Ces travaux de thèse s’inscrivent dans la problématique de développement de transformateurs planar pour l’intégration de puissance, dans le contexte de l’avion plus électrique (More Electric Aircraft – MEA) où les contraintes de volume et de poids sont primordiales. Les composants magnétiques restent en effet un frein à l’intégration des systèmes d’Electronique de Puissance et les composants planar (transformateurs et inductances) offrent une alternative intéressante aux composants bobinés pour la réduction de la taille des convertisseurs.Dans ce manuscrit, des méthodes, un outil de dimensionnement et des prototypes de transformateurs planar (2 et 3 enroulements) en technologie feuillard et PCB sont développés pour des applications de convertisseur DC/DC aéronautique. Dans un premier temps, les modèles permettant le calcul des pertes, l'estimation de l'élévation de température et le calcul de l’inductance de fuite sont présentés et comparés afin de concevoir des outils de calculs pour la conception. Dans un deuxième temps, il est montré que la modification de la forme des angles des spires rectangulaires permet de réduire significativement les pertes cuivre HF. Sur la base de ces outils et résultats, des prototypes de transformateurs planar à 3 enroulements en PCB multicouches sont développés. De nombreux prototypes sont caractérisés et valident les modèles de dimensionnement proposés. Enfin, l’un de ces prototypes est intégré et testé dans un convertisseur de puissance DC/DC de 3.75kW mettant en évidence les gains obtenus. / These thesis works deal with the issue of the planar transformers development for power integration, in the context of the More Electric Aircraft (MEA), where the constraints of volume and weight are paramount. Magnetic components remain a hindrance to the integration of Power Electronics systems and planar components (transformers and inductors) offer an interesting alternative to wound components for reducing the size of converters.In these works, methods, a sizing tool and prototypes of planar transformers (2 and 3 windings) in strip and PCB technology are developed for aeronautical DC / DC converter applications. Firstly, the models allowing the calculation of the losses, the estimation of the temperature rise and the calculation of the leakage inductance are presented and compared in order to design calculation tools for engineers. In a second step, it is shown that the modification of the shape of the angles of rectangular turns makes it possible to significantly reduce the HF copper losses.Based on these tools and results, prototypes of 3-windings planar transformers in multilayer PCBs are developed. Many prototypes are characterized and validate the proposed designing models. Finally, one of these prototypes is integrated and tested in a DC / DC power converter of 3.75kW highlighting the gains obtained.

Receiver systems utilising planar technologies are prevalent in telescopes observing at radio to sub-millimetre wavelengths. Receiver components using planar technologies are generally smaller, have reduced mass and are cheaper to manufacture than waveguide-based alternatives. Given that modern-day detectors are capable of reaching the fundamental photon noise limit, increases in the sensitivity of telescopes are frequently attained by increasing the total number of detectors in the receivers. The development of components utilising planar technologies facilitates the demand for large numbers of detectors, whilst minimising the size, mass and manufacturing cost of the receiver. After a review and study of existing concepts in radio to sub-mm telescopes and their receivers, this thesis develops planar components that couple the radiation from the telescope's optics onto the focal plane. Two components are developed; a W- band (75-110 GHz) planar antenna-coupled flat mesh lens designed for the receiver of a Cosmic Microwave Background (CMB) B-mode experiment, and an L-band (1- 2 GHz) horn-coupled planar orthomode transducer designed for the receiver of the FAST telescope. The first developments of a planar antenna-coupled flat mesh lens are presented. The design is driven by the requirement to mitigate beam systematics to prevent pollution of the CMB B-mode signal. In the first instance, a waveguide-coupled mesh lens is characterised. The radiation patterns of the waveguide-coupled mesh lens have -3 dB beam widths between 26 and 19 degrees, beam ellipticity <10%, and cross-polarisation.

