Objectives: There is increasing research regarding pathology of the maxillary sinus in dentistry. This may be attributed to the increasing routine use of cone beam computerized tomography (CBCT) for diagnosis and treatment planning of complex dental treatments, and incidental findings identified by clinicians during the process. This study aims to compare two different CBCT viewing software programs, and evaluate their detection of pathological findings in the maxillary sinus of a group of patients at Temple University School of Dentistry. Methods: A total of 316 CBCT scans taken on 176 females and 140 males (202 Caucasian, 69 African-American, 30 Asian, and 15 Hispanic) between 2009 and mid- 2013 by the Division of Oral & Maxillofacial Radiology at Temple University School of Dentistry were evaluated using i-CAT and INFINITT viewing software programs. The CBCT scans were examined with both viewing programs, and classified each time by independent evaluators as yielding one of 5 categories of maxillary sinus pathology as follows: healthy status with mucosal thickening ≤ 3 millimeters, mucosal thickening > 3 millimeters, polypoidal mucosal thickening, partial opacification, or complete opacification. Results: The i-CAT viewing program revealed 193 (61.1%) scans with a healthy maxillary sinus presenting with mucosal thickening ≤ 3 millimeters, and 123 (38.9%) scans yielding various forms of maxillary sinus pathology. In comparison, the INFINITT viewing program found 194 (61.4%) scans with healthy maxillary sinus conditions without pathology, and 122 (38.6%) scans with various types of maxillary sinus pathology. The difference in detection of maxillary sinus pathology between the i-CAT and INFINITT viewing programs was not statistically significant. Conclusions: The i-CAT and INFINITT viewing software programs for evaluation of human CBCT scans used in dental treatment planning provided nearly identical information relative to detection of maxillary sinus pathology. This suggests that both viewing programs may be employed interchangeably by clinicians in their pre- treatment evaluation of the maxillary sinus in dental patients. / Oral Biology

Bakgrund: Cone beam computed tomography (CBCT) är en form av datortomografi vanlig inom odontologi och börjar utnyttjas mer inom ortopedisk diagnostik. Frakturer i övre extremiteter är vanligt förekommande i samband med trauma. Konventionell röntgen är oftast förstahandsmetod men kan inte alltid utesluta scaphoideumfraktur, som obehandlad kan ge allvarliga konsekvenser. Syfte: Syftet är att utvärdera CBCT som metod vid fraktur i övre extremiteter genom att jämföra med andra modaliteter. Metod: Arbetet är en systematisk litteraturstudie. Databaserna Medline, CINAHL och PubMed användes. Endast artiklar publicerade inom de senaste 10 åren inkluderades. Kvalitetsgranskning utfördes med protokoll från Hälsohögskolan i Jönköping. Resultat: 15 artiklar inkluderades i resultatet. Faktorer som identifierades var konkordans, stråldos, bildkvalitet, diagnostisk kvalitet samt patienttolerans och undersökningstid. CBCT hade överlägsen eller likvärdig konkordans. I åtta av nio artiklar visades CBCT ha lägre stråldos än jämförande modalitet. Generellt var bildkvaliteten god för CBCT. Skilda resultat uppkom för diagnostisk förmåga. Patienttoleransen var högre för CBCT än multidetektor-CT (MDCT) gällande tid. Slutsats: CBCT påvisade god bildkvalitet och diagnostisk förmåga till en relativt låg stråldos, samt högre sensitivitet och specificitet än konventionell röntgen. På grund av skillnader i mätinstrument i det insamlade materialet kan ingen definitiv slutsats dras. Vidare studier inom ämnet rekommenderas. / Background: Cone beam computed tomography (CBCT) is a method commonly used in odontology and is becoming more used in orthopedic diagnostics. Fractures in upper extremities are a common occurrence in trauma. Conventional radiography is often the firsthand method but cannot always exclude scaphoid fractures, which untreated can have serious consequences. Purpose: The purpose is to evaluate CBCT as an examination method for fractures in the upper extremities by comparing with other modalities. Method: This study is a systematic literature review. The databases used were Medline, CINAHL and PubMed. Only articles published within the last 10 years were included. A quality audit was implemented using a protocol from Jönköping University. Results: 15 articles were included. The factors identified were observer agreement, radiation dose, image quality, diagnostic quality, patient tolerance and image duration. CBCT had a better or equal observer agreement. In eight out of nine articles, CBCT was shown to have a lower radiation dose than its comparative modality. In general, a good image quality in CBCT was found. Differing results were found about diagnostic ability. The patient tolerance was higher for CBCT than multidetector-CT (MDCT) regarding image duration. Conclusions: CBCT demonstrated a good image quality and diagnostic ability to a relatively low radiation dose, and a higher sensitivity and specificity than conventional radiography. Due to differences in measuring instruments used in the gathered material, no definitive conclusion could be drawn. Further studies in the subject is recommended.

