Bakgrund: Utvecklingen av genomlysnings-baserade interventioner har varit framgångsrika de senaste årtiondena, då det gäller behandling av patienter. Införandet av genomlysning har dock medfört risker, för både patient och personal. Detta på grund av att stråldoser ökat i takt med en större efterfrågan på genomlysning och en utveckling av mer avancerade undersökningar. Med tanke på att stråldosen från intervention har en biologisk långtidseffekt, så är strålskydd ett upp-märksammat och återkommande ämne då det påverkar både sjukvårdspersonal, patienter och sam-hället. Brist på strålskydd och oaktsamhet hos operatörerna medför en ökad risk för strålningsindu-cerade skador. Eftersom antalet interventioner ständigt ökar så behövs även en ökad medvetenhet hos vårdpersonal kring vilka risker strålningen kan medföra och hur de kan undvikas. Syfte: Att beskriva vilka åtgärder som kan vidtas för att minska stråldosen för personal och patient vid angiografi/intervention. Metod: En systematisk litteraturstudie har använts. Resultat: I det sammanställda resultatet har flera olika strålskyddsåtgärder presenterats för att reducera stråldosen under intervention/angiografi. Genomlysningstid, modern teknik, uppdaterade inställningar i apparaturen och blyskydd har alla visat sig minska stråldosen markant till patient och personal. Utbildning och feedback ses även vara en viktig del i strålskyddsarbetet då det utgör grun-den för att riktlinjer kring strålskydd följs. Slutsats: Att det finns alternativa strålskyddsåtgärder vid IR- undersökningar/åtgärder är något som kan konstateras. Faktum är att en kombination av dessa åtgärder helt klart vore optimalt, för ökad säkerhet hos både personal och patienter vid exponering av strålning. / Background: The development of fluoroscopy-guided interventions the recent decades has resulted in a successful treatment of patients. However, the introduction of these diagnostic devices carry risks for both patients and staff. This is due to the fact that radiation doses increases in line with a greater demand for interventions and the development of advanced procedures. The radiation may cause long-term biological effects which makes radiation protection an important subject as it affects both staff, patients and society. Lack of radiation protection and negligence among operators cause an increased risk of radiation-induced damage. As the number of interventions constantly increase, improved knowledge is needed. Aim: The aim of this study is to describe which methods can be applied in order to reduce radiation doses for staff and patients in angiography / intervention. Method: A systematic study of existing literature. Results: The result shows several different radiation protection strategies to reduce the radiation dose during intervention / angiography. Fluoroscopy time, modern technology, updated settings in the device and lead protection have all been shown to reduce radiation dose significantly to both patients and staff. Education and feedback are also considered to be an important part of the radiation safety as they provide the basic guidelines on radiation protection. Conclusion: There is a lot of alternative radiation protection strategies in fluoroscopy-guided inter-ventions. In fact, a combination of these strategies would clearly be optimal for increased safety for both staff and patients exposed to radiation.

<p>This thesis consider enhancement of X-ray fluoroscopy image sequences. The purpose is to investigate the possibilities to improve the image enhancement in Biplanar 500, a fluoroscopy system developed by Swemac Medical Appliances, for use in orthopedic surgery.</p><p>An algorithm based on recursive filtering, for temporal noise suppression, and motion compensation, for avoidance of motion artifacts, is developed and tested on image sequences from the system. The motion compensation is done both globally, by using the theory of the shift theorem, and locally, by subtracting consecutive frames. Also a new type of contrast adjustment is presented, received with an unlinear mapping function.</p><p>The result is a noise reduced image sequence that shows no blurring effects upon motion. A brief study of the result shows, that both the image sequences with this algorithm applied and the contrast adjusted images are preferred by orthopedists compared to the present images in the system.</p>

This thesis consider enhancement of X-ray fluoroscopy image sequences. The purpose is to investigate the possibilities to improve the image enhancement in Biplanar 500, a fluoroscopy system developed by Swemac Medical Appliances, for use in orthopedic surgery. An algorithm based on recursive filtering, for temporal noise suppression, and motion compensation, for avoidance of motion artifacts, is developed and tested on image sequences from the system. The motion compensation is done both globally, by using the theory of the shift theorem, and locally, by subtracting consecutive frames. Also a new type of contrast adjustment is presented, received with an unlinear mapping function. The result is a noise reduced image sequence that shows no blurring effects upon motion. A brief study of the result shows, that both the image sequences with this algorithm applied and the contrast adjusted images are preferred by orthopedists compared to the present images in the system.

