- / The term Molecular Imaging (MI) can be broadly defined as the in vivo characterization and
measurement of biological processes at the cellular and molecular level. In contradistinction to
“classical” diagnostic imaging, it sets forth to probe the molecular abnormalities that are the basis of
disease rather than to image the end effects of these molecular alterations. The underlying biology
represents a new arena for many researchers. A number of technological challenges such as signal
amplification, data and image processing and efficient imaging strategies, provide a fast growing
scientific domain. Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), Single
Photon Emission Tomography (SPECT) and optical imaging are the main tools of clinical molecular
imaging. Nuclear medicine techniques (SPECT and PET) are key players in MI. New
radiopharmaceutical products are currently being developed, in order to increase the specificity and
sensitivity of existing imaging techniques. Small animal imaging is the main tool for the evaluation of
those derivatives, especially in dynamic in vivo studies. In this, preclinical part, high resolution and
high sensitivity imaging equipment is necessary; as a result a number of such prototypes have been
developed worldwide and some of them are commercialized. However, there cost is usually not
affordable for small or medium size laboratories.
In this work a low cost dual head PET camera, suitable for high resolution small animal studies
has been developed. It is the result of the collaboration between Jefferson lab and Technological
Educational Institute of Athens (TEI) and is currently evaluated in Institute of Radioisotopes and
Radiodiagnostic Products (IRRP), in “Demokritos” Center.
The system has a field of view of 5x5cm and is based on 2 H8500 position sensitive
photomultiplier tubes (PSPMTs), coupled to two LSO crystals with 2.5x2.5mm pixel size. Then an
FPGA based data acquisition system and proper data reconstruction system collect events, sort
coincidences and produce images. The DAQ board consists of 16-channel DAQ modules installed on a
USB2 carrier. Each channel is an independent acquisition system consisting of traditional analog pulse
processing, FPGA analog control, and FPGA signal processing. After acquisition and processing,
channel data are assembled into event blocks for readout by the carrier board. Application specific tasks
are performed in JAVA using the Kmax interface. The GUI was designed to be easy-to-use. In order to
further analyze images and process the results proper algorithms were developed in MATLAB and
ImageJ. Systems evaluation has been carried out using FDG. Point sources have been used for systems
calibration. Capillaries with 1.1mm inner diameter were imaged and used for resolution calculation.
Finally a mouse injected with 100μCi of FDG was imaged. Spatial resolution has been measured using
thin capillaries (1.1mm inner diameter) and found equal to 3,5mm in planar mode. This lower limit is
determined by LSO pixels size (2.5×25mm2). Simulation studies have shown that resolution lower than
2mm will be achieved in tomographic mode. Mice injected with FDG are presented. Brain and heart
are clearly imaged.
Currently, a rotating base is constructed, in order to upgrade the system to a tomographic PET.
PET results will be presented as well. In addition, IRRP and TEI are working on new
radiopharmaceuticals based on Cu-64. It must be stated that PET market opened in Greece four years
ago; This system is the first working small PET prototype in Greece and it initiates national preclinical
PET research.
Identifer | oai:union.ndltd.org:upatras.gr/oai:nemertes:10889/1314 |
Date | 06 February 2009 |
Creators | Ευθυμίου, Νικόλαος |
Contributors | Παναγιωτάκης, Γιώργος, Efthimiou, Nikolaos, Παναγιωτάκης, Γιώργος, Βασιλάκος, Παύλος, Σακελλαρόπουλος, Γιώργος |
Source Sets | University of Patras |
Language | English |
Detected Language | English |
Type | Thesis |
Rights | 0 |
Relation | Η ΒΥΠ διαθέτει αντίτυπο της διατριβής σε έντυπη μορφή στο βιβλιοστάσιο διδακτορικών διατριβών που βρίσκεται στο ισόγειο του κτιρίου της. |
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