimicking phantoms dedicated to phase contrast applications. Results will be exploited in the development of a dedicated phantom for phase contrast imaging.