Since the first introduction of reconstructive tomography in medicine more than a decade ago, research into this technique has continued to arrest the interest of a growing number of scientists especially in the area of industrial non-destructive testing. It is thus an advantage for a laboratory to have a test rig that combines the various Imaging modalities using ionising radiations. Such a test rig has been designed and built around a BBC-B microcomputer complete with its own display system. It combines the ability for transmission and emission tomography with a capability for Compton scattering imaging. Imaging characteristics of the rig including the detectors efficiency, response, collimating systems line spread functions, resolution and the modulation transfer functions are determined. A model has been established to numerically calculate accurately the scattering volume and predict the scattering field at any scattering angle for bore-hole type of collimation. Images of aluminium phantom with lead and brass inclusions have been used to demonstrate the particular suitability of the Compton scattering technique for detecting dense materials within a low density medium. The use of an attenuation correction method for the scattered photons has proved very successful in improving contrast and signal-to-noise ratio of the images. None of the established imaging methods has proved capable of elemental distribution analysis and the methods used in elemental analysis lack the spatial information provided in imaging. A new and novel method is presented in this work that combines the elemental capability of neutron activation analysis with the spatial information of emission tomography. This method has been termed neutron induced gamma-ray emission tomography (NIGET). NIGET images obtained of a freeze-dried water pellet, a piece of human tibia and a study of the diffusion of a preservative solution in a sample of Scots-pine, have been used to demonstrate the potentials of this method.

Thesis (Ph. D.)--University of Technology, Sydney, 2004. / Bibliography: leaves 238-269.

The benefits of the computed tomography in the forensic medicine Radiological imaging methods represent one of the complementary examination methods supplementing conventional autopsy in addition to histological, toxicological, biochemical, microbiological, and serological examination in forensic medicine. The basic and commonly available radiological imaging method in forensic practice is X-ray imaging. With the development of modern radiological imaging methods (especially computed tomography and nuclear magnetic resonance), these modern methods have been gradually applied to the field of forensic medicine. The rapid development of radiological imaging methods in recent years (especially computed tomography and nuclear magnetic resonance) has caused the gradual application of these modern methods in the field of forensic medicine. Post mortem CT (pmCT) examination is now a common part of forensic medicine in the most developed world countries (Switzerland, Denmark, Australia, Japan, Germany, Italy, France and others) and since 2015 this examination has been available at two departments of forensic medicine in the Czech Republic. The primary aim of the study was to evaluate the benefits of pmCT examination in routine forensic practice in three comprehensive groups of individuals who died as a result of...

