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Study of 3D position determination of the interaction point in monolithic scintillator blocks for Positron Emission Tomography

Thursday, 5 May, 2011 - 16:00
Campus: Brussels Humanities, Sciences & Engineering campus
Faculty: Science and Bio-engineering Sciences
Zhi Li
phd defence

Positron emission tomography (PET) is a nuclear medicine imaging
technique based on the detection of gamma rays emitted by positronemitting
isotopes. It is one of the noninvasive technologies, which can be
used as a diagnostic tools to detect tumors, neurological disorders and
heart problems, etc, as well as a research tool in e.g. pre-clinical testing
on laboratory animals, mapping brain functions, ...

A very important parameter in the design of PET scanners is the accuracy
and efficiency with which the gamma photons can be localized by the
detectors in the scanner. The goal of this thesis is to improve the
performance of an upcoming detector concept for PET based on
monolithic scintillation crystals.

This thesis presents a study of possible models to describe the relation
between the scintillation light point-of-origin and the measured photo
detector pixel signals in monolithic scintillation crystals. From the model,
the X, Y and depth of interaction (DOI) coordinates can be estimated
simultaneously by nonlinear least-square fitting.

This model was evaluated using simulation and experimental data by
positioning a beam of 511 keV photons at known positions on the
20*20*10 mm LSO block. The results compare favorably to two other
algorithms, maximum likelihood and neural networks. In addition the
new method depends only on the information embedded in the signals of
individual events, and therefore does not need any prior position training
or calibration.

PDF icon Li_a.pdfPDF icon Li_i.pdf