L'un des objectifs de l'optimisation de la planification du traitement du cancer de la prostate en radiothérapie est de maintenir les marges ajoutées au volume cible clinique (CTV) aussi réduites que possible pour diminuer les volumes de tissus normaux irradiés. Plusieurs méthodes ont été proposées pour définir ces marges : 1) Les méthodes basées sur l’observation des mouvements obtenue par différents systèmes d’imagerie, 2) Des méthodes prédictives des mouvements des organes: à partir d’un modèle représentant les mouvements des organes pelviens, un calcul d’une marge personnalisée peut être réalisé. Nous avons ainsi développé et optimisé un modèle biomécanique par éléments finis de la prostate, de la vessie et du rectum. Ce modèle décrit le mouvement et la déformation des organes pelviens lors du remplissage de certains organes comme la vessie et le rectum. Une évaluation de ce modèle permettant de prédire les mouvements de la prostate au cours des différentes séances de radiothérapie, est montrée en utilisant une série d’images CBCT (Cone Beam Computerized Tomography) / One of the goals of optimizing treatment planning of prostate cancer radiation therapy is to maintain the margins added to the clinical target volume (CTV) as small as possible to reduce the volumes of normal tissue irradiated. Several methods have been proposed to define these margins: 1) Methods based on the observation of movements obtained by different imaging systems, 2) The predictive methods of the movement of organs, from a model representing the motions of pelvis organs, a calculation of a margin can be made. We have developed and optimized a finite element biomechanical model of the prostate, bladder and rectum. This model describes the movement and deformation of the pelvic organs during the filling of certain organs such as the bladder and rectum. An evaluation of this model to predict the movement of the prostate during the various sessions of radiotherapy is shown using a series of CBCT images (Cone Beam Computerized Tomography)