Les composants magnétiques planaires (inductance et transformateur) occupent une place importante dans certains circuits intégrés utilisés en haute fréquence. Leur miniaturisation et leur intégration vont de pair avec celles des circuits électroniques qui évoluent constamment surtout pour les appareils portables. Quelques travaux scientifiques ont permis d’identifier les différents mécanismes à l’origine de pertes dans les composants magnétiques planaires, afin de les limiter. Les pertes dans les enroulements sont classiquement prises en compte par une résistance r(f) fonction de la fréquence. La détermination, à partir des paramètres S obtenus par mesure ou simulation, de la résistance r(f) constitue à ce jour un sujet d’étude à part entière, les paramètres S étant les seuls paramètres que l’on peut obtenir au-delà de la centaine de MHz. Pour contribuer à la résolution de ce problème, nous avons proposé une méthode prenant en compte toutes les pertes dans le bobinage. Cette méthode de détermination de la résistance en fonction de la fréquence se fait dans trois domaines de fréquence : - en très basse fréquence, la rDC est obtenue par calcul ou mesurée à l’aide d’un matériel basse fréquence, - aux "moyennes fréquences" lorsque les impédances R et Lω ne sont pas trop différentes, les phénomènes capacitifs pouvant être négligés, - aux résonances en très haute fréquence. L’application de cette méthode sur trois structures différentes (inductance à air de plusieurs spires, à air à une spire en oméga et à une couche de matériau magnétique) a permis de : - observer une bonne corrélation entre simulation et mesure, -valider l’évolution des pertes en fonction de la fréquence, -séparer les effets de peau et de proximité, -séparer les pertes fer et les pertes cuivre pour une inductance à couche magnétique / Planar magnetic components (transformer and inductor) have become a big part in some integrated circuits used in high frequency. Miniaturization and integration of magnetic components go hand in hand with the ones of electronics that constantly evolves especially for portable devices. A few scientific studies have identified the different mechanisms of losses in planar magnetic components. Winding losses are generally taken into account using a resistance r(f) versus frequency.The use of scattering parameters S to determine resistance r(f) represents a comprehensive research project ; S parameters that can be obtained either by measurement or by simulation, are the only parameters which one can get at high frequencies (above 100MHz). To solve this problem, we have proposed a method taking into account all winding losses. Our approach for determining r(f) has to be applied in 3 frequency domains: - at very low frequency, r(f) = rDC and its value is either calculated or measured using low frequency equipment, - in the middle frequency range, capacitive coupling can be neglected while impedances R and Lω are in the same order of magnitude, - at very high resonance frequencies.This method has been implemented for 3 different structures (coreless inductor with several turns of coil, Omega shape coreless inductor with one turn and inductor with a magnetic layer) leads to : - observe a good correlation between simulation and measurement, - validate the evolution of losses versus frequency, - separate skin effects and proximity effects, - separate iron losses and winding losses

Made available in DSpace on 2014-06-11T19:25:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-03-01Bitstream added on 2014-06-13T18:28:55Z : No. of bitstreams: 1 saggioro_bz_me_rcla.pdf: 2011105 bytes, checksum: 3a55198b06d17033aac4826618ba3503 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Superfícies de vidro plano comercial (flotado) e de vidros sintetizados no laboratório com diferentes concentrações em massa de SnO2 foram expostos aos vapores resultantes da decomposição de KNO3 fundido a uma temperatura um pouco abaixo da temperatura de transição vítrea. Medidas de EDS mostram um aumento da concentração dos íons K+ na superfície com o aumento do tempo de exposição aos vapores. Alguns destes íons migraram para o interior dos vidros, conforme mostram as medidas do perfil de concentração. Os coeficientes de difusão foram determinados utilizando a técnica de Bolztzman-Matano. Esta mudança na concentração de K+ provocou modificações estruturais na superfície, alterando algumas de suas propriedades físico-químicas. Espectros de reflexão no infravermelho foram realizadas nestas amostras e mostraram que as alterações mais pronunciadas ocorreram na banda em tono de 950 cm-1. A dureza Vickers aumenta com o tempo de exposição. O índice de refração foi determinado pelos métodos de Brewster e refratometria Abbe. Constatou-se que quanto maior o tempo de exposição aos vapores, maior o valor do índice de refração das amostras. Foi verificado se esta nova técnica de troca iônica, isto é, por exposição a vapores, é propicia na preparação de dispositivos baseados em guias de ondas planares, utilizando a técnica de acoplamento de prisma. Vidros sintetizados também foram submetidos a testes de dilatometria com o intuito de determinar a temperatura de transição vítrea e calcular o coeficiente de expansão térmica. Medidas de densidade foram realizadas utilizando o principio de Arquimedes. Há diversas evidências experimentais que o estanho incorporado à estrutura vítrea atua como cátion formador de vidros, e que inibe a difusão iônica. / Surfaces of commercial plane glass (floated) and glasses synthesized in laboratory with different concentrations of SnO2 were exposed to vapors resulting from the decomposition of molten KNO3 at temperatures somewhat below the glass transitions. EDS measurements show an increase of the