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We are implementing an X-ray breast Computed Tomography (CT) system on the gantry of a dedicated single photon emission tomography system for breast Tc-99 imaging. For the breast CT system we investigated the relevance of the beam hardening artifact. We studied the use of a single photon counting silicon pixel detector (0.3 mm thick, 256 � 256 pixel, 55mm pitch, bump-bonded to the Medipix2 photon counting readout chip) as detector unit in our X-ray CT system. We evaluated the beam hardening ‘‘cupping’’ artifact using homogeneous PMMA slabs and phantoms up to 14 cm in diameter, used as uncompressed breast tissue phantoms, imaged with a tungsten anode tube at 80 kVp with 4.2 mm Al filtration. For beam hardening evaluation we used a bimodal energy model. The CT data show a ‘‘cupping’’ artifact going from 4% (4-cm thick material) to 18% (14-cm thick material). This huge artifacts is influenced by the low detection efficiency and the charge sharing effect of the silicon pixel detector. r 2007 Published by Elsevier B.V. PACS: 85.57.cp; 87.57.Q

An imaging system based on the Medipix2, a single photon counting pixel readout ASIC for X-ray hybrid detectors, has been developed for tomography imaging applications. The “quad assembly” houses four Medipix2 chips placed in a 2×2 array with an active area of about 3×3 cm 2 . The readout system we present consists of four electronic cards and exploits the Medipix2 parallel readout mode and a fast optical link based on the Glink standard, giving high flexibility and EM interference immunity over long distance connections. A PCI board interfaces the imaging system to a standard PC. We expect a frame rate of 25 frame/s which allows real-time X-ray imaging acquisitions and fast computed tomography (CT) scanning. In this paper, we describe the DAQ project and the status of development.

We describe MediSPECT, a new scanner developed at University and INFN Napoli, for SPECT studies on small animals with a small field of view (FOV) and high spatial resolution. The CdTe pixel detector (a 256×256 matrix of 55 μm square pixels) operating in single photon counting for detection of gamma-rays with low and medium energy (e.g. 125 I, 27–35 keV, 99m Tc, 140 keV), is bump bonded to the Medipix2 readout chip. The FOV of the MediSPECT scanner with a coded aperture mask collimator ranges from 6.3 mm (system spatial resolution 110 μm at 27–35 keV) to 24.3 mm. With a 0.30 mm pinhole the FOV ranges from 2.4 to 29 mm (where the system spatial resolution is 1.0 mm at 27–35 keV and 2.0 mm at 140 keV). MediSPECT will be used for in vivo imaging of small organs or tissue structures in mouse, e.g., brain, thyroid, heart or tumor.

Using a silicon pixel detector we have developed an imaging probe for intraoperative detection of tumor masses labeled with 18 F-Fluorodeoxyglucose ( 18 FDG) positron emitting radiotracer. The design goal is high efficiency for positron detection from tumor tissue and high rejection of the γ-ray background (511 keV annihilation quanta), coupled to imaging capabilities with submillimeter resolution. In this paper, we report on initial tests of the detector unit (linearity, sensitivity, spatial resolution, γ to β + ratio), based on a room temperature silicon pixel detector (300 μm thick, ∼2 cm 2 sensitive area) with 256×256 pixels of 55 μm pitch, coupled to the Medipix2 readout circuit. The laboratory tests carried out using 18 FDG droplets showed counting linearity in the range 37–37,000 Bq, a sensitivity for (γ+β + ) of 0.35 cps/Bq, an intrinsic spatial resolution of 230±5 μm with the source in contact with the detector, and a ratio γ/β + of about 2% due to annihilation quanta.

The OPERA experiment was designed to search for $\nu_{\mu} \rightarrow \nu_{\tau}$ oscillations in appearance mode, i.e. by detecting the $\tau$-leptons produced in charged current $\nu_{\tau}$ interactions. The experiment took data from 2008 to 2012 in the CERN Neutrinos to Gran Sasso beam. The observation of $\nu_{\mu} \rightarrow \nu_{\tau}$ appearance, achieved with four candidate events in a sub-sample of the data, was previously reported. In this paper, a fifth $\nu_{\tau}$ candidate event, found in an enlarged data sample, is described. Together with a further reduction of the expected background, the candidate events detected so far allow assessing the discovery of $\nu_{\mu}\rightarrow \nu_{\tau}$ oscillations in appearance mode with a significance larger than 5 $\sigma$., Comment: 7 pages, 3 figures