Cone Beam Computed Tomography (CBCT) är en relativt ny modalitet att användas inom ortopedin till olika typer av skador och användningen håller på att öka. Författarna till denna studien har under skolgången endast i liten omfattning stött på denna modalitet, vilket gjorde att deras intresse för att lära sig mer om den var stort. Syftet med den här studien var att sammanställa vilka fördelar och nackdelar modaliteten har vid frakturutredning i extremiteter. Metoden som användes till den här studien var en allmän litteraturstudie, där fakta samlades in från artiklar i olika databaser och även i kurslitteratur. Kvalitetsgranskningen gjordes av båda författarna enligt ett kvalitetsgranskningsprotokoll som var specialutformat för att passa studien bra.  I analysen sammanställdes informationen från artiklarna och kategoriserades för att göra resultatet mer lättöverskådligt. Resultatet visade på att fler frakturer hittas med hjälp av CBCT:n än vad det görs med konventionell röntgen. Detta gällde särskilt scaphoideum-, karpalbens-, och handledsfrakturer. Den visade sig även vara ett hjälpmedel gällande bedömning av instabil eller stabil fotled efter en viss typ av fotledsfraktur. Magnetisk resonans (MR) visade sig var något bättre än CBCT:n på att detektera scaphoideumfrakturer. Frakturdetekteringsförmågan hos CBCT:n var likvärdig som med den hos Multi Detector Computed Tompography (MDCT). Stråldosen ifrån CBCT:n visade sig vara högre än vid konventionell röntgen, men mindre än stråldosen från MDCT:n. CBCT:n var även billigare att köpa in och underhålla än MDCT:n. CBCT:n visade sig ha en vanlig typ av artefakter, som var beam-hardening artefakter och rörelseartefakter. Författarna till denna studien tror att CBCT:n kan vara ett bra komplement till konventionell röntgen vid olika frakturer i extremiteter, men mer forskning behöver göras då området fortfarande är relativt nytt och informationen är begränsad. / Cone Beam Computed Tomography (CBCT) is a relatively new modality to be used in orthopedic for various types of injuries and the usage is increasing. The authors of this study have only encountered this modality a little bit during school, which meant that their interest in learning more about it was big. The purpose of this study was to compile the advantages and disadvantages of this modality in fracture examination in extremities. The method used for this study was a general literature study, where facts were collected from articles in different databases and also in literature. The quality review was done by both authors according to a quality audit protocol that was tailor-made to suit the study well.  In the analysis, the information was compiled from the articles and categorized to make the result more easy to understand. The result showed that more fractures were found using CBCT than conventional X-ray. This was especially true of scaphoidum, carpal, and wrist fractures. It also proved to be an aid in assessing unstable or stable ankle after a certain type of ankle fracture. Magnetic resonance (MR) proved slightly better than the CBCT to detect scaphoid fractures. The fracture detection capability of the CBCT was similar to that of Multi Detector Computed Tompography (MDCT). The radiation dose from the CBCT was found to be higher than in conventional X-rays, but less than the radiation dose from the MDCT. The CBCT was also cheaper to buy and maintain than the MDCT. The CBCT proved to have a common type of artifacts, such as beam-hardening artifacts and movement artifacts. The authors of this study believe that the CBCT may be a good complement to conventional x-ray in various fractures in extremities, but more research needs to be done as this area is still relatively new and the information is limited.

Les variations affectant les dimensions et la forme de l’os hyoïde sont analysées chez le vivant à partir de tomodensitométries volumétriques en faisceau conique (CBCT) et complétées par des téléradiographies. Ces variations sont mises en relation avec différents paramètres biologiques (âge, sexe, population). La documentation regroupe 94 enfants et 83 adultes issus de 2 échantillons de populations, Française et Vietnamienne. Pour la première fois, l’existence d’une croissance différentielle de l’os hyoïde entre filles et garçons est mise en évidence, en termes d'amplitude et de chronologie des modifications osseuses. Chez l’adulte, la fusion des grandes cornes au corps de l'os hyoïde intervient dans l’évolution des dimensions de l'os mais ce processus biologique ne présente aucune loi prédictive. Aucune différence significative de l'âge de cette fusion n’est observée entre hommes et femmes et les facteurs l’influençant restent inconnus. Des variations affectant les dimensions et la forme de l'os hyoïde entre populations sont identifiées. La classification de la morphologie de l'os hyoïde selon 6 catégories qui est proposée consitue un outil pour l’étude des séries archéologiques. Des corrélations significatives entre les dimensions de l'os hyoïde et les voies aériennes supérieures sont observées, confirmant leurs relations étroites et réciproques, tant anatomique que fonctionnelle. Tous ces paramètres, évalués dans différents types faciaux, montrent en revanche des manifestations plus complexes qui nécessitent plus de recherche pour affiner les résultats. / In this study, variations of size, shape and position of the hyoid bone are analyzed with different biological parameters (age, sex, population) from Cone Beam CT and reconstitued radiographs of living people. The study sample includes 94 children and 83 adults from two populations French and Vietnamese. The results bring the first evidence of a differential growth of the hyoid bone between girls and boys in terms of magnitude and timing of bone changes. In adults, the fusion of the greater cornua with the hyoid body is involved in the dimensional changes of the bone but no significant influencing factor (like sex or population) for this biological process can be confirmed. Variations of dimension and shape of the hyoid bone between populations are identified. Within the study, a new morphological classification of the hyoid bone based on metric data is proposed. This classification distinguishes 6 categories of shape and constitutes a tool for studies of archaeological series. Significant correlations between dimensions and position of the hyoid bone and upper airways is observed, thus confirming their close mutual relationships, both anatomical and functional. All these parameters, analyzed in different facial types, show, however, a complex interaction that requires more research to refine the results.