K+ concentration at the surfaces during the time of exposition to the vapors. Some of these ions migrate into the near surface layers of the samples, according to the measured concentration profiles. Diffusion coefficients were determined using the Bolztzman-Matano technique. The changes in concentration promote structural modifications at the surfaces, changing some of the physico-chemical properties of the glasses. Reflectance spectra in the infrared were carried out in these samples and one observe that the most pronounced change occurred around 950 cm-1. The Vickers hardness increases with the exposition time. The refractive index was determined by Brewster method and by Abbe refractometry. The longer the time of exposition to the vapors, the higher was the refractive index of the samples. This new technique of ionic exchange, that is, the exposition to vapors, was tested to verify if it is appropriate to prepare planar waveguide devices, and the coupling prism method was employed. Synthesized glasses were also subjected to dilatometric tests in order to determine the glass transition temperature, Tg, and the average thermal expansion coefficient, a. Density measurements were performed using Archimedes principle. There are several experimental evidences that tin is incorporated in the glass structure as a glass former cation, and it hinders ionic diffusion.

The present work studies instantaneous motion of smooth planar and spatial objects in unilateral point contacts. The traditional first-order instantaneous kinematic analysis is found insufficient to explain many common physical scenarios. The present work looks beyond the velocity state of motion for a comprehensive understanding through higher-order kinematic analysis of the above system. The methodology proposed herein is a Euclidean space approach to second-order motion space analysis of objects in point contacts. The geometries of the objects are approximated up to second-order in the differential vicinity of the point of contact; meaning, up to curvature at the point of contact. The instantaneous motion is approximated up to second-order kinematics, i.e., up to acceleration state. The basic approach consists of impressing an instantaneous motion upon one object while holding the other fixed which is in a single point contact initially, and observing for one of the following three states: penetration, separation, and persistence of contact between the two objects. These three states are characterized by the interference between the geometries of the objects. Penetration and separation of two curves for rotation about points on the plane is geometrically studied based on the relative configuration of the osculating circles at the point of contact. It is shown that the plane is partitioned into four regions of rotation centers. Partitioning of the plane into motion space regions at a contact provided a geometrical framework compose the motion space for multiple contacts. The applications include second-order form-closure (SFC) and synthesis of kinematic pairs. To explore the consequence of a generic motion, an analytical scheme is formulated using the screw theoretic concepts of twist and twist-derivative. It is shown that the characteristics of second-order motions at a single contact depends only upon the geometric kinematic properties of the motion; meaning, the motion characteristics are time-independent. The geometric conditions for the second-order motion that will be admissible or restrained at a contact are not available in the existing literature on \second-order mobility". The classical Euler-Savary equation for enveloping curves is found to represent the condition which is both necessary and sufficient for the second-order roll-slide motion. An elegant generalized geometric characterization of second-order motions is derived. This is made use for deriving condition of immobilization of, planar mechanisms with up to 2-degrees-of-freedom (d.o.f.), with a single point contact. Illustrative examples of four-bar and 2R-mechanisms are presented. Rapid prototyped model of the four-bar mechanism is fabricated and the SFC theory is verified satisfactorily. Through a novel use of Meusnier's theorem, rotational motion characteristics of planar curves in a point contact is used to determine the patterns and distribution of admissible axes of rotation in space for two surfaces in a single point contact. In the generalized analytical method of motion space analysis, the surfaces are locally represented in Monge's form up to second-order terms and motion is represented using twist and twist-derivative. An analytical framework for the second-order motion space analysis of surfaces with multiple contacts has been developed. Using this procedure, pairs of objects are analyzed for SFC and equivalent lower kinematic pair freedom. Revolute and planar joints with two contacts, prismatic joint with three contacts, SFC of regular concave spherical tetrahedron and regular tetrahedron with four contacts are demonstrated. Although conventional first-order studies demand seven contact points for form-closure, within the context of second-order motion, the present study established that, under special geometric conditions relative immobilization of two smooth objects can be enabled with much fewer contacts. Conditions for immobilization using three and two smooth contacts have been derived. Using contact kinematics equations based on higher-order reciprocity, an instantaneous spatial higher pair to lower pair substitute-connection which is kinematically equivalent up to acceleration analysis for two smooth surfaces in persistent point contact is derived. An illustrative example of a three-link direct-contact mechanism is presented.

