Comparison of three types of XPAD3.2/CdTe single chip hybrids for hard X-ray applications in material science and biomedical imaging

The CHIPSPECT consortium aims at building a large multi-modules CdTe based photon counting detector for hard X-ray applications. For this purpose, we tested nine XPAD3.2 single chip hybrids in various configurations (i.e. Ohmic vs. Schottky contacts or electrons vs. holes collection mode) in order to select the most performing and best suited configuration for our experimental requirements. Measurements have been done using both X-ray synchrotron beams and 241Am source. Preliminary results on the image quality, calibration, stability, homogeneity and linearity of the different types of detectors are presented

A large surface X-ray camera based on XPAD3/CdTe single chip hybrids

iWoRiD’2015, 17th International Workshop on Radiation Imaging Detectors, Jun 2015, DESY, Hamburg, Germany.International audienceThe XPAD3 chip bump-bonded to a Si sensor has been widely used in preclinical microcomputedtomography and in synchrotron experiments. Although the XPAD3 chip is linear up to60 keV, the performance of the XPAD3/Si hybrid detector is limited to energies below 30 keV, forwhich detection efficiencies remain above 20%. To overcome this limitation on detection efficiencyin order to access imaging at higher energies, we decided to develop a camera based on XPAD3single chips bump-bonded to high-Z CdTe sensors. We will first present the construction of this newcamera, from the first tests of the single chip hybrids to the actual mechanical assembly. Then, wewill show first images and stability tests performed on the D2AM beam line at ESRF synchrotronfacility with the fully assembled camera

K-edge imaging with the XPAD3 hybrid pixel detector, direct comparison of CdTe and Si sensors

International audienceWe investigate the improvement from the use of high-Z CdTe sensors for pre-clinical K-edge imaging with the hybrid pixel detectors XPAD3. We compare XPAD3 chips bump bonded to Si or CdTe sensors in identical experimental conditions. Image performance for narrow energy bin acquisitions and contrast-to-noise ratios of K-edge images are presented and compared. CdTe sensors achieve signal-to-noise ratios at least three times higher than Si sensors within narrow energy bins, thanks to their much higher detection efficiency. Nevertheless Si sensors provide better contrast-to-noise ratios in K-edge imaging when working at equivalent counting statistics, due to their better estimation of the attenuation coefficient of the contrast agent. Results are compared to simulated data in the case of the XPAD3/Si detector. Good agreement is observed when including charge sharing between pixels, which have a strong impact on contrast-to-noise ratios in K-edge images

Physical Characterization of a Wireless Radiotracer Detection System Based on Pixelated Silicon for in Vivo Brain Studies in Freely Moving Rats

BLUPS for the four phenotypic traits studied. Each row corresponds to one individual

A wireless beta-microprobe based on pixelated silicon for in vivo brain studies in freely moving rats

The investigation of neurophysiological mechanisms underlying the functional specificity of brain regions requires the development of technologies that are well adjusted to in vivo studies in small animals. An exciting challenge remains the combination of brain imaging and behavioural studies, which associates molecular processes of neuronal communications to their related actions. A pixelated intracerebral probe (PIXSIC) presents a novel strategy using a submillimetric probe for beta+ radiotracer detection based on a pixelated silicon diode that can be stereotaxically implanted in the brain region of interest. This fully autonomous detection system permits time-resolved high sensitivity measurements of radiotracerswith additional imaging features in freelymoving rats. An application-specific integrated circuit (ASIC) allows for parallel signal processing of each pixel and enables the wireless operation. All components of the detector were tested and characterized. The beta+ sensitivity of the system was determined with the probe dipped into radiotracer solutions.Monte Carlo simulations served to validate the experimental values and assess the contribution of gamma noise. Preliminary implantation tests on anaesthetized rats proved PIXSIC's functionality in brain tissue. High spatial resolution allows for the visualization of radiotracer concentration in different brain regions with high temporal resolution. (Some figures may appear in colour only in the online journal

Physical Characterization of a Wireless Radiotracer Detection System Based on Pixelated Silicon for in Vivo Brain Studies in Freely Moving Rats

An exciting challenge for neuro-physiological investigations remains the combination of brain imaging and behavioral studies, which associates molecular processes of neuronal communications to their related actions. PIXSIC presents novel strategy using a submillimeter pixellated probe for β+ radiotracer detection based on a reverse-biased, high-resistivity silicon diode; This fully autonomous detection system permits local, time resolved measurements of radiotracers in a volume of a few mm3 with the probe dipped into aqueous solutions of [18F] and [11C]. Preliminary implantation tests on a anaesthetized rats proved functionality of the PIXSIC probe in brain tissues. High spatial resolution allows for the visualization of radiotracer concentration in different brain regions with a temporal resolution of less than 2 second