Accurate, practical, and affordable pose tracking on manually operated C-arm fluoroscopes is a major technical challenge. Conventional tracking methods, such as optical cameras and radiographic fiducials, are hampered by significant shortcomings. Optical cameras are delicate, costly, and have a complex system setup that is easily susceptible to camera obstruction in cluttered operating room. Radiographic fiducials occupy a significant portion of the fluoroscopic imaging space. Using fiducials also requires segmentation that limits clinical use. In this thesis, an alternative form of tracking is proposed to encode the rotational joints of manually operated C-arms using a tilt sensing accelerometer for tracking the C-arm rotational pose. The technique is evaluated by affixing an accelerometer to a full-scale C-arm where a webcam is used as a substitute for X-ray imaging. Ground truth C-arm rotational poses were obtained from the webcam by tracking a checkerboard plate. From these rotational poses, a series of angle and structural correction equations were formulated that can properly relate the accelerometer angle readings to the C-arm rotational pose in real-time and compensate for systematic structural C-arm deformations, such as sagging and bending. Real-time rotational pose tracking of the primary and secondary joint rotations of the C-arm showed an accuracy of 0.5 degrees in the entire range of interest. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2011-01-28 12:07:32.781

Nephrolithiasis can be a painful problem due to presence of kidney stones. Kidney stone is among the common painful disorders of the urinary system. Various imaging modalities are used to diagnose patients with symptoms of renal or urinary tract disease such as plain kidney, ureter, bladder x-ray (KUB), intravenous pyelography (IVP), and computed tomography (CT). As a traditional three-dimensional (3D) nephrolithiasis and kidney stones detection technique, computed tomography (CT) provides detailed cross-sectional images as well as 3D structure of kidney from moving the x-ray beam in a circle around the body. However, the risk of CT scans of the kidney is relatively higher exposure to radiation which is more than regular x-rays. C-arm technique is a new x-ray imaging modality that uses 2D array detector and cone shaped x-ray beam to create 3D information about the scanned object. Both x-ray source and 2D array detector cells mounted on C-shaped wheeled structure (C-arm). A series of projection images are acquired by rotating the C-arm around the patient in along circular path with a single rotation. The characteristic structure of C-arm allows to provide wide variety of movements around the patient that helps to remain the patient stationary during scanning time. In this work, we investigated a C-arm technique to generate a series of tomographic images for nephrolithiasis and detection of kidney stones. C-arm tomographic technique (C-arm tomosynthesis) as a new three dimensional (3D) kidney imaging method that provides a series of two dimensional (2D) images along partial circular orbit over limited view angle. Our experiments were done with kidney phantom which formed from a pig kidney with two embedded kidney stones inside it and low radiation dosage. Radiation dose and scanning time needed for kidney imaging are all dramatically reduced due to the cone beam geometry and also to limitation of angular rotation. To demonstrate the capability of our C-arm tomosynthesis to generate 3D kidney information for kidney stone detection, two groups of tomographic image reconstruction algorithms were developed for C-arm tomosynthesis: direct algorithms such as filtered back projection (FBP) and iterative algorithms such as simultaneous algebraic reconstruction technique (SART), maximum likelihood expectation maximization (MLEM), ordered- subset maximum likelihood expectation maximization (OS-MLEM) and Pre-computed penalized likelihood reconstruction (PPL). Three reconstruction methods were investigated including: pixel-driven method (PDM), ray-driven method (RDM) and distance driven method (DDM). Each method differs in their efficiency of calculation accuracy per computing time. Preliminary results demonstrated the capability of proposed technique to generate volumetric data about the kidney for nephrolithiasis and kidney stone detection by using all investigated reconstruction algorithms. In spite of each algorithms differs in their strategies, embedded kidney stone can be clearly visualized in all reconstruction results. Computer simulation studies were also done on simulated phantom to evaluate the results for each reconstruction algorithm. To mimic kidney phantom, simulated phantom was simulated with two different size kidney stones. Dataset of projection images was collated by using a virtual C-arm tomosynthesis with geometric configuration similar to real technique. All investigated algorithms were used to reconstruct 3D information. Different of image quality functions were applied to evaluate the imaging system and the reconstruction algorithms. The results show the capability of C-arm tomosynthesis to generate 3D information of kidney structures and to identify the size and location of kidney stones with limited amount of radiation dose.

