The ISPA (Imaging Silicon Pixel Array)-tube is a position sensitive photon detector based on the hybrid technology. It detects light via a photocathode and an appropriate electric field accelerates ...the emitted photoelectrons towards a silicon pixel anode. This anode, finely segmented into pixel detectors provides binary images and allows for the self-triggering of the tube. Coupled to scintillating crystals, ISPA-tubes have been successfully tested in the field of gamma ray imaging, demonstrating real capabilities in both space and energy resolution. Recently, we have concentrated our efforts on the development of a compact and portable readout system based on new electronics and able to provide full control and real-time processing of ISPA-tubes. The system overview and the dedicated interface are presented in this paper.
Breast imaging with a dedicated PEM Ribeiro, R; Abreu, C; Almeida, P ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2004, Letnik:
527, Številka:
1-2
Journal Article
Recenzirano
During the last decade there was a growing interest on the application of Positron Emission Tomography, PET, techniques to Breast Imaging. More recently, preliminary results suggested the use of ...dedicated devices to Breast Imaging using the same technique, the so-called Positron Emission Mammography cameras, PEM. In this article we review the arguments leading to a dedicated instrument. Based on these arguments we describe the concept of a PEM camera under development within the Crystal Clear Collaboration and the first results of its expected performance in terms of sensitivity and position resolution.
In the present work we intend to assess the readout feasibility of Avalanche Photodiode (APD) detectors via long signal lines for the development of a combined small-animal PET-MR prototype based on ...the ClearPEM technology. The detection performance of a LYSO-APD module was evaluated reading out the APD charge signals to the front-end ASIC via an 80mm length flexible flat-cable (FFC). Experimental results showed a time resolution of 5.06ns for the detector module in double-readout mode, with a nonsignificant degradation of 8.4% with the introduction of the FFC. The energy resolution of the system was not degradated by the FFC.
We present an overview of the Clear-PEM breast imaging scanner. Clear-PEM is a unique dual-head Positron Emission Mammography scanner using APD-based detector modules that are capable of measuring ...depth-of-interaction (DOI) with a resolution of 2 mm in 20 mm long LYSO:Ce crystals. Such capability leads to an image spatial resolution of 1.2 mm and a high efficiency, foreseeing the detection of 3 mm breast lesions in less than 7 minutes exams. The full system comprises 192 detector modules in a total of 6144 LYSO:Ce crystals and 384 32-pixel APD arrays readout by ASICs with 192 input channels that represents an unprecedented level of integration in PET systems. Throughout the project and besides the detector module, we had developed dedicated Frontend and Data Acquisition electronics, the mechanical design and construction of the detector heads and the robotic gantry, as well as all the software that include calibration (energy, time and DOI), normalization and image reconstruction algorithms. In this work we will discuss the developments and present the commissioning results of the detector before the beginning of the clinical trials program, scheduled for the end of the present year.
Positron Emission based mammography systems are expected to constitute a significant breakthrough in the early diagnosis of breast cancer. This may lead to a significant enlargement in the horizon of ...women life, since breast cancer is considered to be among the most deadly types. With this purpose, a consortium has been built to develop a mammography PET system in the framework of the Clear-PEM Collaboration. The Clear-PEM scanner is a unique Positron Emission Mammography (PEM) scanner using APD-based detectors. It is capable of measuring Depth-of-Interaction (DoI) with a resolution of 2 mm in LYSO:Ce crystals, enabling a spatial resolution of 1.2 mm. An important part of the PEM scanner is a high-speed DAE (Data Acquisition Electronics) system. DAE has been developed to process and acquire data coming from the 12,288 front-end (FE) photo-detector channels. In this paper, an overview of this scanner (system and board-level electronics, mechanical design, service and image reconstruction software) is presented, focusing on the specification and implementation of the DAE which is responsible for real-time retrieving, analyzing, filtering and formatting the data coming from the front-end. The objective is to identify relevant data and after conditioning, according to pre-defined protocols, send the data to an acquisition PC for image reconstruction. Communication between DAE and PC is carried out using the S-Link (proprietary of CERN) protocol. Experimental results of validation and test of the DAE system are presented.
First experimental results of the imaging system Clear-PEM for positron emission mammography, under development within the framework of the Crystal Clear Collaboration at CERN, are presented. The ...quality control procedures of crystal pixels, APD arrays and assembled detector modules are described. The detector module performance was characterized in detail. Results on measurements of light yield, energy resolution, depth-of-interaction and inter-channel cross-talk are discussed. The status of the development of the front-end electronics and of the data acquisition boards is reported.
The design and evaluation of the imaging system Clear-PEM for positron emission mammography, under development by the PEM Consortium within the framework of the Crystal Clear Collaboration at CERN, ...is presented. The proposed apparatus is based on fast, segmented, high atomic number radiation sensors with depth-of-interaction measurement capabilities and state-of-the-art data acquisition techniques. The camera consists of two compact and planar detector heads with adequate field-of-view dimensions for breast and axilla imaging. Low-noise integrated electronics provide signal amplification and analog multiplexing based on a new data-driven architecture. The coincidence trigger and data acquisition architecture makes extensive use of pipeline processing structures and multi-event memories for high efficiency up to a data acquisition rate of one million events/s. Experimental validation of the detection techniques, namely the basic properties of the radiation sensors and the ability to measure the depth-of-interaction of the incoming photons, are presented. System performance in terms of detection sensitivity, count-rates and reconstructed image spatial resolution were also evaluated by means of a detailed Monte Carlo simulation and an iterative image reconstruction algorithm.
The Clear-PEM prototype under development aims to improve early stage breast cancer diagnostics. The proposed device is based on cerium doped lutetium crystal matrices developed by the Crystal Clear ...Collaboration, as well as on modern data acquisition techniques. A series of Monte Carlo studies were performed to evaluate detection sensitivity, background rate and intrinsic spatial resolution in order to optimize the final detector concept. A description of the developed GEANT4 based simulation framework and PEM image reconstruction software is also presented in this paper. First simulation results indicates that Clear-PEM design significantly increases detection sensitivity in comparison with conventional PET cameras for breast cancer diagnostics. Count-rate simulation results are within operation limits for the data acquisition system, able to read 1 MHz event rate, allowing to take full profit of the large detector acceptance.
Insect galectins are associated with embryonic development or immunity against pathogens. Here, we show that they can be exploited by parasites for survival in their insect hosts. PpGalec, a tandem ...repeat galectin expressed in the midgut of the sand fly
Phlebotomus papatasi, is used by
Leishmania major as a receptor for mediating specific binding to the insect midgut, an event crucial for parasite survival, and accounts for species-specific vector competence. PpGalec is thus identified as a key molecule controlling vector competence for the most widely distributed form of cutaneous leishmaniasis in the Old World. In addition, these studies demonstrate the feasibility of using midgut receptors for parasite ligands as target antigens for transmission-blocking vaccines.
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