We devised a multimodal planar imaging system for in vivo mouse imaging, employing four modalities: optical imaging, green and red fluorescence reflectance imaging, radionuclide imaging and X-ray radiography. We are testing separately, and then in a combined way, each detection mode, via in vivo mouse imaging, with the final purpose of identifying small implanted tumor masses, of providing early tumor detection and following metastatic dissemination. We describe the multimodal system and summarize its main performance, as assessed in our research work in the various stages of the development, in fluorescence and radionuclide tests on healthy or tumor bearing mice. For gamma-ray detection we used a semiconductor pixel detector (Medipix1 or Medipix2) that works in single photon counting. Laser-induced fluorescence reflectance imaging was performed in vivo using a pulsed light source to excite the fluorescence emission of injected hematoporphyrin (HP) compound, a CCD camera, a low pass filter and a commercial image analysis system. The bimodal system was used for the acquisition of combined images of the tumor area (fluorescence: animal top view; radionuclide: bottom view). It was shown that the tumor area can be imaged in a few minutes, with a few millimeter resolution (1 mm pinhole diameter), radioactively (99mTc radiotracer), and with the fluorescence system and that, in one case, only one of the two modalities is able to recognize the tumor. A phantom study for thyroid imaging with 125I source embedded in a simulated tissue indicated a spatial resolution of 1.25 mm FWHM with a 1 mm pinhole.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We report on high frame rate X-ray imaging tests with the Medipix2 single photon counting detector (single frames contain 256times256 pixel, 55 mum pitch, 13 bit counter) bump-bonded to a 300 mum thick silicon pixel detector. Image data are readout serially at a maximum frequency of 86 MHz, and each image frame corresponds to about 1 Mbit. After implementing a new version of the dedicated Medisoft 4.1 software for the operation of the Medipix2 imaging system, the maximum possible frame rate increased from a few frame per second up to 51 fps (10% duty cycle). Dynamic imaging tests have been made by irradiating with a X-ray tube (25 kV, 1 mA) an absorbing edge being translated at constant speed. Applications of this new option for the Medipix2 imaging system are in the fields of cineradiography, dynamic X-ray imaging, and synchrotron radiation imaging

We report on tests of a combined fluorescence and radionuclide planar imaging system for in vivo investigation on small animals. Combined images of anaesthetized mice bearing a surface solid tumor are presented. The fluorescent marker is a hematoporphyrin compound laser-excited with green light and imaged in the red fluorescence emission with a standard monochrome charge coupled device (CCD) camera. The gamma-ray (/sup 99m/Tc) pinhole imaging system uses a semiconductor pixel detector obtained by hybridizing a Silicon (300-/spl mu/m thick) or a CdTe (1-mm thick) pixel detector to the Medipix2 (55-/spl mu/m pitch) readout integrated circuit for single photon counting. The acquisition of combined images of the tumor area (fluorescence: animal top view; radionuclide: bottom view) shows that the tumor area can be imaged in a few minutes, with a few millimeter resolution (1-mm pinhole diameter), radioactively (/sup 99m/Tc MIBI, 74 MBq), and with the optical system. Combined imaging revealed also a different uptake of the two types of tumors studied (one grown from anaplastic human thyroid carcinoma-derived cells, the other from human papillary carcinoma-derived cells). Future progress will be toward a more compact optical setup and the use of a thicker CdTe detector.

We report on the first measurements of 3 H beta autoradiography obtained using a room temperature hybrid pixel detector, consisting of the Medipix2 single particle counting read-out chip bump-bonded to a 300 μm thick silicon pixel detector. This system has 256×256 square pixels of 55 μm pitch for a total sensitive area of 14×14 mm 2 . Each pixel contains a double threshold discriminator and a 13-bit counter. Using a detection threshold equivalent to less than 6 keV and a background count rate of 5×10 −3 counts mm −2 s −1 , with exposures up to several hours, real-time images have been obtained of tritium-labeled solution drops spotted on a thin mylar foil placed in contact with the continuous top electrode of the silicon detector, in open air condition.

In the framework of the MAMA project, funded by INFN, we have assembled a digital imaging system for beta and gamma autoradiography based on the Medipix2 single photon counting read-out chip bump-bonded to a 300 μm thick silicon pixel detector. This system has 256×256 square pixels of 55 μm pitch for a total sensitive area of 14×14 mm2. Each pixel contains two discriminators and a 13-bit counter. The detection threshold is about 6 keV and a noise is about 10−3 cps/mm2. Real time images have been obtained of 3H and 14C autoradiographic scales. The minimum detectable activity is 0.32 Bq in 14 h for 3H and 0.012 Bq in 10 h for 14C.