Este trabalho tem como objetivo desenvolver um método numérico para simular escoamentos incompressíveis, isotérmicos, confinados ou com superfícies livres, de fuidos viscoelásticos governados pelos modelos integrais de Maxwell e K-BKZ (Kaye-Bernstein, Kearsley e Zapas). A técnica numérica apresentada é uma extensão do método GENSMAC (Tomé McKee - J. Comp. Phys., (110), pp 171--186, 1994 ) para a solução das equações de conservação, juntamente com as equações constitutivas integrais de Maxwell e K-BKZ. As equações governantes são resolvidas pelo método de diferenças finitas em uma malha deslocada. O tensor de Finger, B_t\'(t) é calculado com base nas idéias do método de campos de deformação (Peters et al. - J. Non-Newtonian Fluid Mech. (89), de maneira que não há a necessidade de seguir a trajetória da partícula de fuido para descrever a história de deformação da partícula. Uma abordagem diferente para a discretização do instante passado é utilizada e o tensor de Finger e o tensor das tensões são calculados utilizando um método de segunda ordem. A validação do método numérico descrito nesse trabalho foi feita utilizando o escoamento em um canal bidimensional e a solução numérica obtida para a velocidade e para as componentes de tensão com o modelo de Maxwell foram comparadas com as respectivas soluções analíticas no estado estacionário, mostrando excelente concordância. Os resultados numéricos para a simulação do escoamento em uma contração planar 4 : 1 mostraram bons resultados, tanto qualitativos quanto quantitativos, quando comparados com os resultados experimentais de Quinzani et al. ( J. Non-Newtonian Fluid Mech. (52), pp 1?36, 1994 ). Além disso, utilizando os modelos Maxwel e K-BKZ, o escoamento em uma contração planar 4 : 1 foi simulado para vários números de Weissenberg e os resultados obtidos estão de acordo com os encontrados na literatura. Resultados numéricos de escoamentos com superfícies livres modelados pelas equações integrais de Maxwell e K-BKZ são apresentados. Em particular, a simulação numérica do jato oscilante para diferentes números de Weissenberg e diferentes números de Reynolds é apresentada. / The aim of this work is to develop a numerical technique for simulating incompressible, isothermal, free surface (also con¯ned) viscoelastic flows of fuids governed by the integral models of Maxwell and K-BKZ (Kaye-Bernstein, Kearsley and Zapas). The numerical technique described herein is an extension of the GENSMAC method (Tome and McKee, J. Comput. Phys., 110, pp. 171-186, 1994) to the solution of the momentuum and mass conservation equations together with the integral constitutive Maxwell and K-BKZ equations. The governing equations are solved by the finite difference method on a staggered grid using a Marker-and-Cell approach. The fluid is represented by marker particles on the fluid surface only. This provides the visualization and location of the fluid free surface so that the free surface stress conditions can be applied. The Finger tensor Bt0(t) is computed using the ideias of the deformation fields method (Peters et al. J. Non-Newtonian Fluid Mech., 89, pp. 209-228, 2001) so that it is not necessary to track a fluid particle in order to calculate its deformation history. However, in this work modifcations to the deformation fields method are introduced: the past time is discretized using a different formula, the Finger tensor Bt0(x; t) is obtained by a second order method and the stress tensor ? (x; t) is computed by a second order quadrature formula. The numerical method presented in this work is validated by simulating the flow of a Maxwell fluid in a two-dimensional channel and the numerical solutions of the velocity and the stress components are compared with the respective analytic solutions providing a good agreement. Further, the flow through a 4:1 planar contraction of a specific fuid studied experimentally by Quinzani et al. (J. Non-Newtonian Fluid Mech., 52, pp. 1-36, 1994) was simulated and the numerical results were compared qualitatively and quantitatively with the experimental results and very good agreement was obtained. The Maxwell and the K-BKZ models were applied to simulate the 4:1 planar contraction problem using various Weissenberg numbers and the numerical results were in agreement with those published in the literature. Finally, numerical results of free surface flows using the Maxwell and K-BKZ integral constitutive equations are presented. In particular, the numerical simulation of jet buckling using several Weissenberg numbers and various Reynolds numbers are presented

