Background and Rationale: Reproductive dysfunction affects more than 15% of Canadian women; however, the underlying causes remain largely unknown. Ultrasonography is the most commonly used research and diagnostic tool for imaging the ovaries and uterus. However, current ultrasonographic techniques allow the detection of ovarian structures (eg. follicles, corpora lutea) at diameters of only ≥2 mm. The increased effectiveness of synchrotron technology for imaging ovaries in comparison to conventional imaging methods is currently unknown. Overall Objective: The overall objective of this research was to determine the effectiveness of synchrotron techniques for imaging ovaries. We hypothesized that synchrotron techniques would provide greater contrast for visualizing structural details of follicles, corpora lutea (CL), and cumulus oocyte complexes (COC), compared to conventional ultrasonography. Materials and Methods: Three studies were conducted to evaluate phase-contrast based synchrotron imaging methods. The first study involved Diffraction Enhanced Imaging (DEI) of bovine ovaries (n=6). The second study involved Propagation-Based Computed Tomography (PB-CT) imaging of bovine (n=4) and human ovaries (n=4). A third, preliminary study was conducted to explore the use of Talbot Grating Interferometry (TGI-CT) imaging of bovine (n=1) and human ovaries (n=1). Fresh and formalin-fixed bovine and human ovaries were imaged without or with contrast injection into the ovarian artery. Following synchrotron imaging, all ovarian samples were evaluated using diagnostic ultrasonography and histology. Images obtained using synchrotron techniques, ultrasonography and histology were qualitative and quantitatively compared. Results: DEI allowed the identification of 71% of follicles ≥2 mm and 67% of CL detected using ultrasonography. Mean follicle diameter was similar between DEI (9.6 ± 2.4 mm), ultrasonography (9.0 ± 2.6 mm), and histology (6.9 ± 1.9 mm) for fresh ovaries without contrast (P = 0.70). Likewise, no difference in CL diameter was detected between DEI (11.64 ± 1.67 mm), ultrasonography (9.34 ± 0.35 mm), and histology (9.6 ± 0.4 mm), (P = 0.34). Antral Follicle Count (AFC; ≥2mm) was similar between ultrasonography (6.5 ± 0.7 mm, fresh with no contrast; 6.5 ± 2.5 mm, preserved with no contrast) and DEI ( 4.5 ± 0.5 mm, fresh with no contrast; 6.5 ± 0.50 mm, preserved with no contrast) (P > 0.05). However, the contrast resolution for differentiating follicles and CL was inferior with DEI compared to ultrasonography. Small antral follicles <2mm, cell layers comprising the follicle wall and COC were not detected using either DEI or ultrasonography. PB-CT imaging enabled the visualization of 100% of follicles ≥2 mm and 100% of CL that were detected with ultrasonography. CL containing a central cystic cavity were identified using PB-CT; however, CL without a central cystic cavity were not well-visualized. Mean follicle and luteal diameters did not differ among PB-CT, ultrasonography and histology (P>0.05). PB-CT was superior to ultrasonography for detecting small antral follicles <2 mm in bovine ovaries (P = 0.04), and the granulosa and theca cell layers of the follicle wall in bovine and human ovaries (P < 0.0001). However, TGI-CT images exhibited greater contrast resolution for visualizing small and large antral follicles, CL, and the cell layers of the follicle wall compared to both PB-CT and ultrasonography. High contrast structures resembling COC were detected with both PB-CT and TGI-CT, but not with ultrasonography. Only TGI-CT permitted the visualization of the oocyte within the COC in fresh and preserved ovaries. Conclusions: DEI was inferior to ultrasonography for detecting ovarian follicles and CL. PB-CT was superior to ultrasonography for visualizing follicles <2 mm, COC, and the cell layers of the follicle wall. However, PB-CT was as effective as ultrasonography for detecting and measuring follicles ≥2 mm and cystic CL. Preliminary findings suggest that TGI-CT provides the greatest contrast for imaging both ovarian macro- and microanatomy compared to PB-CT, DEI, and ultrasonography.

