Medical Image Reconstruction and Simulation, Diagnostic Tools and Methods

Digital Tomosynthesis

Digital Tomosynthesis (DTS) is referred to as the limited angle technique, which allows the reconstruction of tomographic planes on the basis of images acquired during a tomographic acquisition pass on a predefined angle. Investigations carried out during the past 25 years clearly demonstrated that tomosynthesis can be successfully used with digitized fluoroscopic data to produce three-dimensional information. It can also be applied to Isocentric Rotational (IR) units, such as Radiotherapy Simulators, Angiographic and Mammography units, without necessitating any modifications to the equipment. Current research is focused on optimization of acquisition parameters, reconstruction algorithms and filtering methods, as well as on the application of DTS along with Dual Energy and Phase Contrast techniques.

Image Reconstruction Algorithms

Development of Algorithms and Software tools aiming at easily implementing, testing and evaluating 3D reconstruction techniques (Class Library for Computed Tomography). The fundamental elements in these tools are classes tightened together in a logical hierarchy. Various utilities (like 3D transformations, loading, saving, filtering of images, creation of planar or curved objects of various dimensions) have been incorporated in the software tools as class methods. They allow the user to easily set up any arrangement of these objects in 3D space and to experiment with many different trajectories and configurations. At present, the library’s class methods are mostly dedicated to the approximate analytical reconstruction algorithms, like the well known FDK algorithm and its variations.

X-ray Imaging Simulator

It is a software tool for design and simulation of X-ray imaging techniques. It consists of four components: Image acquisition, Absorber design, Image formation and Visualization. Software phantoms are modeled as a synthesis of geometrical or voxelized primitives. Simulated projection images are calculated using one of the two following approaches. The first one is to simulate the beam transport through an X-ray imaging system based upon the exponential attenuation of incident beams. This approach is quite fast in image generation, but is limited to the simulation of primary radiation effects only. Alternatively, a Monte Carlo simulation code has been developed and is available for simulation of the major X-ray beam interaction modes.

Breast Simulator

This software tool is used to create three-dimensional breast models, simulate X-ray mammographic images and visualize the results of the simulations. Various breast models composed of external shapes, glandular and adipose tissue, breast lesion, skin, pectoralis and lymphatics may be created. 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. The simulated mammograms closely resemble real mammograms. The breast simulator allows investigation of novel X-ray imaging techniques, and optimisation of parameters that influence the quality of the obtained image of the breast.

X-ray Brain Imaging and Simulation

This research aims to the creation of a complete software platform for design and simulation of novel X-ray brain imaging techniques, which consists of 3 main components:

  • The 3D brain phantom based on other available phantoms, modified and improved to enable X-ray imaging simulation. This phantom is improved in terms of resolution and level of modeled details.
  • The X-ray image acquisition simulation tool, able to simulate any required acquisition geometry or method (CT, Limited Arc, Spiral CT) for a variety of X-ray sources and resulting beam profiles (parallel, cone beam, pencil beam) along with all needed types of spectra (monochromatic or polychromatic beams) and any desired detector response. The X-ray matter-interactions simulation is performed using Monte Carlo techniques.
  • Image Processing tools of in-house design, using novel reconstruction techniques, and enabling the simulation of new multi-energy image fusion and image enhancement techniques.

Monte Carlo Radiotherapy Simulation

It is a software tool that simulates radiotherapy applications based on Monte Carlo techniques. It incorporates components for beam generation, irradiation set up, radiation transport modeling, phantom construction, visualization and dose distribution calculation. “Omoiotheta” Beam Modulators for rotational radiotherapy are also simulated. They are diminished copies of the organs at risk that stay parallel to them during gantry rotation, acting as high efficiency protectors.

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