京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18878号 / 医博第3989号 / 新制||医||1008(附属図書館) / 31829 / 京都大学大学院医学研究科医学専攻 / (主査)教授 坂井 義治, 教授 坂田 隆造, 教授 平岡 眞寛 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13540号 / 論医博第2280号 / 新制||医||1066(附属図書館) / (主査)教授 小濱 和貴, 教授 近藤 尚己, 教授 妹尾 浩 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Thesis (M. Tech. (Diagnostic Radiography)) Central University of Technology, Free State, 2014 / Over the past two decades, interventional radiology has been a fast developing field with great advances in technology in the diagnosing and treatment of patients. Interventional radiology procedures are minimally invasive and require little to no hospitalisation time. These procedures are fluoroscopically guided and serial runs are used for documentation, so they have the potential to deliver high doses to patients. Reports about deterministic skin reactions resulting from interventional radiology have become more and more prevalent from the early 1990s. Worldwide concern thus led to legislation for the limitation, justification and optimisation of these doses. Setting of diagnostic reference levels (DRLs) for these procedures is difficult, as they can be complex in nature and are often clinically open-ended. In the case where DRLs were used, they needed to be for a specific locality and had to be refined for the specific circumstances. Patients must be informed of the doses they will be receiving during diagnostic or interventional procedures before consent can be obtained from them. Little information on dose audits was available for South Africa at the time of the study, and it was decided to determine dose ranges at a local level. The research question of this study was: “What radiation doses do patients receive when undergoing vascular, diagnostic and interventional procedures in the interventional suites at a tertiary training hospital in the Free State?” The primary objective was to determine the doses and dose ranges to patients. A secondary objective was to identify specific high dose procedures to individual patients and to the population. A third objective was to investigate the factors influencing these doses. The data of patients who received procedures in two fluoroscopic rooms at the research site were documented over a three-year period. The dose area product (DAP) values were used to calculate skin dose. With the information gathered, dose ranges for frequently performed procedures were determined and specific high dose procedures to individuals and the population identified. Factors influencing the dose were also investigated. This included the relationship of the level of technology, a VI patient’s BMI and practitioners’ level of experience on dose as the research site was a training facility. The results indicated that both diagnostic and interventional procedures have the potential to deliver high doses, as was evident with the isolated occurrences where the response threshold for deterministic effects was exceeded. Most of the locally performed procedures delivered lower or on par radiation dose, compared to values in the literature. Increased BMI values of patients can negatively influence doses received. The level of a practitioner’s experience also plays a vital role in the dose that the patient will receive. Specific recommendations and the implementing of a dose optimisation protocol are proposed to reduce and optimise doses at the research site. This dose optimisation programme will create greater awareness about radiation dose and effects, follow-up procedures and dose reduction methods amongst role-payers. Key words: interventional radiology; limitation, justification and optimisation of radiation dose; deterministic effects; radiation dose awareness

Les ablations thermiques percutanées guidées par IRM sont actuellement contrôlées en temps réel grâce à la thermométrie IRM. Cependant, aucune information directement associée aux changement de propriétés intrinsèques du tissu n’est disponible pendant la procédure. Ces travaux offrent la possibilité d’un monitorage plus complet des ablations thermiques grâce à l’Elastographie par Résonance Magnétique (ERM) combinée à la thermométrie IRM. Le système proposé est composé d’un excitateur à aiguille, d’une séquence d’encodage du mouvement synchronisée sur la respiration et d’une méthode de reconstruction en temps réel de carte d’élasticité et de température. Les changements d’élasticité et de température se produisant lors d’ablations thermiques par laser ont été mesurés in vivo en temps réel avec succès grâce à ce système. Une nouvelle méthode de traitement des données ERM sans reconstruction d’images de phase est aussi proposée afin de s'affranchir d'étapes conventionnelles fastidieuses. / MR-guided percutaneous thermal ablations are currently monitored by MR thermometry. However, no information related to intrinsic property changes of the tissue is available during the procedure. The feasibility of monitoring in vivo thermal ablations by simultaneous Magnetic Resonance Elastography (MRE) and MR-thermometry is demonstrated in this work. The interventional MRE system includes a needle MRE driver, a respiratory triggered gradient-echo sequence with motion encoding, and an online reconstruction method that provides elasticity and temperature measurements in real-time. Changes in elasticity and temperature occurring during laser thermal ablations were successfully measured in vivo thanks to this interventional MRE system. An innovative method for MRE data processing without phase image reconstruction is also proposed in order to avoid challenging steps of the conventional process.