Dynamic assessment of three-dimensional (3D) joint kinematics is essential for understanding normal joint function as well as the effects of injury or disease. The knowledge of one or two series of bi-dimensional fluoroscopic projections of the joint in motion (mono-planar or bi-planar fluoroscopy), and the 3D model of the joint segments, were claimed to be sufficient to reconstruct the absolute and relative 6 Degrees Of Freedom (DOFs) pose of bones or prostheses in the 3D space. The software MultiTrack was developed at the Health Sciences and Technologies - Interdepartmental Center for Industrial Research (HST - ICIR) for the joint kinematics estimation with 3D Video Fluoroscopy (3DF) [1] using C++ language with ITK [2] segmentation & registration toolkit and VTK [3] visualization toolkit. An optimization procedure finds the 6 degrees of freedom pose that optimizes a metric quantifying the matching of the 3D model and its relevant projections. The metric, currently implemented in the software, is based on the contour segmentation of the object to be tracked and on the use of 3D adaptive distance maps (ADM) [4,5]. However, the contour extraction is a time consuming procedure for the user. Different methods were proposed in the literature to reduce the user interaction, each with its proper pros and cons. In the current thesis a few of the for-mentioned methods are discussed in order to evaluate each of them in terms of accuracy, speed and user dependency. At the final step the algorithm proposed by Mafhouz et al. [6], initially proposed for prostheses, is implemented inside the MultiTrack framework. To be properly characterized, the above method is tested on in vivo datasets and under various sources of error. / Η δυναμική αξιολόγηση της τρισδιάστατης (3D) κινηματικής των αρθρώσεων είναι απαραίτητη για την κατανόηση της φυσιολογικής λειτουργία των αρθρώσεων, καθώς και τις επιπτώσεις της κακώσεων ή παθήσεων . Η γνώση μιας ή δύο σειρών δυσδιάστατων ακτινοσκοπικών προβολών των αρθρώσεων σε κίνηση ( μονο - επίπεδη ή δι- επίπεδη ακτινοσκόπηση), και ενός τρισδιάστατου (3D) μοντέλου των επιμέρους τμημάτων των αρθρώσεων , κρίνεται επαρκής για να ανακατασκευαστούν τόσο οι απόλυτοι όσο και οι σχετικοί 6 βαθμοί ελευθερίας της θέσης των οστών ή των προσθετικών τμημάτων στον τρισδιάστατο χώρο. Το λογισμικό “MultiTrack” αναπτύχθηκε στις Επιστήμες Υγείας και Τεχνολογίες - Διατμηματικό Κέντρο Βιομηχανικών Ερευνών (HST-ICIR) έτσι ώστε να επιτευχθεί με ακρίβεια η εκτίμηση της κινηματικς των αρθρώσεων με τρισδιάστατη ακτινοσκόπηση (φθοροσκοπία) με βιντεοκαρέ (3DF) [1] χρησιμοποιώντας C++ γλώσσα προγραμματισμού σε συνδυασμό με τα εργαλεία κατακερματισμού & καταγραφής (segmentation & registration) ITK [2] και οπτικοποίησης (visualization) VTK [3]. Μια διαδικασία βελτιστοποίησης βρίσκει τους 6 βαθμούς ελευθερίας της θέσης που βελτιστοποιεί τη συνάρτηση ποσοτικοποίησης της συνάφειας του 3D μοντέλου και των σχετικών προβολών του. Η συνάρτηση ποσοτικοποίησης, έτσι όπως έχει υλοποιηθεί στο λογισμικό, βασίζεται στην κατάτμηση του περιγράμματος (contour segmentation) του υπό εξέταση αντικειμένου και στη χρήση τρισδιάστατων προσαρμοστικών χαρτών απόστασης (Adaptive Distance Map-ADM) [4,5]. Ωστόσο, η εξαγωγή του περιγράμματος είναι μια χρονοβόρα διαδικασία για το χρήστη. Διαφορετικές μέθοδοι έχουν προταθεί στη βιβλιογραφία για τη μείωση της αλληλεπίδρασης του χρήστη, η καθεμία με τα πλεονεκτήματα και τα μειονεκτήματα της. Στην παρούσα διπλωματική εργασία, αναλύονται μερικές από τις προαναφερθείσες μέθοδοι προκειμένου να αξιολογηθεί καθεμία από αυτές όσον αφορά την ακρίβεια, την ταχύτητα και την εξάρτηση της από το χρήστη. Στο τελικό στάδιο, ο αλγόριθμος που προτείνεται από τον Mafhouz [6] και χρησιμοποιήθηκε αρχικά για προθέσεις, υλοποιείται εντός του λογισμικού “MultiTrack”. Η παραπάνω μέθοδος για να χαρακτηριστεί πλήρως, έχει δοκιμαστεί σε in-νίνο δεδομένα και κάτω από διάφορες πηγές σφάλματος.