Målet med projektet var att undersöka ifall Siemens ARTIS Pheno hade fördelar jämfört med likvärdig utrustning såsom G-båge och C-arm och undersöka om ARTIS Pheno kan tillämpas inom andra områden än enbart rygg-, bäcken-och neurokirurgi. Resultatet ifrån rapporten visar att ARTIS Pheno kan med fördel användas inom andra områden, såsom traumaortopedi. Metoden för projektet var litteraturstudier, en intervju och undersökningar kring ARTIS Pheno, G-båge och C-arm. Litteraturstudiernas innehåll samt resultat sammanställdes i tabeller. På grund av bristen på artiklar kring ARTIS Pheno vidgades sökningarna till artiklar med liknande utrustning. En jämförelse mellan ARTIS Pheno, G-båge och C-arm gjordes för att se vilka för-och nackdelar ARTIS Pheno hade gentemot de andra och en praktisk mätning av ARTIS Pheno utfördes på Karolinska Universitets Sjukhuset Huddinge. Resultatet visade att majoriteten av artiklarna, 70%, talade för att användandet av en mer avancerad röntgenutrustning, ARTISPheno, inom traumaortopedi. Jämförelsen mellan ARTIS Pheno, G-båge och C-arm visade att ARTIS Pheno är dyrare men har mer fördelar och är bättre rustad än både G-bågen och C-armen. Mätningarna med ARTIS Pheno visar tydligt att det blir en bättre och tydligare bild på frakturen som kommer att hjälpa kirurgen i att utföra ett korrektare och säkrare ingrepp. Slutsatsen är att användandet av ARTIS Pheno vid traumaortopedi, kommer att hjälpa kirurgen att utföra ett mer korrekt och säkrare ingrepp vid komplexa frakturer. Vid Karolinska Universitetssjukhuset Huddinge skulle en installation och nyttjandet av ARTIS Pheno vid traumaortopedi medföra fördelar dock, vid en mindre vårdinrättning skulle det inte vara ekonomiskt hållbart. / The aim of the project was to investigate whether ARTIS Pheno had benefits compared with equivalent equipment such as the G-arch and C-arm and to investigate whether ARTIS Pheno can be applied in other fields of surgery than spinal-, pelvic-and neurosurgery. The results of the report showed that ARTIS Pheno can be used in other areas, such as trauma orthopedics. The method for the project was literaturestudies, an interview and to review ARTIS Pheno, G-arch and C-arm. The content and the results from the literature studies were compiledin charts. Due to the lack of articles regarding ARTIS Pheno the search was enlarged to articles with comparable devices. A comparison between ARTIS Pheno, G-arch and C-arm was created to see the pros and cons of ARTIS  Pheno compared to the other equipment. A practical measurement of ARTIS Pheno was performed at Karolinska University Hospital Huddinge. The results of the articles showed that the majority, 70%, favored a more advanced X-ray equipment, ARTIS Pheno, in trauma orthopedics. The comparison between ARTIS Pheno, G-arch and C-arm showed that ARTIS Pheno is more expensive but has more advantages and is better equipped for complex fractures, compared to both the G-arch and the C-arm. Measurements with ARTIS Pheno clearly show that there will be a better and clearer picture of fractures which will help the surgeon to carry out a more correct and safe operation. The conclusion is that using ARTIS Pheno in trauma orthopedics, will help the surgeon to perform a more accurate and safe procedure in complex fractures. To install and use ARTIS Pheno within trauma orthopedics at Karolinska University Hospital, would induce benefits, however, it would not be economically sustainable in smaller healthcare facilities.

