Single Photon Counting X-ray Imaging Research Articles

Testing of thickness homogeneity of Si crystal membranes using GaAs Timepix detector

Silicon (Si) membranes were prepared using high precision advance nanomachining technology utilizing single point diamond turning (SPDT). We showed that SPDT allowed to produce membranes with a surface undulation down to 500 nm over diameter of 7800 μm which corresponds to a high accuracy of the surface profile. We used X-ray digital radiography based on absorption contrast for a non-destructive measurement of the thickness distribution within a thin Si crystal membrane. The semi-insulating Gallium Arsenide (SI GaAs) pixel detector bump-bonded to the Timepix readout chip was used as a highly efficient single photon counting X-ray imaging detector. Comparison of thickness values obtained by the SI GaAs Timepix detector with values obtained with a surface stand-type micrometer gauge showed comparable results and the thickness variation within the membrane was clearly detected with a standard deviation down to 8.4 μm. The thickness resolution down to 5 μm over distances of 4–8 mm was achieved in selected areas of the sample.

Environment for Single Photon Counting X-Ray Imaging System Design

In this paper, we introduce an environment for multi-energy X-ray imaging system design. The environment has an emulator for pixel sensor, followed by data-acquisition and pre-processing unit. The proposed environment provides the way to verify the functionality of the image reconstruction without X-ray pixel sensor, which is under development.

Single Photon Counting X-Ray Imaging System Using a Micro Hole and Strip Plate

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A Xe-based single photon counting x-ray imaging system, based on a Micro-Hole &amp; Strip Plate (MHSP), using a resistive charge division method was implemented. The MHSP is a hybrid microstructure that combines in a single element the features of the Gas Electron Multiplier (GEM) and the Micro-strip Gas Chamber (MSGC), presenting two charge multiplication stages. For 2D-imaging, the GEM-like side (top side) is structured with strips orthogonal to the MSGC-like strips at the bottom side. Two thin orthogonal resistive lines of about 100 <formula formulatype="inline"><tex Notation="TeX">$\Omega$</tex></formula>, between the strips (top side) and between the anode strips (bottom side) allows us to obtain the actual position in both <formula formulatype="inline"><tex Notation="TeX">$x$</tex> </formula> and <formula formulatype="inline"><tex Notation="TeX">$y$</tex> </formula> directions. The four signals collected from the edges of the resistive lines are then digitized and processed with a computer. Charge gains of <formula formulatype="inline"><tex Notation="TeX">$10^{4}$</tex></formula> are obtained with the MHSP. Position resolutions of <formula formulatype="inline"><tex Notation="TeX">$\sigma_{x}=130\ \mu{\rm m}$</tex></formula> and <formula formulatype="inline"> <tex Notation="TeX">$\sigma_{y}=250\ \mu{\rm m}$</tex></formula> were achieved for 8-keV x-rays, making it suitable for many applications in single photon x-ray imaging. First x-ray images produced by the system are presented together with a discussion of the image quality and future prospects. </para>

Single photon counting X-ray imaging with Si and CdTe single chip pixel detectors and multichip pixel modules

Multichip modules (MCM) have been successfully built and operated. These use 4 single-photon counting MPEC 2.3 chips that are bump bonded to 1.3 cm /spl times/ 1.3 cm CdTe or Si semiconductor pixel sensors. Single-chip detectors were built as well. The MPEC 2.3 chip provides a pixel count rate up to 1 MHz with a large dynamic range of 18 bits, 2 counters and energy windowing with continuously adjustable thresholds. Each MPEC has 32 /spl times/ 32 pixels of 200 /spl mu/m /spl times/ 200 /spl mu/m pixel size. For a MCM the 4 chips are arranged in a 2 /spl times/ 2 array which leads to a 64 /spl times/ 64 sensor pixel geometry. The MCM construction is described, and the imaging performance of the different detectors is shown. A newly developed USB readout system has been used.

X-ray imaging with a silicon microstrip detector coupled to the RX64 ASIC

A single photon counting X-ray imaging system, with possible applications to dual energy mammography and angiography, is presented. A silicon microstrip detector with 100μm pitch strips is coupled to RX64 ASICs, each of them including 64 channels of preamplifier, shaper, discriminator and scaler. The system has low noise, good spatial resolution and high counting rate capability. Results on energy resolution have been obtained with a fluorescence source and quasi-monochromatic X-rays beams. Preliminary images obtained with an angiographic phantom are presented.

Room-temperature 2D X-ray imaging with the controlled-drift detector

The controlled-drift detector is a single-photon counting X-ray imaging silicon detector that features excellent energy and time resolution. Its distinctive feature is the readout of the signal charge packets stored in each pixel column by means of an electrostatic field in few /spl mu/s. The drift time of the charge packet identifies the pixel of incidence. Several one-dimensional flat images of single pixel columns have been acquired to investigate the achievable position resolution and the improvement of the energy resolution at high frame rates (up to 125 kHz). At 62.5 kHz, the room-temperature energy resolution at the Mn K/spl alpha/ line is better than 300 eV full-width at half-maximum. The first two-dimensional X-ray images of different masks carried out at frame frequencies in the range 10-100 kHz, both with radioactive and synchrotron light sources, will be presented.