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Positron emission tomography (PET) is a well-established functional imaging method used in nuclear medicine. It allows for retrieving information about biochemical and physiological processes in vivo. The currently possible spatial resolution of PET is about 5 mm for brain acquisitions and about 8 mm for whole-body acquisitions, while recent improvements in image reconstruction point to a resolution of 2 mm in the near future. Typical acquisition times range from minutes to hours due to the low signal-to-noise ratio of the measuring principle, as well as due to the monitoring of the metabolism of the patient over a certain time. Therefore, patient motion increasingly limits the possible spatial resolution of PET. In addition, patient immobilisations are only of limited benefit in this context. Thus, patient motion leads to a relevant resolution degradation and incorrect quantification of metabolic parameters. The present work describes the utilisation of a novel motion compensation method for clinical brain PET acquisitions. By using an external motion tracking system, information about the head motion of a patient is continuously acquired during a PET acquisition. Based on the motion information, a newly developed event-based motion compensation algorithm performs spatial transformations of all registered coincidence events, thus utilising the raw data of a PET system - the so-called `list-mode´ data. For routine acquisition of this raw data, methods have been developed which allow for the first time to acquire list-mode data from an ECAT Exact HR+ PET scanner within an acceptable time frame. Furthermore, methods for acquiring the patient motion in clinical routine and methods for an automatic analysis of the registered motion have been developed. For the clinical integration of the aforementioned motion compensation approach, the development of additional methods (e.g. graphical user interfaces) was also part of this work. After development, optimisation and integration of the event-based motion compensation in clinical use, analyses with example data sets have been performed. Noticeable changes could be demonstrated by analysis of the qualitative and quantitative effects after the motion compensation. From a qualitative point of view, image artefacts have been eliminated, while quantitatively, the results of a tracer kinetics analysis of a FDOPA acquisition showed relevant changes in the R0k3 rates of an irreversible reference tissue two compartment model. Thus, it could be shown that an integration of a motion compensation method which is based on the utilisation of the raw data of a PET scanner, as well as the use of an external motion tracking system, is not only reasonable and possible for clinical use, but also shows relevant qualitative and quantitative improvement in PET imaging. / Die Positronen-Emissions-Tomographie (PET) ist ein in der Nuklearmedizin etabliertes funktionelles Schnittbildverfahren, das es erlaubt Informationen über biochemische und physiologische Prozesse in vivo zu erhalten. Die derzeit erreichbare räumliche Auflösung des Verfahrens beträgt etwa 5 mm für Hirnaufnahmen und etwa 8 mm für Ganzkörperaufnahmen, wobei erste verbesserte Bildrekonstruktionsverfahren eine Machbarkeit von 2 mm Auflösung in Zukunft möglich erscheinen lassen. Durch das geringe Signal/Rausch-Verhältnis des Messverfahrens, aber auch durch die Tatsache, dass der Stoffwechsel des Patienten über einen längeren Zeitraum betrachtet wird, betragen typische PET-Aufnahmezeiten mehrere Minuten bis Stunden. Dies hat zur Folge, dass Patientenbewegungen zunehmend die erreichbare räumliche Auflösung dieses Schnittbildverfahrens limitieren. Eine Immobilisierung des Patienten zur Reduzierung dieser Effekte ist hierbei nur bedingt hilfreich. Es kommt daher zu einer relevanten Auflösungsverschlechterung sowie zu einer Verfälschung der quantifizierten Stoffwechselparameter. Die vorliegende Arbeit beschreibt die Nutzbarmachung eines neuartigen Bewegungskorrekturverfahrens für klinische PET-Hirnaufnahmen. Mittels eines externen Bewegungsverfolgungssystems wird während einer PET-Untersuchung kontinuierlich die Kopfbewegung des Patienten registriert. Anhand dieser Bewegungsdaten führt ein neu entwickelter event-basierter Bewegungskorrekturalgorithmus eine räumliche Korrektur aller registrierten Koinzidenzereignisse aus und nutzt somit die als "List-Mode" bekannten Rohdaten eines PET Systems. Für die Akquisition dieser Daten wurden eigens Methoden entwickelt, die es erstmals erlauben, diese Rohdaten von einem ECAT Exact HR+ PET Scanner innerhalb eines akzeptablen Zeitraumes zu erhalten. Des Weiteren wurden Methoden für die klinische Akquisition der Bewegungsdaten sowie für die automatische Auswertung dieser Daten entwickelt. Ebenfalls Teil der Arbeit waren die Entwicklung von Methoden zur Integration in die klinische Routine (z.B. graphische Nutzeroberflächen). Nach der Entwicklung, Optimierung und Integration der event-basierten Bewegungskorrektur für die klinische Nutzung wurden Analysen anhand von Beispieldatensätzen vorgenommen. Es zeigten sich bei der Auswertung sowohl der qualitativen als auch der quantitativen Effekte deutliche Änderungen. In qualitativer Hinsicht wurden Bildartefakte eliminiert; bei der quantitativen Auswertung einer FDOPA Messung zeigte sich eine revelante Änderung der R0k3 Einstromraten eines irreversiblen Zweikompartment-Modells mit Referenzgewebe. Es konnte somit gezeigt werden, dass eine Integration einer Bewegungskorrektur unter Zuhilfenahme der Rohdaten eines PET Systems sowie unter Nutzung eines externen Verfolgungssystems nicht nur sinnvoll und in der klinischen Routine machbar ist, sondern auch zu maßgeblichen qualitativen und quantitativen Verbesserungen in der PET-Bildgebung beitragen kann.