We present preliminary tests of hybrid pixel detectors consisting of the Medipix2 readout chip bump-bonded to a 1-mm-thick CdTe pixel detector. This room temperature imaging system for single photon counting has been developed within the Medipix2 European Collaboration for various imaging applications with X-rays and gamma rays, including dental radiography, mammography, synchrotron radiation, nuclear medicine, and radiation monitoring in nuclear facilities. The Medipix2 + CdTe hybrid detector features 256 /spl times/ 256 square pixels, a pitch of 55 /spl mu/m, a sensitive area of 14/spl times/14 mm/sup 2/. We analyzed the quality of the detector and bump-bonding and the response to nuclear radiation of the first CdTe hybrids. The CdTe pixel detectors, with Pt ohmic contacts, showed an ohmic response when negatively biased up to less than 60 V (electrons collection mode). Tests were also performed in holes collection mode, where a nonresistive behavior was observed above +15 V. We performed a series of imaging tests at low voltage bias with gamma radioactive sources and with an X-ray tube. Under uniform irradiation, we observed for all detectors the presence of numerous, stable structures in the form of small circles of about 200 /spl mu/m diameter, with the central pixels showing a reduced counting efficiency with respect to the periphery (in electrons counting regime). Also long filament structures have been observed. Further investigations will reveal whether they are due to an intrinsic detector response (e.g., due to Te inclusions) or to the bump-bonding process.

In this paper we describe the design, fabrication and testing of an active endoscope for minimal invasive surgery (MIS). The device has a silicone rubber body with 8 mm outer diameter and 40 mm length. This configuration has two bending degrees of freedom. The device is actuated by three miniature SMA springs, which are heated by Joule effect and cooled by a forced air flow. The actuators are located in three lumina (1.5 mm diameter) of the endoscope. The active endoscope incorporates a fibre optic bundle for visual inspection which has been used in the current experiments to measure the performance of the endoscope tip in terms of bending angles and directivity.

We have developed a technique and a prototype for /spl beta/-rays and /spl gamma/-rays quantitative imaging of biological samples which have been radioactively labeled. The prototype is based on a solid state pixel detector, bump-bonded to a low threshold, single particle counting chip: the detector we used is 200-/spl mu/m thick GaAs, with pixel size 170 /spl mu/m. In this paper we describe an experiment that shows the capability of monitoring a dynamic process. Specifically, [/sup 14/C]L-Leucine uptake by eggs of mollusk cephalopod Octopus vulgaris and the consequent migration of marker into the ooplasm was followed.

We present here preliminary tests of Medisoft 4, a software procedure for the control and the read-out of the single photon counting radiation imaging systems based on the Medipix2 chip (256×256 pixels, 55 μm pitch). The system has been developed in the framework of the Medipix2 collaboration. This hardware and software system is the successor of the system based on the Medipix1 photon counting chip (64×64 pixels, 170 μm pitch). Following the Medipix system evolution, Medisoft 4 allows the user to access the new implemented features, such as the higher resolution, the faster data communication rates, the daisy-chain multichip mode, the energy windowed acquisition, the continuous acquisition mode, the double signal polarity (holes and electrons), etc. The readout of the data from the Medipix2 chip is presently via the chip serial bus through a MUROS2 interface board and a commercial I/O board, but parallel read-out via a MPRS dedicated interface is also foreseen. The current version (Medisoft 4.0) - here the subject of preliminary tests connected via MUROS2 to a Medipix2 chip not bump-bonded to any detector - reads out only single chips and features a reduced set of functionalities. Future versions will read up to eight chips in daisy chain and provide full system performance, including high frame rate acquisitions and spectroscopic imaging. After description of the Medipix2 chip, its read-out interfaces and the Medisoft 4 software architecture, we show the results of preliminary software tests on serial communication protocol and speed with MUROS2 and Medipix2, analogue test-input, internal DACs calibration, threshold uniformity.