No description available.

No description available.

The subject of this diploma thesis is design of X-ray apparatus for medical intention – an angiographic set which consists of a C-Arm and an angiographic table. The elaboration deals particularly with an attractive organic design, that is aimed to have a positive psychological effect, and with an innovation in construction of apparatus in order to be as various-purpose as possible, to conform to the most exacting requirements and procedures, and to advance diagnostic possibilities in the given category. In the thesis diagnostic procedures, which along with technical and ergonomical factors influence the shape and also the total set conception, are considered. This thesis does not contain a separate display system which is not a part of project.

Continuous improvement of image quality is one of the priorities in medical imaging. Therefore, development of a simulation tool allowing to generate realistic images would be of great value to understand better the impact of the components on the image quality metrics and to choose imaging set-ups or new design features to optimize output of existing systems and to prototype new ones and to formalize the link between objective and subjective image quality metrics. Therefore, the purpose of this project, was to contribute to adaptation and validation of an existing simulator for simulation of C-arm X-ray imaging. Firstly, the study of the existing simulation tool was performed to choose further development axes. Afterwards, preliminary estimations of simulation complexity by evaluating the number of photons for a given imaging examination were performed. Previous studies[1] showed the determining impact of focal spot on imaging performance (reducing the limiting spatial frequency in common examination conditions) of X-ray interventional imaging systems.  Therefore, the work focused on the improvements of source model, in particular realistic focal spot was defined and simulations of images with close-to-real sharpness were performed and compared to experimentally acquired images. Finally, a part of this project was dedicated to scatter study. An experimental set-up and "scatter map" analysis were designed to determine the scatter evolution as function of imaging field-of-view.  First simulations were also performed. [1] Samei, E., Ranger, N., MacKenzie, A., Honey, I., Dobbins, J. and Ravin, C. (2008). Detector or System? Extending the Concept of Detective Quantum Efficiency to Characterize the Performance of Digital Radiographic Imaging Systems 1. Radiology, 249(3), pp.926-937.

We propose an exact filtered backprojection algorithm for inversion of the cone beam data in the case when the trajectory is composed of a distorted circle and a line segment. The length of the scan is determined by the region of interest , and it is independent of the size of the object. With few geometric restrictions on the curve, we show that we have an exact reconstruction. Numerical experiments demonstrate good image quality.

Les ``C-arm'' sont des systémes de radiologie interventionnelle fréquemment utilisés en salle d'opération ou au lit du patient. Des images 3D des structures anatomiques internes peuvent être calculées à partir de multiples radiographies acquises sur un ``C-arm mobile'' et isocentrique décrivant une trajectoire généralement circulaire autour du patient. Pour cela, la géométrie conique d'acquisition de chaque radiographie doit être précisément connue. Malheureusement, les C-arm se déforment en général au cours de la trajectoire. De plus leur motorisation engendre des oscillations non reproductibles. Ils doivent donc être calibrés au cours de l'acquisition. Ma thèse concerne la calibration intrinsèque d'un C-arm à partir de la détection de la projection du collimateur de la source dans les radiographies.Nous avons développé une méthode de détection de la projection des bords linéaires du collimateur. Elle surpasse les méthodes classiques comme le filtre de Canny sur données simulées ou réelles. La précision que nous obtenons sur l'angle et la position (phi,s) des droites est de l'ordre de: phi{RMS}=+/- 0.0045 degrees et s{RMS}=+/- 1.67 pixels. Nous avons évalué nos méthodes et les avons comparés à des méthodes classiques de calibration dans le cadre de la reconstruction 3D. / Mobile isocentric x-ray C-arm systems are an imaging tool used during a variety of interventional and image guided procedures. Three-dimensional images can be produced from multiple projection images of a patient or object as the C-arm rotates around the isocenter provided the C-arm geometry is known. Due to gravity affects and mechanical instabilities the C-arm source and detector geometry undergo significant non-ideal and possibly non reproducible deformation which requires a process of geometric calibration. This research investigates the use of the projection of the slightly closed x-ray tube collimator edges in the image field of view to provide the online intrinsic calibration of C-arm systems.A method of thick straight edge detection has been developed which outperforms the commonly used Canny filter edge detection technique in both simulation and real data investigations. This edge detection technique has exhibited excellent precision in detection of the edge angles and positions, (phi,s), in the presence of simulated C-arm deformation and image noise: phi{RMS} = +/- 0.0045 degrees and s{RMS} = +/- 1.67 pixels. Following this, the C-arm intrinsic calibration, by means of accurate edge detection, has been evaluated in the framework of 3D image reconstruction.