The topic of this thesis is the design of dental X-ray. User problems were identified based on the design and technical analysis for which solutions are presented in the work. The innovative shape and design solution shows a new approach to dental X-rays. The main benefit of the design is the solution to real ergonomic problems that can occur during the interaction of the operator or patient and the device. The design corresponds to current trends in the evolving design field of medical design.

La tomographie à faisceau conique (CBCT) est devenue la modalité de référence pour les praticiens du domaine dentaire. Sa relative nouveauté et ses spécificités impliquent que le domaine du traitement de ces images est peu développé à l’heure actuelle. En partenariat industriel avec Carestream Dental, le premier volet de la thèse a conduit à développer une méthode de segmentation semi-automatique de chaque dent, reposant sur l’utilisation de contraintes de forme et d’intensité, et formulée comme un problème de minimisation d’énergie résolu par coupure de graphe. Les résultats montrent une bonne qualité de segmentation avec un coefficient de Dice moyen de 0, 958. Une application logicielle a été réalisée pour la mise en œuvre de la méthode de segmentation auprès des praticiens, en tenant compte des contraintes techniques et temporelles imposées par le contexte clinique, ainsi que du profil des utilisateurs. Un travail préliminaire d’extension de l’approche par coupure de graphe pour segmenter simultanément plusieurs dents à été réalisé, montrant la nécessité de rendre les contraintes de formes plus adaptées aux images et de modifier la méthode d’optimisation pour atteindre des temps de calcul compatibles avec la pratique clinique. Un second volet prospectif des travaux concerne la constitution d’un modèle structurel de la région maxillo-faciale pour formaliser les connaissances a priori sur les organes et leurs interactions. Ce modèle est un graphe conceptuel où sont représentés les concepts des structures et des relations. En particulier, les relations d’alignement et “le long de” ont été modélisées en 3D dans le cadre des ensembles flous. / Cone-Beam computed tomography (CBCT) is the new standard imaging method for dental practitioners. The image processing field of CBCT data is still underdeveloped due to the novelty of the method and its specificities compared to traditional CT. With Carestream Dental as industrial partner, the first part of this work is a new semi-automatic segmentation protocol for teeth, based on shape and intensity constraints, through a graph-cut optimization of an energy formulation. Results show a good quality of segmentation with an average Dice coefficient of 0.958. A fully functional implementation of the algorithm has led to a software available for dentists, taking into account the clinical context leading to temporal and technical difficulties. A preliminary extension to multi-objects segmentation showed the necessity to get more stringent shape constraints as well as a better optimization algorithm to get acceptable computation times. The second part of this thesis, more prospective, is about the creation of a structural model of the maxillo-facial space, to formalize the a priori knowledge on organs and theirs spatial relations. This model is a conceptual graph where structures and relationships are seen as concepts. In particular, the spatial relations “Along” and “Aligned”, modeled in a fuzzy set framework, have been extended to 3D objects.