We present some additional results obtained with the BETAview system, a digital system for real time /spl beta/-imaging based on semiconductor pixel detectors and on a single photon counting read-out chip. In this paper, we describe the system assembled with a Si detector, 300 /spl mu/m thick, segmented into 64/spl times/64 square pixels with 170 /spl mu/m pitch. The solid state pixel array detector is bump-bonded pixel by pixel to a low threshold, single particle counting electronics, the photon counting chip (PCC) developed by the Medipix1Collaboration for biomedical applications. Each cell (corresponding to a detector pixel) of the front-end chip has a maximum count rate of 2 MHz, a minimum nominal threshold of 1400 e~ (corresponding to about 5 keV in Si) and contains a 15-bit counter. The detector sensitive area is about 1 cm/sup 2/, but several detectors could be assembled in arrays. The measured background counts were about 3.5/spl middot/10/sup -2/ cps/cm/sup 2/, which implies a very high sensitivity of the device. The detection threshold used in this experiment was 15 keV. In this paper we show the results obtained in the real time monitoring of two biological dynamic processes: an amino acid uptake and the thermal denaturation process of oligonucleotides. Specifically, we have followed over time the accumulation of a marked amino acid ([/sup 14/C]L-Leucine) into Octopus vulgaris eggs cells. After about 20 min from the beginning of the uptake process, the radioactively marked eggs become clearly visible over the background culture radioactive medium. We also describe the successful performance of the /spl beta/-imaging system in genetic studies involving the real time reconstruction of denaturation and kinetics curves for two different /sup 32/P-radiolabeled nucleotides.

We present a digital autoradiography (DAR) system, named BETA view , based on semiconductor pixel detectors and a single particle counting chip, for quantitative analysis of β-emitting radioactive tracers in biological samples. The system is able to perform a real time monitoring of time-dependent biological phenomena. BETA view could be equipped either with GaAs or with Si semiconductor pixellated detectors. In this paper, we describe the results obtained with an assembly based on a Si detector, 300 μm thick, segmented into 64×64 170 μm size square pixels. The detector is bump-bonded to the low threshold, single particle counting chip named Medipix1, developed by a CERN-based European collaboration. The sensitive area is about 1 cm 2 . Studies of background noise and detection efficiency have been performed. Moreover, time-resolved cellular uptake studies with radiolabelled molecules have been monitored. Specifically, we have followed in vivo and in real time, the [ 14 C] l -leucine amino acid uptake by eggs of Octopus vulgaris confirming the preliminary results of a previous paper. This opens the field of biomolecular kynetic studies with this new class of semiconductor DAR systems, whose evolution (using the Medipix2 chip, 256×256 pixels, 55 μm pixel size) is soon to come.

We are investigating the feasibility of an intraoperative imaging probe for lymphoscintigraphy withTc-99m tracer, for sentinel node radioguided surgery, using the Medipix series of hybrid detectors coupled to a collimator. These detectors are pixelated semiconductor detectors bump-bonded to the Medipix1 photon counting read-out chip (64x64 pixel, 170 mm pitch) or to the Medipix2 chip (256x256 pixel, 55 um pitch), developed by the European Medipix collaboration. The pixel detector we plan to use in the final version of the probe is a semi-insulating GaAs detector or a 1–2mm thick CdZnTe detector. For the preliminary tests presented here, we used 300-um thick silicon detectors, hybridized via bump-bonding to the Medipix1 chip. We used a tungsten parallel-hole collimator (7mm thick, matrix array of 6464 100 mm circular holes with 170 um pitch), and a 22, 60 and 122 keV point-like (1mm diameter) radioactive sources, placed at various distances from the detector. These tests were conducted in order to investigate the general feasibility of this imaging probe and its resolving power. Measurements show the high resolution but low efficiency performance of the detector–collimator set, which is able to image the 122 keV source with

Muon Radiography allows to map the density of a volcanic cone. It is based on the measurement of the attenuation of the flux of muons present in the cosmic radiation on the ground. The MU-RAY project has developed an innovative detector designed for the muon radiography. The main features are the low electric power consumption, robustness and transportability, good spatial resolution and muon time of flight measurement. A 1 m2 detector prototype has been constructed. and collected data at Mt. Vesuvius for approximately 1 month in spring 2013. A second campaign of measurement has been performed at the Puy de Dome, France, in the last four months of 2013. In this article the principles of muon radiography, the MU-RAY detector and the first results from the collected data will be described.

