Hybrid Semiconductor Pixel Detectors for Low‐ and Medium‐Energy<scp>X</scp>‐ and Gamma‐Ray Single Photon Imaging Using the Medipix Read‐Out Chip

Russo, Paolo

doi:10.1002/0471443395.img115

Cited by 16 publications

(9 citation statements)

References 48 publications

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“…Using the flip-chip technology, the readout chip is connected pixel by pixel via bump-bonding to a matching pixel detector to form a so-called hybrid detector. [2] This configuration has the advantage of optimizing separately the microelectronics technology (reduced pixel pitch, increased density of transistors per cell) implemented in the low resistivity silicon substrate of the ASIC, and the room temperature semiconductor pixel detector, implemented using material substrates like high-resistivity silicon, bulk or epitaxial GaAs, CdTe, and CdZnTe. Different semiconductors (elemental or compound), as well as different substrate thicknesses, can then be selected in order to cope with different application needs.…”

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confidence: 99%

First experimental tests with a CdTe photon counting pixel detector hybridized with a Medipix2 readout chip

Chmeissani

Fröjdh

Gal

et al. 2004

IEEE Trans. Nucl. Sci.

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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 256 256 square pixels, a pitch of 55 m, a sensitive area of 14 14 mm 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 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.

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confidence: 99%

First experimental tests with a CdTe photon counting pixel detector hybridized with a Medipix2 readout chip

Chmeissani

Fröjdh

Gal

et al. 2004

IEEE Trans. Nucl. Sci.

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“…For the Tc-99m (140 keV) gamma radiation detector we plan to use a 1 mm-thick CdTe pixel detector readout via the Medipix2 CMOS circuit [9] (256 256 pixels with 55 m pitch), a hybrid detector [10] used in single photon counting system; the Medipix2 ASIC will be interfaced serially via a MUROS2 board [11] or in parallel mode via a MPRS board [12] to a PC, running the Medisoft 4 software [13]. In the present prototype, however, we use the available first version of the chip (Medipix1) [14], which has 64 64 pixels with 170 m pitch (11 11 mm sensitive area), bump-bonded to a 300 m thick silicon detector.…”

Section: A Radionuclide Imagingmentioning

confidence: 99%

Preliminary tests of a prototype system for optical and radionuclide imaging in small animals

Celentano

Laccetti

Liuzzi

et al. 2003

IEEE Trans. Nucl. Sci.

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We have assembled a prototype system for multimodal (radionuclide and optical) in vivo planar imaging of small animals (mice) using single photon emission radiotracers (Tc-99m) and a fluorescent marker (hematoporphyrin). Preliminary tests of the separate (optical and radionuclide) prototype imaging systems are presented, aimed at assessing their features and at determining the experimental protocol for in vivo imaging. Tests were performed on anesthetized healthy or tumor bearing mice. The gamma radiation detector is a small area (11 11 mm 2 ) hybrid pixel detector based on the Medipix1 ASIC readout technology (64 64 square pixels of 170 m by side), bump-bonded to a 300 m thick silicon detector. High spatial resolution in radioimaging (in the order of 1 mm) is achieved in vivo with a pinhole tungsten collimator (0.35 mm diameter, 90 acceptance angle, field of view of over 20 mm at 10 mm source distance). A future setup will use the Medipix2 hybrid detector (256 256 square pixels, 55 m by side) bump-bonded to a 1 mm thick CdTe pixel detector. The laser-induced in vivo fluorescence imaging system comprises a pulsed light source (Nd : YAG laser, = 532 nm, energy/pulse = 30 mJ, pulse width = 50 ps, repetition rate = 10 Hz) used to excite the fluorescence emission (600-760 nm) of injected hematoporphyrin compound, a low sensitivity CCD camera and a commercial image analysis system. Images of normal and tumor regions are acquired by using a cut-on filter ( 600 nm). Digital image subtraction then enhances the tumor contrast with respect to the background. The final experimental protocol, only partly implemented here, includes independent and then combined optical/radio imaging of control mice and of a solid tumoral area (human thyroid derived anaplastic carcinoma) after injection of the radiotracer and/or of the fluorophore. In this work, the accumulation of the radionuclide in selected organs and of the fluorophore in the tumor provides the signal contrast in the two imaging modalities. Fluorescence spectroscopy of excised tissue samples is also performed to help the interpretation of fluorescence images. Results of in vivo combined imaging on tumor in mice will be shown in a next paper.

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“…Medipix series chip adds significant improvements to the previous Medipix1 version (1.0 µm CMOS, 64x64 pixel, 170 µm pitch, single charge polarity and single detection threshold, 15 bit counter), which has shown applications in all fields mentioned above [8]. Matrix [2,7] The Medipix2 chip is a complex Application Specific Integrated Circuit (ASIC) of about 2 cm 2 sensitive area which contains around 33 million transistors, with operative voltage levels set digitally via internal DACs and with both a serial and a parallel I/O bus.…”

Section: The Medipix2 Chip and Its Read-out Interfacesmentioning

confidence: 99%

Preliminary test of Medisoft 4: control software for the Medipix2 read-out chip

Maionino¹,

Mettivier²,

Montesi³

et al.

2002 IEEE Nuclear Science Symposium Conference Record

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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

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Hybrid Semiconductor Pixel Detectors for Low‐ and Medium‐EnergyX‐ and Gamma‐Ray Single Photon Imaging Using the Medipix Read‐Out Chip

Cited by 16 publications

References 48 publications

First experimental tests with a CdTe photon counting pixel detector hybridized with a Medipix2 readout chip

First experimental tests with a CdTe photon counting pixel detector hybridized with a Medipix2 readout chip

Preliminary tests of a prototype system for optical and radionuclide imaging in small animals

Preliminary test of Medisoft 4: control software for the Medipix2 read-out chip

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