Dual‐energy mammographic imaging experimental tests have been performed using a compact dichromatic imaging system based on a conventional x‐ray tube, a mosaic crystal, and a 384‐strip silicon detector equipped with full‐custom electronics with single photon counting capability. For simulating mammal tissue, a three‐component phantom, made of Plexiglass, polyethylene, and water, has been used. Images have been collected with three different pairs of x‐ray energies: , , and . A Monte Carlo simulation of the experiment has also been carried out using the MCNP‐4C transport code. The Alvarez‐Macovski algorithm has been applied both to experimental and simulated data to remove the contrast between two of the phantom materials so as to enhance the visibility of the third one.

This work proposes a compact dichromatic imaging system for the application of the K-edge digital subtraction technique based on a conventional x-ray tube and a monochromator system.A quasi-monochromatic x-ray beam at the energy of iodine K-edge is produced by Bragg diffraction on a mosaic crystal.Two thin adjacent beams with energies that bracket the K-edge discontinuity are obtained from the diffracted beam by means of a proper collimation system.They are then detected using an array of Si detectors.A home-made phantom is used to study the image quality as a function of iodine concentration.Signal and signal-to-noise ratio analysis has also been performed.The results are compared with theoretical expectations.

Preliminary results of a dual energy angiography simulation using the Monte Carlo package GEANT 3.2113 [1] are presented and compared to Monte Carlo MCNP-4C [2] results reported before [3]. The simulation is based on an experimental set up consisting of a Plexiglas-aluminium step wedge phantom with 4 cylindrical cavities filled with iodated contrast medium. The silicon 384 microstrip detector was set into edge-on configuration (incoming X-rays parallel to longitudinal axis of the strips) and the properties of the simulated detector just resemble the ones of the real detector. Monochromatic photon beams of 31.5keV and 35.5keV are used to take advantage of the discontinuous variation of the iodine photon absorption at the energy of the K-shell, the key to dual energy subtraction imaging.

We present results obtained with a single photon counting system consisting of 384 silicon microstrips of 100 micron, pitch equipped with 6 RX64 ASICs. The ASIC includes a charge preamplifier, a shaper, a discriminator and a 20-bit counter for each of its 64 channels. The energy resolution of the system has been measured in the range from 9 keV to 32 keV using fluorescence Xray lines from several targets using either an Am-241 source or an X-ray tube. Then, the efficiency of the system has been determined using the specially developed quasi-monochromatic X-ray beams in the energy range 18-36 KeV. Good efficiency has been obtained in the edge-on configuration, which is more suitable for the intended applications. The spatial resolution of the system has been verified using a special microfocus X-ray tube equipped with capillaries. Finally, images of angiographic and mammographic test objects have been obtained with dual energy X-ray beams and have then been processed with the dual energy subtraction technique. In particular, the contrast for the angiographic test object has been evaluated for different concentrations of an iodate solution injected into 1 mm and 2 mm diameter vessels. Further developments, including a double threshold version of the ASIC, are also discussed.

We present First results of Monte Carlo simulation by the general purpose MCNP-4C transport code of an experimental facility at Bologna S. Orsola hospital for studying the possible application of a X-Ray detection system based on a silicon strip detector on a dual energy angiography. The quasi-monochromatic X-ray beam with the detector in the edge-on configuration has been used to acquire images of a test object at two different energies (namely 31 and 35 keV) suitable for the K-edge subtraction angiography application. As a test object a Plexiglas step wedge phantom with four cylindrical cavities, having 1 mm diameter was used. The cavities have been drilled and filled, with iodated contrast medium, whose concentration varied from 370 mg/ml to 92 mg/ml. Both the profiles obtained from measurements and the generated images where reproduced by computer simulation on a first approach to use this technique as an evaluation tool for future developments on the experimental setup.