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.
We are developing a dual system for small-animal imaging in multimodality studies, which consists of a highspatial resolution gamma-camera and a scanner for Near-Infra-Red (NIR) light. The gamma-camera is assembled from a position-sensitive photomultiplier and a scintillation-crystal with parallel-hole collimator. On the other hand, the NIR imaging is designed for near-object scanning, and features two operational modes: Transmission and Fluorescence. In the Transmission mode, the NIR light, coming from five different wavelength LEDs, crosses the sample and is subsequently measured by an array sensor. In the Fluorescence mode, the emission from nanoparticles, such as singlewalled carbon nanotubes (SWCNTs) administered in the imaged object, is excited using the laser. The gamma-camera energy and spatial resolutions have been measured. This latter has been assessed by using specially-designed phantoms like capillary tubes or volumes with cavities filled with a radioactive solution. The NIR-scanner spatial resolution has been determined along two perpendicular directions using standards, placed at different distances from the sensor. The results show that both the NIR scanning-system and the gamma-camera feature good imaging-parameters and can be applied to multimodality studies.
INTRODUCTION: Contrast-enhanced spectral mammography (CESM) is a new technique for cancer investigations. The application of this technique to screen the breast would result in contrast improvement of the different breast lesions. This can be effectively ensured by the use of phantoms. Computational phantoms are one of the ways to investigate the characteristics of the received image and thus to evaluate the whole technique. AIM: The aim of this study is to validate and analyse the design of three different computational phantoms for CESM. MATERIALS AND METHODS: An in-house software tool was used to create three computational phantoms, consisting of iodinated inserts for the simulation of the CESM procedure. The inserts in the phantoms, modelled from Omnipaque, have a radius of 8-10 mm and varying height. The three phantoms are made of polymethyl methacrylate (PMMA), with different shape and composition. One of the phantoms is characterised by a heterogeneous background. For each phantom two x-ray radiographs were generated, one at x-ray energy of 20keV and one at 34 keV. The images were processed to obtain a recombined iodine image, which shows the iodine contrast agent and suppresses the surrounding background tissue. RESULTS: Simulated spectral images demonstrated a great improvement of the image quality compared to low-energy images of the phantoms. The simulations with the inhomogeneous model revealed that the heterogeneous background has been successively depressed while improving the visibility of the iodine inserts.CONCLUSION: The heterogeneous breast phantom might be used as a reference tool for information about the needed iodine concentration which needs to be inserted during the procedure to obtain significant enhancement in the suspicious area.
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