As fístulas arteriovenosas da região do seio cavernoso constituem as fístulas carotidocavernosas que podem ser diretas ou indiretas. As indiretas são raras, a sua sintomatologia é variada e o tratamento é controverso. Este estudo compreendeu a análise prospectiva de 44 pacientes portadores de fístulas carotidocavernosas indiretas (FCCI) no período de 01 de janeiro de 1994 e 31 de janeiro de 2004, 42 com etiologia espontânea e dois pacientes com etiologia traumática, sendo estes analisados separadamente. Doze (12) pacientes foram submetidos à conduta expectante e orientados a realizar manobras de compressão carótido-jugular. O tratamento endovascular foi realizado por via arterial, venosa ou combinação dos dois, num total de 30 pacientes. Considerando o grupo inteiro, ocorreu trombose espontânea em aproximadamente 24% dos pacientes. Os sintomas e o aspecto angiográfico após o tratamento evoluíram com melhora ou cura em 100% dos casos, com oclusão completa das FCCI em 63,3%, a grande maioria destes submetidos a apenas um procedimento. Além dos acessos venosos tradicionais aos seios cavernosos, vias de acesso alternativas através da veia oftálmica superior foram realizadas por punção percutânea de veia facial, veia supratroclear ou veia frontal. O material embolizante mais utilizado foi o adesivo tissular líquido, \"cola\", isoladamente ou em conjunto com outros materiais. Houve complicações transitórias em 13,3% dos pacientes tratados e nenhuma complicação permanente foi observada, o que demonstrou a baixa morbidade deste procedimento / The arteriovenous fistulas of the cavernous sinus (CS) region constitute the carotid-cavernous fistula, which can be direct or indirect. The indirect type is quite rare, its clinical features is very inespecific and its treatment modalities controversial. Forty-four patients with indirect carotid-cavernous fistulas (ICCF) were studied in a prospective manner between January 1994 to January 2004, 42 with spontaneous etiology and 2 with traumatic etiology, being these analyzed separately. Twelve (12) patients were submitted to a expectant management and instructed to perform carotid-jugular compression. Endovascular treatment was accomplished by arterial approach, vein approach or combination of both, in a total of 30 patients. Considering the entire group, spontaneous thrombosis was observed in approximately 24%. Symptoms and the angiographic features after endovascular treatment improved or disappeared in 100% of the cases, with total obliteration in 63.3%, most of them submitted to just one procedure. Despite the traditional venous routes to the CS, alternative accesses through the superior ophthalmic vein (SOV) were accomplished by percutaneous puncture of the facial, supratrochlear or frontal vein. Liquid adhesive (glue) was the most often embolic material used isolated or with other materials. No permanent complication was observed and only 13,3% of the patients treated cursed with transitory complications, what demonstrated the low morbidity of this procedure

INTRODUÇÃO: Durante procedimentos endovasculares, estão presentes os riscos relacionados ao uso dos contrastes iodados, tais como a nefropatia por contraste, uma vez que é fundamental o emprego de um meio de contraste para a obtenção das imagens radiológicas vasculares. A injeção intravascular de gás CO2 purificado é reconhecidamente uma alternativa relativamente mais segura ao contraste iodado, contudo, seu manuseio artesanal pode também trazer dificuldades técnicas e riscos aos pacientes. Para contemplar estas questões, foi desenvolvido o protótipo de um injetor intravascular de CO2 medicinal, microprocessado, dedicado à obtenção de imagens angiográficas. OBJETIVOS: Realizar os testes de viabilidade técnica inicial do protótipo em modelo in vivo. MÉTODOS: Realizar a angioplastia da artéria renal esquerda de 10 porcos, divididos em 2 grupos: Grupo 1 (n=5) injeção de contraste iodado, Grupo 2 (n=5) injeção de CO2 através do protótipo. Monitorização clínica e laboratorial dos animais no pré, intra e pós-operatório, com exames de função renal na véspera e 48h após os procedimentos e 3 gasometrias arteriais seriadas no intra-operatório. Observação clínica foi mantida por 48h no pós- operatório. RESULTADOS: Os procedimentos de angioplastia com CO2 foram realizados com sucesso técnico de 100%, sem necessidade de complementação com injeção de contraste iodado no Grupo 2. Não foram identificadas falhas no protótipo em funcionamento. Não foram identificadas alterações clínicas ou radiológicas sugestivas de contaminação por ar ambiente do sistema de CO2 e nem alterações laboratoriais nos animais. As imagens angiográficas