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The School of Technology and Health, STH, has been developing a micro-CTscanner for pre-clinical imaging. The scanner consists of an X-ray tube and aflat panel sensor fixated on a gantry rotating around the object to be imaged. Acomputer located on the gantry runs an acquisition software for communicationbetween the devices on the gantry as well as for controlling them. For this thesisthe acquisition software has been significantly improved in terms of functionality,performance, usability and user-adaptivity.Projection images acquired by the microCT are created by measuring theX-ray beam attenuation as a function of spatial location. Using all projectionimages, a 3-dimensional image can be reconstructed giving a map of the attenuationinside the object, thus providing information about its internal structure.A common artifact for CT-scanner images is the cupping arti fact which the attenuation in the middle of an object is underestimated due to beam hardening.For the second part of this thesis, a method for correcting for this artifact hasbeen implemented and tested. The cupping artifact was successfully removedin most cases, although it was shown that for some situation it is not applicable

Several BWR utilities are adopting practices for determining the state of control rods based on the neutron sensitive LPRM and gamma sensitive TIP measurement systems of the nuclear reactor core. This method is in this study evaluated by quantitatively analyzing the detector sensitivity to several material and geometrical distortions in the detector vicinity, using the Los Alamos National Laboratory stochastic Monte Carlo code MCNP5 and the Westinghouse 3D core simulator POLCA7. These results are used to determine whether or not there are potential pitfalls that need to be considered when applying the in-core detector based diagnostic methods to determine the state of control rods. This study also addresses the utility concern about shutdown margin deterioration due to potential loss of neutron absorbing material from control rods. It is found that indication of potential control rod leakage by means of the LPRM and the gamma TIP probe detector systems is feasible, provided that both detector systems show similar deviations that correspond to the potential loss of neutron absorbing material from the control rod. Furthermore, it is possible to correlate the observed detector signaldeviation to the magnitude of the distortion. The study lays out criteria that need to befulfilled for indication of control rod leakage to be reasonable, but it is to be noted that nodefinitive stand is or can be taken regarding the state of individual control rods at anyutility. The shutdown margin is found not to be significantly deteriorated in any of the utility cases that are studied under an assumption of control rod loss of neutron absorbing material as apotential cause for anomalous detector readings. In order to provoke a significant effect, asection of the top fifth of the control rod must have lost neutron absorbing material next to a control rod position with already low shutdown margin.

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Proton radiation therapy allows for delivering a high dose to a well-confinedregion of interest due to the characteristic proton dose deposition. Due to protonrange straggling, anatomic variations in patients and small patient setup errors,treatment plans needs to account for proton range uncertainties of up to 3.5% invivo.Therefore, it is highly desirable to measure the proton range on-line in orderto minimize margins in the treatment plan. Initially, the feasibility of on-linerange monitoring through prompt gamma imaging and Positron EmissionTomography (PET) at different proton energies is evaluated using GEANT4Application for Tomographic Emission (GATE) Monte Carlo (MC) simulations.In the second phase, the performance of a lead knife-edge slit system for promptgamma imaging was evaluated with MC simulations. Results from simulationsindicate that prompt gamma emission and PET isotope production is correlatedwith proton range, with discrete prompt gamma emission lines from Carbon (4.4MeV) showing good correlation. The evaluated system was able to image thepeak gamma emission location at three different slit positions with promisingprecision ± 1 mm, ± 0.7 mm and ± 1.3 mm, and average shifts of -2 mm, -3 mmand -4 mm, respectively. The proton range was resolved with mean profile shiftsof -12 ± 1 mm, -13 ± 0.7 mm and -14 ± 1.3 mm, following prompt gamma crosssectionbehavior with peak emission- and threshold energies. The results providean indication of the potential of the knife-edge slit system and future work willinclude more extensive MC simulations and experimental measurements at the Skandion clinic to determine its clinical validity. / Strålbehandling av cancer med hjälp av protoner är fördelaktigt jämfört medkonventionell strålterapi då protonerna kan leverera en hög dos till ett välavgränsat område samtidigt som dosen till intilliggande vävnad effektivtreduceras. Tack vare statistiska variationer i protoners dosfördelning, anatomiskaavvikelser i patienter samt små fel vid patientfixering måste behandlingsplanerinnehålla marginaler som motsvarar ca 3.5% avvikelse i protonräckvidd. Att irealtid kunna mäta protoners räckvidd i patienten skulle vara tills stor nytta ochskulle bidra till att minska marginalerna i behandlingsplanen. I ett första skede avarbetet undersöktes möjligheten att avbilda protonräckvidden med promptgammaemission och Positron Emissions Tomografi (PET) genom GEANT4Application for Tomographic Emission (GATE) Monte Carlo (MC) simuleringar.Resultatet från MC simuleringarna användes sedan för att utvärdera ettdetektorsystem för prompt-gamma avbildning. Simuleringarna indikerade attproduktion av både prompt-gamma och PET isotoper är korrelerade medprotonernas räckvidd, särskilt 4.4 MeV emissionslinjen från Kol. Positionen förmaximal gamma emission kunde avbildas för tre olika positioner idetektorsystemet med en medelförskjutning på -2 ± 1 mm, -3 ± 0.7 mm och -4 ±1.3 mm. Detektorprofilen var förskjuten -12 ± 1 mm, -13 ± 0.7 mm och -14 ± 1.3mm jämfört med protonräckvidden p.g.a. interaktionernas energiberoende.Resultatet påvisar detektorsystemets potential att avbilda prompt-gamma fotoneroch framtida arbete omfattar ytterligare MC simuleringar och experimentellamätningar på Skandionklinken.

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