A number of interventional procedures such as cardiac catheterization, angiography and the deployment of endovascular devices are routinely performed using x-ray fluoroscopy. To minimize the patient’s exposure to ionizing radiation, each fluoroscopic image is acquired using a very low x-ray exposure (~ 1 uR at the detector). At such an exposure, most semiconductor-based digital flat panel detectors (FPD) are not x-ray quantum noise limited (QNL) due to the presence of electronic noise which substantially degrades their imaging performance. The goal of this thesis was to investigate how a FPD based on amorphous selenium (a-Se) with internal avalanche multiplication gain could be used for QNL fluoroscopic imaging at the lowest clinical exposures while satisfying all of the requirements of a FPD for interventional radiology. Towards this end, it was first determined whether a-Se can reliably provide avalanche multiplication gain in the solid-state. An experimental method was developed which enabled the application of sufficiently large electric field strengths across the a-Se. This method resulted in avalanche gains as high as 10000 at an applied field of 105 V/um using optical excitation. This was the first time such high avalanche gains have been reported in a solid-state detector based on an amorphous material. Secondly, it was investigated how the solid-state a-Se avalanche detector could be used to image X-rays at diagnostic radiographic energies (~ 75 kVp). A dual-layered direct-conversion FPD architecture was proposed. It consisted of an x-ray drift region and a charge avalanche multiplication region and was found to eliminate depth-dependent gain fluctuation noise. It was shown that electric field strength non-uniformities in the a-Se do not degrade the detective quantum efficiency (DQE). Lastly, it was determined whether the solid-state a-Se avalanche detector satisfies all of the requirements of interventional radiology. Experimental results have shown that the total noise produced by the detector is negligible and that QNL operation at the lowest fluoroscopic exposures is indeed possible without any adverse effects occurring at much larger radiographic exposures. In conclusion, no fundamental obstacles were found preventing the use of avalanche a-Se in next-generation solid-state QNL FPDs for use in interventional radiology.

Prostate cancer continues to be the most commonly diagnosed cancer among men. Brachytherapy has emerged as one of the definitive treatment options for early stage prostate cancer which entails permanent implantation of radioactive seeds into the prostate to eradicate the cancer with ionizing radiation. Successful brachytherapy requires the ability to perform dosimetry -which requires seed localization- during the procedure but such function is not available today. If dosimetry could be performed intraoperatively, physicians could implant additional seeds into the under-dosed portions of the prostate while the patient is still on the operating table. This thesis addresses the brachytherapy seed localization problem with introducing intensity based registration between transrectal ultrasound (TRUS) that shows only the prostate and a 3D seed model drawn from fluoroscopy that shows only the implanted seeds. The TRUS images are first filtered and compounded, and then registered to the seed model by using mutual information. A training phantom was implanted with 48 seeds and imaged. Various ultrasound filtering techniques were analyzed. The effect of false positives and false negatives in ultrasound was investigated by randomly masking seeds from the fluoroscopy volume or adding seeds to that in random locations. Furthermore, the effect of sparse and dense ultrasound data was analyzed by running the registration for ultrasound data with different spacing. The registration error remained consistently below clinical threshold and capture range was significantly larger than the initial guess guaranteed by the clinical workflow. This fully automated method provided excellent registration accuracy and robustness in phantom studies and promises to demonstrate clinically adequate performance on human data. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2008-09-27 12:35:16.691