We present an autoradiography system (BETAview) for a quantitative analysis of radioactive markers in biological samples; this system is also able to monitor a dynamic process. It is based on a solid-state pixel array detector, bump bonded to low threshold, integrated electronics developed for medical applications (Medipix). The present assembly is equipped with a 200 μm thick GaAs square detector, about 1 cm side, segmented into 64×64 170-μm size square pixels; simulation and experimental studies show good linearity and high sensitivity to β sources. Imaging tests with β sources of medical and biological interest such as 14C, 35S, 32P are reported.

In the framework of the development of a digital radiography/autoradiography system using solid state detectors, we studied the performance of GaAs pixellated detectors regarding noise level and detection behavior of interpixel space. The detector is a 64×64 pixel array, 200 μm thick GaAs, 150 μm contact size and 20 μm interpixel space. Studies involve I – V curves, detector behavior for long-period biasing, noise as a function of temperature, and possible detection efficiency loss due to interpixel dead spaces.

Although silicon planar technology has generated the field of micromechanics, it has been realized that this technology has intrinsic limitations for the fabrication of truly so micromechanisms. A number of alternative technologies based either on silicon or on different materials are presently investigated in order to overcome the limitations of planar silicon technology. This paper outlines the motivations for developing new microfabrication technologies, especially those that are considered as 'non-traditional' in the microelectronics domain, and the perspectives offered by this approach for fabricating miniature, micro and nanodevices. Four representative 'non-traditional' technologies are considered. LIGA process, micro electro-discharge machining (EDM), micro stereo lithography, and the combination of biological and artificial microfabricated structures ('hybrid' technologies).

The authors present a critical survey of some representative technologies which are candidates for the development of microactuators for microrobots. Since the field of 'microrobotics' is an entirely new one, some concepts and definitions are given first; in particular, a distinction between 'micromachines' and 'microrobots' is proposed. Then, a further classification is proposed between three different types of robots: the 'miniature' robot, the 'microrobot' and the 'nanorobot', and their expected performances and fields of applications are discussed. The need for developing dedicated miniature actuators and microactuators emerges clearly from this discussion, together with the main requirements for this class of 'new' actuators. Finally, some significant examples of implementation of microactuators are illustrated, and the main advantages and limitations of each technology are discussed.

In vivo macroscopic optical imaging measurements on anesthetized mice bearing a solid human surface tumor (thyroid carcinoma ARO/NPA) have been performed following the administration of a water solution of a fluorescent marker (hematoporphyrin dichlorohydrate). ©2005 Optical Society of America.

We present here Medisoft 4, a software procedure for the control and the readout of an imaging system in the form of a hybrid pixel detector (256/spl times/256 pixels, 55 /spl mu/m pitch) developed in the framework of the Medipix2 collaboration. This system, originally designed for biomedical applications, is based on the single-photon counting Medipix2 read-out chip, the MUROS-2 interface board and a commercially available digital I/O board. Following the Medipix2 system evolution from its first version (Medipix1, 64/spl times/64 pixels, 170 /spl mu/m pitch), the Medisoft 4 software system allows the user to access the new implemented features, such as the higher spatial resolution, the faster chip-to-PC communication, the daisy-chain multichip read-out mode, the energy-windowed acquisition and the continuous acquisition mode. We describe here the software architecture, the complete file system, the software functions and features.

A new digital imaging system for beta and gamma autoradiography has been realized. The technological advancement of this imaging system is represented by the second-generation Medipix2 chip (a single photon/particle counting chip), developed at CERN in the framework of the Medipix2 European collaboration, as a successor of the Medipix1 chip. Medipix2 is realized in 0.25 /spl mu/m CMOS technology; it has a sensitive area of 14/spl times/14 mm/sup 2/ and a pixel pitch of 55 /spl mu/m, it has been bump-bonded to a 300 /spl mu/m thick silicon pixel detector. A dedicated electronic interface and a complete image acquisition and processing software allow to operate this hybrid pixel detector for digital autoradiography with acquisition time as long as several days. In a preliminary test of this imaging system for digital autoradiography we obtained a detection threshold of 1600 electrons (equivalent to about 6 keV in Si), a noise of 10/sup -3/ cps/mm/sup 2/, a minimum detectable activity of 0.32 Bq in 14 h for /sup 3/H and 0.012 Bq in 10 h for /sup 14/C. A preliminary spatial resolution test for /sup 14/C gives a FWHM resolution of 30 /spl mu/m. Real time images of /sup 3/H, /sup 14/C, /sup 125/I autoradiographic microscales are also presented.