X-ray phase-contrast imaging has seen rapid development in recent decades due to its superior performance in imaging low-absorption objects, compared to traditional attenuation x-ray imaging. Having higher demand on coherence, x-ray phase-contrast imaging is performed mostly at synchrotrons. With the development of different imaging techniques, and the development of laboratory sources and x-ray optics, x-ray phase-contrast imaging can now be implemented on laboratory systems, which is promising and practical for broader range of applications. The subject of this thesis is the implementation, development and comparison of different laboratory phase-contrast methods using a liquid-metal-jet source. The three x-ray phase-contrast imaging methods included in this thesis are the propagation-, grating-, and speckle-based techniques. The grating-based method has been implemented on a laboratory system with a liquid-metal-jet source, which yields several times higher brightness than a standard solid-anode microfocus source. This allows shorter exposure time or a higher signal-to-noise ratio. The performance of the grating-based method has been experimentally and numerically compared with the propagation-based method, and the dose required to observe an object as a function of the object’s diameter has been investigated with simulations. The result indicates a lower dose requirement for the propagation-based method in this system but a potential advantage for the grating-based method to detect relatively large samples using a monochromatic beam. The speckle-based method, both the speckle-tracking and speckle-scanning techniques, has been implemented on a laboratory system for the first time, showing its adaptability to radiation of low temporal coherence. Tomography has been performed and shows the potential applications of this method on quantitative analysis on both absorption and phase information of materials. As a basis for further optimization and comparisons to other methods, the noise properties of the differential phase contrast of the speckle-based method have been studied and an analytical expression for the noise variance introduced, showing a similarity to the grating-based method. / Faskontrastavbildning med röntgenstrålning är en teknik som har utvecklats kraftigt de senaste årtiondena, eftersom den fungerar bättre än traditionella, absorptionsbaserade röntgenundersökningar för objekt med låg absorption. Den har dock höga krav på koherens, vilket gjort att den huvudsakligen används vid stora synkrotron-anläggningar. Tack vare utveckligen av nya avbildningstekniker, laboratoriekällor och röntgenoptik kan numera faskontrast användas även med laboratoriesystem, vilket är lovande då tekniken kan användas vid ett större antal olika tillämpningsområden Denna avhandling syftar till att tillämpa, utveckla och jämföra olika faskontrastmetoder i laboratoriemiljö, med en metallstråleröntgenkälla. De tre faskontrastmetoderna som behandlas i denna avhandling är propogation, gitter och speckelbaserad faskontrast. Den gitterbaserade metoden har implementerats i ett laboratoriesystem med en metallstrålekälla som ger flera gånger högre radians än en vanlig, fast mikrofokuskälla. Den högre radians en möjliggör kortare exponeringstider eller högre signal-brusförhållande. Den gitterbaserade tekniken har jämförts experimentellt och numeriskt med den propageringsbaserade metoden. Den strålningsdos som krävs för observera ett objekt, som funktion av dess diameter, har jämförts för de båda teknikerna, den här gången via simuleringar. Resultaten visar på en lägre strålningsdos för den propagationsbaserade tekniken i detta fall, men även att det finns en potentiell fördel för den gitterbaserade tekniken för något större objekt med monokromatisk röntgenstrålning. Speckelbaserade tekniker, nämare bestämt den som bygger på att spåra speckel och den som bygger på att scanna diffusorn, har för första gången implementerats i laboratoriemiljö. Därmed har visats att de fungerar även för strålning med låg tidskoherens. Tekniken har även använts för tomografi och visar möjliga tillämpningar inom kvantitativ analys av material. För att förenkla framtida optimeringar och jämförelser av tekniken med andra metoder, har brusegenskaperna för den speckelbaserade metoden studerats och visat sig likna den gitterbaserade metoden. / <p>QC 20160921</p>

Phase-contrast imaging (PCI) is a modality of medical x-ray imaging that can solve one of the main limitations with conventional attenuation-based imaging: the imaging of materials with low attenuation coefficients, such as soft tissues. A modality of PCI, Propagation-based phase-contrast imaging (PBI), was used in this project. This method does not require any optical elements than those used in the conventional imaging; it does, however, require more processing compared to other kinds of PCI. In addition to the reduced image quality, the required image reconstruction process, with PCI, also requires several manual adjustments, which in turn results in a lot of time consuming. In order to achieve that, a simple iterative image reconstruction method that combines Simultaneous Iterative Reconstruction Technique (SIRT) and propagation-based phase-contrast imaging was developed. The proposed method was compared with another commonly used phase-retrieval method, Paganin's algorithm. The obtained results showed higher resolution and reduced blur artefacts compared with Paganin's method. The developed method also appeared to be less sensitive to error in the input parameters, such as the attenuation coefficient, but also more time-consumption than the non-iterative Paganin's method, due to the higher data processing. / Faskontrastavbildning är en ny medicinsk röntgenavbildningsteknik, som har utvecklats för att ge bättre kontrast än konventionell röntgenavbildning, särskilt för objekt med låg attenuationskoefficient, såsom mjuk vävnad. I detta projekt användes s.k. propagationsbaserad faskonstrantavbildning, som är en av de enkla metoder som möjliggör faskontrastavbildningen, utan extra optiska element än det som ingår i en konventionell avbildning. Metoden kräver dock mer avancerad bildbehandling. Två av de huvudsakliga problemen som oftast uppstår vid faskontrastavbildning är minskad bildkvalité efter den väsentliga bildrekonstruktionen, samt att den är tidskrävande p.g.a. manuella justeringar som måste göras. I det här projektet implementerades en enkel metod baserad på en kombination av den iterativa algoritmen för bildrekonstruktion, Simultaneous Iterative Reconstruction Technique (SIRT), med propagationsbaserad faskonstrantavbildning. Resultaten jämfördes med en annan fasåterhämtningsmetod, som är välkänd och ofta används inom detta område, Paganinsmetod. Efter jämförelsen konstaterades att upplösningen blev högre och artefakter som suddighet reducerades. Det noterades också att den utvecklade metoden var mindre känslig för manuell inmatning av parametern för attenuationskoefficient. Metoden visade sig dock vara mer tidskrävande än Paganin-metoden.