A number of interventional procedures such as cardiac catheterization, angiography and the deployment of endovascular devices are routinely performed using x-ray fluoroscopy. To minimize the patient’s exposure to ionizing radiation, each fluoroscopic image is acquired using a very low x-ray exposure (~ 1 uR at the detector). At such an exposure, most semiconductor-based digital flat panel detectors (FPD) are not x-ray quantum noise limited (QNL) due to the presence of electronic noise which substantially degrades their imaging performance. The goal of this thesis was to investigate how a FPD based on amorphous selenium (a-Se) with internal avalanche multiplication gain could be used for QNL fluoroscopic imaging at the lowest clinical exposures while satisfying all of the requirements of a FPD for interventional radiology. Towards this end, it was first determined whether a-Se can reliably provide avalanche multiplication gain in the solid-state. An experimental method was developed which enabled the application of sufficiently large electric field strengths across the a-Se. This method resulted in avalanche gains as high as 10000 at an applied field of 105 V/um using optical excitation. This was the first time such high avalanche gains have been reported in a solid-state detector based on an amorphous material. Secondly, it was investigated how the solid-state a-Se avalanche detector could be used to image X-rays at diagnostic radiographic energies (~ 75 kVp). A dual-layered direct-conversion FPD architecture was proposed. It consisted of an x-ray drift region and a charge avalanche multiplication region and was found to eliminate depth-dependent gain fluctuation noise. It was shown that electric field strength non-uniformities in the a-Se do not degrade the detective quantum efficiency (DQE). Lastly, it was determined whether the solid-state a-Se avalanche detector satisfies all of the requirements of interventional radiology. Experimental results have shown that the total noise produced by the detector is negligible and that QNL operation at the lowest fluoroscopic exposures is indeed possible without any adverse effects occurring at much larger radiographic exposures. In conclusion, no fundamental obstacles were found preventing the use of avalanche a-Se in next-generation solid-state QNL FPDs for use in interventional radiology.

Thesis (Ph. D.)--University of Chicago, Dept. of Radiology, August 2000. / Includes bibliographical references. Also available on the Internet.

BACKGROUND: Although the Image Quality (IQ) indices calculated by objective Model observers contains more favourable characteristics compared to Figure Of Merits (FOM) derived from the more common subjective evaluations of modern digital diagnostic fluoroscopy units, like CDRAD or the Leeds test-objects, practical issues in form of limited access to unprocessed raw data and intricate laboratory measurements have made the conventional computational methods too inefficient and laborious. One approach of the Statistical Decision Variables (CDV) analysis, made available in the FluoroQuality software, overcome these limitations by calculating the SNR2rate from information entirely based on image frames directly obtained from the imaging system, operating in its usual clinical mode.      AIM: The overall aim of the project has been to make the proposed Model observer methodology readily available and verified for use in common IQ tests that takes place in a hospital based on simple measuring procedures with the default image enhancement techniques turned on. This includes conversion of FluoroQuality to MATLAB, assessment of its applicability on a modern digital unit by means of comparisons of measured SNR2rate with the expected linear response predicted by the classical Rose model, assessment of the methods limiting and optimized imaging conditions (with regard to both equipment and software parameters) and dose-efficiency measurements of the SNR2rate/Doserate Dose-to-information (DI) index including both routine quality control of the detector and equipment parameter analyses.      MATERIALS AND METHODS: A Siemens Axiom Artis Zee MP diagnostic fluoroscopy unit, a Diamentor transmission ionisation chamber and a small T20 solid state detector have been used for acquisition of image data and measurements of Air Kerma-area product rate (KAP-rate) and Entrance Surface Air Kerma rate (ESAK-rate without backscatter). Two sets of separate non-attached test-details, of aluminium and tissue equivalent materials respectively, and a Leeds test object were used as contrasting signals. Dose-efficiency measurements consisted of variation of 4 different parameters: Source-Object-Distance, Phantom PMMA thickness, Field size and Dose rate setting. In addition to these, dimensions of the test details as well as computational parameters of the software, like ROI size and number of frames, were included in the theoretical analyses.      RESULTS: FluoroQuality has successfully been converted to MATLAB and the method has been verified with SNR2rate in accordance with the Rose model with only small deviations observed in contrast analyses, most likely reflecting the methods sensitivity in observing non-linear effects. Useful guidelines for measurement procedures with regard to accuracy and precision have been derived from the studies. Results from measurements of the (squared) DI-indices indicates comparable precision (≤ 8%) with the highest performing visual evaluations but with higher accuracy and reproducibility. What still remains for the method to compete with subjective routine QC tests is to integrate the SNR2rate measurements in an efficient enough QA program.