The historical development, current practice, and the future of interventional neuroradiology are intricately linked to the advancements in the imaging and devices used for neuroendovascular treatments. This thesis explores the advanced imaging potential of the C-arm imaging systems used in the neurointerventional suite and investigates the initial clinical experience with a new flow diverter device to treat the intracranial aneurysms. A cohort of aneurysmal SAH patients who developed delayed cerebral ischaemia (DCI) were prospectively studied with a new parenchymal blood volume (PBV) research protocol C-arm CT examination concurrent with a magnetic resonance (MR) imaging examination that included perfusion and diffusion weighted sequences. Using a robust quantitative volume-of-interest analysis, it was demonstrated that C-arm CT PBV measurements are in agreement with MR-PWI CBV and CBF, and the PBV represents a composite perfusion parameter with both blood-flow (≈60%) and blood-volume (≈40%) weightings. Subsequently, using a voxel-wise ROC curve analysis and MR-DWI, it was shown that using optimal thresholds, C-arm CT PBV measurements allow reliable demarcation of the irreversibly infarcted parenchyma. For evaluation of ischaemic parenchyma, the PBV measurements were reliable for moderate-to-severe ischaemia but were prone to underestimate the mild-to-moderate ischaemia. A catalogue of reference mean PBV measurements was then created for various anatomical regions encompassing the whole brain after excluding any locations with ongoing ischaemia or infarction. Next, using an ROI-based analysis of the C-arm CT projection data, steady-state contrast concentration assumption underlying the PBV calculations was investigated. It was demonstrated that for clinical scans, the ideal steady-state assumption is not fully met, however, for a large majority of C-arm CT examinations the temporal characteristics of TDCs closely approximate the expected ideal steady-state. The degree to which the TDC of a C-arm CT scan approximates the ideal steady-state was found to influence the resulting PBV measurements and their agreement to MR-CBV. Moreover, the temporal characteristics of TDCs showed inter-subject variation. Finally, the C-arm CT cross-sectional soft tissue images were demonstrated to be of adequate quality for the assessment of ventricles and for the detection of procedural vessel rupture. These findings advance the understanding of the nature of PBV parameter, establish the optimal PBV thresholds for infarction, provide reference PBV measurements, and highlight the limitations of C-arm CT PBV imaging. The work is of considerable clinical significance and has implications for implementation of C-arm CT PBV imaging in the interventional suite for management of patients with acute brain ischaemia. In regards to the initial clinical experience with the flow diversion treatment of intracranial aneurysms, the procedural, angiographic, and clinical outcomes were studied. Several pertinent technical and clinical issues were highlighted for this new treatment approach. Based on the observations made during this work, a new grading schema was then developed to monitor the angiographic outcomes after flow diversion treatment. Using the angiographic data for patients treated with FD, the new grading schema was demonstrated to be sufficiently sensitive to register gradual aneurysm occlusion and evaluate parent artery patency, with an excellent inter-rater reliability and applicability to various aneurysm morphologies. This work (largest multi-centre series at the time of its publication) informed the interventional neuroradiology community about the safety, efficacy, and outcomes of flow diversion treatment. Additionally, it provided a sensitive and reliable scale to evaluate the angiographic outcomes after flow diversion treatment, in both research and clinical practice.