Excessive imaging doses from repeated scans and poor image quality mainly due to scatter contamination are the two bottlenecks of cone-beam CT (CBCT) imaging. This study investigates a method that combines measurement-based scatter correction and a compressed sensing (CS)-based iterative reconstruction algorithm to generate scatter-free images from low-dose data. Scatter distribution is estimated by interpolating/extrapolating measured scatter samples inside blocked areas. CS-based iterative reconstruction is finally carried out on the under-sampled data to obtain scatter-free and low-dose CBCT images. In the tabletop phantom studies, with only 25% dose of a conventional CBCT scan, our method reduces the overall CT number error from over 220 HU to less than 25 HU, and increases the image contrast by a factor of 2.1 in the selected ROIs. Dual-energy CT (DECT) is another important application of CBCT. DECT shows promise in differentiating materials that are indistinguishable in single-energy CT and facilitates accurate diagnosis. A general problem of DECT is that decomposition is sensitive to noise in the two sets of projection data, resulting in severely degraded qualities of decomposed images. The first study of DECT is focused on the linear decomposition method. In this study, a combined method of iterative reconstruction and decomposition is proposed. The noise on the two initial CT images from separate scans becomes well correlated, which avoids noise accumulation during the decomposition process. To fully explore the benefits of DECT on beam-hardening correction and to reduce the computation cost, the second study is focused on an iterative decomposition method with a non-linear decomposition model for noise suppression in DECT. Phantom results show that our methods achieve superior performance on DECT imaging, with respect to noise reduction and spatial resolution.

BACKGROUND: Clinicians rely on radiographs and clinical exam to assess infrabony defects. However, two-dimensional radiographs have many limitations. Three-dimensional imaging has shown promise and has provided more precise measurements of defects created in skulls. The aim of this study is to compare the diagnostic efficacy of cone beam computed tomography to clinical measurements in patients presenting with infrabony defects. METHODS: The study population included 20 patients with 25 infrabony defects. Clinical measurements of pocket depth (PD), gingival margin (GM), bone sounding (BS) were obtained and PD and BS were compared to CBCT measurements. RESULTS: The average difference between the means of measurements obtained by BS and by CBCT was 1.08mm with BS always being the greater value. BS measurement was statistically significantly different with p<0.05 from CAL and CBCT values. CONCLUSION: The CBCT provided measurements that are on average 1.08mm smaller than bone sounding measurements.

Accounting for respiration motion during imaging helps improve targeting precision in radiation therapy. Respiratory motion can be a major source of error in determining the position of thoracic and upper abdominal tumor targets during radiotherapy. Thus, extracting respiratory motion is a key task in radiation therapy planning. Respiration-correlated or four-dimensional CT (4DCT) imaging techniques have been recently integrated into imaging systems for verifying tumor position during treatment and managing respiration-induced tissue motion. The quality of the 4D reconstructed volumes is highly affected by the respiratory signal extracted and the phase sorting method used. This thesis is divided into two parts. In the first part, two image-based respiratory signal extraction methods are proposed and evaluated. Those methods are able to extract the respiratory signals from CBCT images without using external sources, implanted markers or even dependence on any structure in the images such as the diaphragm. The first method, called Local Intensity Feature Tracking (LIFT), extracts the respiratory signal depending on feature points extracted and tracked through the sequence of projections. The second method, called Intensity Flow Dimensionality Reduction (IFDR), detects the respiration signal by computing the optical flow motion of every pixel in each pair of adjacent projections. Then, the motion variance in the optical flow dataset is extracted using linear and non-linear dimensionality reduction techniques to represent a respiratory signal. Experiments conducted on clinical datasets showed that the respiratory signal was successfully extracted using both proposed methods and it correlates well with standard respiratory signals such as diaphragm position and the internal markers’ signal. In the second part of this thesis, 4D-CBCT reconstruction based on different phase sorting techniques is studied. The quality of the 4D reconstructed images is evaluated and compared for different phase sorting methods such as internal markers, external markers and image-based methods (LIFT and IFDR). Also, a method for generating additional projections to be used in 4D-CBCT reconstruction is proposed to reduce the artifacts that result when reconstructing from an insufficient number of projections. Experimental results showed that the feasibility of the proposed method in recovering the edges and reducing the streak artifacts.