Les composants magnétiques en technologie planar répondent aux exigences actuelles de l’Electronique de Puissance (EP), à savoir la montée en fréquence de commutation des structures d’EP et la réduction du volume des convertisseurs. La première tendance impose des contraintes fortes en termes de compatibilité électromagnétique (CEM) des équipements. Ces dernières doivent être prises en compte par les ingénieurs dès la phase conception des convertisseurs en se basant sur des modèles fiables, peu développés pour les composants planar dans la littérature scientifique. Ce travail de thèse porte ainsi sur la modélisation des composants planar pour applications aux filtres CEM. Différentes méthodes sont développées au cours de cette thèse pour arriver à évaluer de manière fine les éléments parasites des inductances planar de mode commun : capacités parasites et inductances de fuite. Une partie du travail a porté sur la modélisation par circuits équivalents du comportement fréquentiel des inductances de MC. Une approche automatisée, basée sur un algorithme de fitting a ainsi été développée pour élaborer des circuits équivalents fiables et robustes. Des approches analytiques (Décomposition du Champ Electrique) et semi-analytiques (Fonctions de Green) ont aussi été proposées pour évaluer les valeurs des éléments parasites. La dernière partie de la thèse est plus orientée conception, avec la réalisation de deux structures de composants innovantes, la première se basant sur une technique de compensation des capacités parasites à l’aide d’éléments parasites structuraux et la seconde sur l’association de deux noyaux magnétiques, possédant matériaux et géométries différentes / The magnetic components with planar technology join in the current trends in Power Electronics (PE), namely increasing the switching frequency of PE structures and reducing the size of the power converters. The first tendency imposes strong constraints in terms of electromagnetic compatibility of equipments. The latter has to be considered by engineers at the beginning of the design of Power converters on the basis of reliable models, which are not sufficiently developed for planar components in scientific literature. This PhD work thereby focuses on the modeling of planar components for the applications of EMI filters. Different methods are developed during this study in order to accurately evaluate the parasitic elements of planar common-mode chokes: parasitic capacitances and leakage inductances. A part of this dissertation concerns the equivalent circuit modeling of the frequency behavior of CM chokes. An automated approach, based on a fitting algorithm developed for elaborating reliable and robust equivalent circuits. Analytical approaches (Electric Field Decomposition) and semi-analytical (Green’s Function) are proposed as well for calculating the values of these parasitic elements. The last part of this dissertation is oriented to conception, with the realization of two structures of innovative components, the first one based on a parasitic capacitance cancellation technique using structural parasitic elements and the second one on the association of two magnetic cores with different materials and geometries

Avec un encombrement minimal et rendement de 99% les transformateurs planars haute fréquence sont des solutions technologiques importantes pour les systèmes de conversion et de conditionnement de l’énergie électrique en électronique de puissance. L’objectif de l’étude consiste à rechercher un modèle du composant permettant à la fois de simuler son comportement dans un circuit d’électronique de puissance et d’optimiser ses performances lors de sa conception. Les modèles proposés prennent en compte les propriétés physiques et géométriques du composant. Les validations sont basées sur des confrontations avec les mesures. Une autre motivation forte de ce travail est que les modélisations numériques doivent prendre en compte simultanément les effets des courants induits et les capacités parasites, ce qui conduit, en haute fréquence, à des besoins prohibitifs en termes de capacité mémoire ou de temps de calcul. En se limitant aux transformateurs planar. La modélisation (dite LEEC) présentée ici s’appuie sur une discrétisation à échelle intermédiaire : spire par spire, c’est-à-dire couche par couche. Elle assemble deux approches analytiques déjà introduites par l’équipe : la première traite les aspects électrocinétiques (incluant les courants induits) et magnétiques et l’autre les aspects électrostatiques. Les circuits à constantes localisées basés sur la méthode LEEC montrent un très bon accord avec toutes les mesures jusqu’à 40 MHz. Des outils numériques sont aussi développés pour faciliter l’obtention de ces différents circuits en partant : soit de la description du composant, soit de mesures d’impédances. Pour compléter, la représentation des capacités d’un transformateur quelconque, développée en plusieurs étapes par l’équipe, est résumée et des précautions expérimentales originales appliquées à l’impédancemétrie sont exposées dans le détail. D’autres travaux visant à élargir le champ d’application de la méthode LEEC sont également présentés. / With a small footprint and volumes and 99% efficiency the high frequency Planar transformers are solutions for major power conversion systems in power electronics. The objective of the study is to find Models to both simulate its behavior in a power electronics circuit and optimize its performance during its design. The proposed models take into account the physical and geometrical properties of the component. Validations are based on confrontation with measurements. Another strong motivation of this work is the numerical modeling must take into account both the effects of induced currents and parasitic capacitances, this level of modeling needs prohibitive sizes in terms of memory and computation time. Modeling (called LEEP) presented here is based on a intermediate scale discretization: turn by turn (conducting layer by conducting layer). It combines two analytical approaches already introduced by our team: the first deals with aspects electrokinetic (including induced currents) and magnetic and electrostatic aspects. Lumped circuits based on the method LEEC show a very good agreement with measurements up to 40 MHz. Software tools are also being developed to facilitate the achievement of these circuits either from the component description, or impedance measurements. In order to complete the modeling the capacitive behavior of any transformer is presented (historical development by our team is also shown in details). New experimental precautions and methodology for impedance measurements is detailed in this work. Other works aiming to extend the LEEC model are also shown.

The thesis describes the radiation of dipole antennas in near field area. More methods for evaluation of spatial dipole field arrangement are compared. The work target for practical use is to create software for simulation of near field values placed in planar or cylindrical observation plane. The computer programme is applicable to single dipole or dipole array. The limits for human body exposition of non-ionizing radiation are here implemented for compliance purpose in hygienic evaluations. The simulated results of field distribution are possible to display as graphs or save to data file. The results of own calculation are compared with results obtained by some commercial software as well by measurement of field components under model conditions.

Thesis (MSc (Medical Imaging and Clinical Oncology. Nuclear Medicine))--University of Stellenbosch, 2010. / ENGLISH SUMMARY: Introduction: Bone scintigraphy is used extensively in evaluating metastatic disease. There are currently no clear recommendations for the use of SPECT/CT in metastatic bone disease. Existing procedural guidelines from the Society of Nuclear Medicine (SNM) for SPECT/CT do not provide specific indications for use of SPECT/CT in bone scintigraphy, and there are currently no other guidelines for the use of SPECT/CT in bone scintigraphy that the author is aware of. The aim of this study was to investigate the additional value of SPECT/CT, and to identify the clinical indications for which SPECT/CT is most useful in patients with suspected bone metastases. Subjects and Methods: Forty-two patients with equivocal lesions on planar scintigraphy were prospectively recruited and planar imaging, SPECT, and SPECT/CT done on all patients. On reading of SPECT and then SPECT/CT, patients and individual lesions were classified as malignant, benign or equivocal. Radiological studies and available clinical information were also used during reading of scans. Review of clinical information, radiological studies and/or follow-up bone scans were used as gold standard. The results of the SPECT and SPECT/CT were compared in terms of proportion of equivocal findings and accuracy. Results: Forty-two patients with 