Introdução: O sinal da aspiração faríngea (SAF) e o sinal do pigarrear (SPIG), manifestações clínicas em geral relacionadas, respectivamente, a doenças de vias aéreas superiores e inferiores, são expressões de mecanismos de defesa de natureza mecânica que atuam na limpeza do trato respiratório, e com freqüência encontram-se associados à tosse crônica. Repercutem especialmente em nível faríngeo, com as correspondentes modificações estruturais desse compartimento. Objetivo: Descrever e analisar as modificações anatômicas e características fisiológicas que servem de base para a ocorrência do SAF e do SPIG. Métodos: Estudo clínico observacional onde, foram selecionados 30 indivíduos adultos de ambos os sexos, portadores de rinussinusite crônica, fora de agudização, os quais foram submetidos a exames de imagem, estáticos (radiográficos) e dinâmicos (fluoroscópicos), de modo a ser possível estudar as alterações anatômicas nos momentos mencionados (SAF, SPIG), e durante a situação de repouso (REP). Os pacientes eram colocados em posição ortostática, de perfil, buscando-se, com isto, reduzir os efeitos da sobreposição de tecidos, objetivando tornar as mensurações mais acuradas. Cada um dos 30 indivíduos foi estudado nas três situações: em repouso (REP), em manobra de aspiração faríngea (SAF), e durante o ato do pigarrear SPIG). Usaram-se testes de média para comparações entre as mensurações (teste T e ANOVA), intervalos de confiança de 95,0 %, adotando-se nível de significância de 5,0 %. Resultados: Encontrou-se a área transversa da faringe medindo 4,13±1,339 cm² na posição de repouso, 1,879±0,950 cm² durante a manobra de aspiração, e 5,280±1,421 cm² durante o pigarrear. Esses três valores foram todos significativamente diferentes entre si (p<0,001). A maior variação com relação ao repouso ocorreu no SAF (120,0% menor), enquanto que no SPIG foi em torno de 30,0% maior. Os valores foram menores entre as mulheres, mas a variabilidade foi similar em ambos os sexos. Conclusão: A área da secção transversa da faringe, mensurada no nível da primeira vértebra cervical de indivíduos adultos, mostrou-se significativamente menor durante a manobra inspiratória (SAF), em comparação com a situação de repouso (REP), enquanto que a do pigarrear (SPIG) foi significativamente maior. As modificações do calibre da faringe, em especial o acentuado estreitamento durante o SAF, associadas a movimentos vibratórios das estruturas locais, devem conferir a esse compartimento maior eficiência na remoção das secreções do trato respiratório. / Introduction: The signs of both pharyngeal aspiration (SPA) and phlegm in the throat (SPT), clinical manifestations generally related, respectively, to either upper or lower diseases of the airways, are expressions of mechanic defense mechanisms for respiratory tract cleaning, frequently associated to chronic cough. They have repercussion mainly at pharyngeal level, with the correspondent structural modifications of that compartment. Objective: To describe the anatomic modifications and physiologic characteristics in which are based the grounds for the SPA and SPT occurrence. Methods: Clinical and observational study in which were selected 30 of both sex adult individuals, all with inflammatory upper airways disease, with the purpose to specially study the alterations in morphology of the pharynx, which occurs during the SPA and SPT expression. For that, the individuals in orthostatic position were submitted to static (radiographic) and dynamic (fluoroscopy) image exams, in profile projections, aiming with this to reduce the tissue superposition and to obtain more accurate measurements. Each of the 30 individuals were studied in three situations: at rest (RST), in SPA and SPT. Tests of media (T, ANOVA) were used for comparisons between measurements, adopting a 5.0% significance level. Results: It was found the transverse area of pharynx measuring 4.133±1.339 cm2 in the rest (RST) position, 1.879±0.950 cm2 during pharyngeal aspiration (SPA), and 5.280±1.421 cm2 in SPT – values that were significantly different (P<0.001). In relation to the rest situation, the most accented variation occurred in SPA (120.0% smaller), whereas in SPT it was 30.0% greater. The values were smaller among females, but their variability was similar in both sexes in all the three situations. Conclusions: In comparison to the rest situation (RST), the transverse section of the pharynx, measured at the first cervical vertebra, was significantly smaller during the aspiration (SPA), and greater on the SPT maneuver. The modifications of the pharynx caliber, specially its accented narrowing associated to vibratory movements of the local anatomic structures, should be confer to that compartment a better efficiency for secretion removal from the respiratory tract.