189 skeletal lesions were examined. There was a diverse variety of primary tumours, although the majority had breast (n=22) or prostate cancer (n=8). Overall, SPECT/CT resulted in a significant reduction in the proportion of equivocal findings on both a patient-wise (p=0.0015) and lesion-wise basis (p<0.0001). The overall accuracy of SPECT/CT was significantly higher than that of SPECT on both a patient-wise (p=0.0026) and lesion-wise basis (p<0.0001). Generally SPECT/CT decreased the proportion of equivocal findings and increased the accuracy independent of the presence of bone pain, type of primary tumour, or skeletal region involved. SPECT/CT did not significantly improve the diagnostic confidence of readers in equivocal lumbar lesions although accuracy was significantly improved in this region. Conclusion: SPECT/CT performs significantly better than SPECT alone for the interpretation of equivocal planar lesions. There is no evidence that the benefit of SPECT/CT is dependent on the type of primary tumour or the presence of bone pain. Where resources are limited, SPECT/CT is indicated only in those patients in whom correct classification of the lesions in question is expected to alter the patient’s management. SPECT/CT images should be interpreted with the aid of a diagnostic radiologist or nuclear medicine physicians should acquire sufficient experience in Computed Tomographic image interpretation in order to optimise diagnostic benefit from SPECT/CT. / AFRIKAANSE OPSOMMING: Inleiding: Beenflikkergrafie word wyd vir die evaluering van metastatiese siekte gebruik. Daar bestaan tans geen duidelike aanbevelings vir die gebruik van Enkelfotonemissie rekenaartomografie gekombineer met rekenaartomografie (EFERT/RT, Engels SPECT/CT) in metastatiese beensiekte nie. Bestaande riglyne van die Amerikaanse Society of Nuclear Medicine (SNM) vir EFERT/RT gee nie spesifieke indikasies vir die gebruik van EFERT/RT in beenflikkergrafie nie, en daar is tans geen ander riglyne waarvan die outeur bewus is nie. Die doel van hierdie studie was om die bykomende waarde van EFERT/RT te ondersoek, en om dié kliniese indikasies waar EFERT/RT in pasiënte met vermoedelike beenmetastases mees nuttig sal wees, te identifiseer. Pasiënte en Metodes: Twee en veertig pasiënte met twyfelagtige letsels op planare skeletflikkergrafie is prospektief geselekteer en planare beelding, EFERT en EFERT/RT is op alle pasiënte gedoen. Tydens beoordeling van EFERT en daarna EFERT/RT beelde is pasiënte en individuele letsels as maligne, benigne of twyfelagtig geklassifiseer. Radiologiese studies en beskikbare kliniese inligting is ook tydens interpretasie van flikkergramme gebruik. Kliniese inligting, radiologiese studies en/of opvolg beenflikkergramme is as goue standaard gebruik. Die resultate van EFERT en EFERT/RT is ten opsigte van die aantal twyfelagtige bevindings en akkuraatheid vergelyk. Resultate: Twee en veertig pasiënte met 189 skeletale letsels is ondersoek. Daar was ‘n verskeidenheid van primêre tumore, maar die meerderheid van pasiënte het borsvi (n=22) of prostaatkanker (n=8) gehad. Die gebruik van EFERT/RT het gelei tot ‘n betekenisvolle afname in die aantal twyfelagtige bevindings, beide op ‘n pasiënt- en ‘n letselbasis (p=0.0015 en p<0.0001 onderskeidelik). Die algehele akkuraatheid van EFERT/RT was betekenisvol hoër as die van EFERT alleen, beide op pasiënt- en op letselbasis (p=0.0026 en p<0.0001 onderskeidelik). Oor die algemeen het EFERT/RT die aantal twyfelagtige letsels verminder en die akkuraatheid verhoog, ongeag die teenwoordigheid van beenpyn, die tipe primêre tumor of die area van die skelet wat betrokke was. In twyfelagtige lumbale letsels het EFERT/RT nie die diagnostiese vertroue van beoordelaars van flikkergramme verhoog nie, alhoewel die akkuraatheid vir hierdie gebied wel betekenisvol toegeneem het. Gevolgtrekking: EFERT/RT vaar betekenisvol beter as EFERT in die beoordeling van twyfelagtige letsels op planare beenflikkergramme. Daar is geen bewys dat die voordeel van EFERT/RT afhanklik is van die tipe primêre tumor of die teenwoordigheid van beenpyn nie. Waar hulpbronne beperk is, is EFERT/RT slegs aangedui in dié pasiënte waar verwag word dat korrekte klassifikasie van die betrokke letsel behandeling sal beïnvloed. EFERT/RT beelde behoort met die hulp van ‘n diagnostiese radioloog beoordeel te word, of kerngeneeskundiges moet genoegsame ondervinding in die interpretasie van rekenaartomografiebeelde hê om die diagnostiese voordeel van EFERT/RT optimaal te kan benut.