obtidas no Grupo 2 foram consideradas, numa avaliação subjetiva, relativamente inferiores às imagens obtidas no Grupo 1. DISCUSSÃO: A qualidade inferior de imagem no Grupo 2 pode ser atribuída ao equipamento de fluoroscopia utilizado, com software desatualizado em relação aos equipamentos atuais, que incluem pré-configurações para angiografia com CO2; no entanto, ainda assim todos os procedimentos propostos no Grupo 2 foram realizados com sucesso técnico, o que nos leva a classificar as imagens deste grupo 2 como satisfatórias. O manuseio do aparelho mostrou-se ágil e eficiente, com a programação dos parâmetros sendo realizada com facilidade através do visor \"touch screen\", comparativamente superior ao método artesanal de injeção de CO2 com seringas em selo d\'água. CONCLUSÕES: O protótipo do aparelho injetor intravascular de CO2 funcionou de forma adequada durante os testes e as imagens obtidas permitiram a compleição com sucesso dos procedimentos. Portanto, os resultados positivos obtidos sugerem que o equipamento é tecnicamente viável / INTRODUCTION: During endovascular procedures, several risks related to iodinated contrast media are taken, such as Contrast Induced Nephropathy, since these are fundamental to obtain radiological vascular images under fluoroscopy. Intravascular medical grade CO2 injection is a widely accepted and relatively safer alternative to iodinated contrast, but its handling and manual delivery system could as well bring risks to patients, such as room air injection. To address these problems, we developed a prototype for a micro processed intravascular medicinal CO2 injector, dedicated to help obtain angiographic images. OBJECTIVES: To perform the in vivo Early Feasibility Clinical Studies of the prototype. METHODS: Perform a left renal artery angioplasty of 10 pigs, divided in 2 groups: Group 1 (n=5) injection of iodinated contrast and Group 2 (n=5) injection of CO2 with the prototype. Clinical and laboratorial data were measured pre, peri and post-operatively, by pre-operative and 48h post- operative creatinine tests and 3 peri-operative serial arterial blood gas analysis. Animais were kept under clinical observation for 48h after procedures. RESUL TS: Angioplasty procedures had 100% technical success in both groups, without the need of extra imaging with iodinated contrast in Group 2. There were no technical failures with the prototype. There were no identifiable clinical or radiological signs of room air intravascular injections. Ali laboratorial measurements were under normal value ranges. Angiography images obtained in Group 2 were subjectively considered inferior to images from Group 1. DISCUSSION: The inferior image quality in Group 2 could be attributed to the employed fluoroscopy equipment, since its software is not up to date to current equipment, which includes a dedicated CO2 angiography preset. Nevertheless, ali procedures in Group 2 were successful, and images in this group were therefore considered satisfactory. Handling of the prototype proved to be user friendly, since ali injection parameters are performed through a touch screen panel, much superior from previous authors experience with manual saline submerged syringe filling before intravascular injection. CONCLUSIONS: The intravascular CO2 injector prototype worked properly during the tests and the obtained images allowed successful procedures without unexpected complications, in consonance with previous positive in vitro results. Therefore, the study results suggest the positive early technical feasibility of the device

Finally, the system of vascular interventional radiology simulator is discussed by integrating all presented techniques and designing a trackball mouse based hardware sensors. Training experiments demonstrate that the presented techniques benefit rapid development of realistic and interactive vascular interventional radiology simulators. / Fourth, in order to clearly visualize vascular networks and the placement of instruments while treating the lesion, a physics-based simulation for angiography procedure is presented based on navier-stokes equation and semi-lagrangian method. The multi-scale vessel grid is reconstructed for flow distribution, and point sprites based rendering is adopted to preserve real-time visualization of the procedure. The experiments demonstrate that our results are more realistic compared to previous methods and are closer to the real angiography procedure. / In order to build a high fidelity interventional simulator for physician training and surgery planning, accurate reconstruction of three dimensional vascular network, real-time simulation of angiographic medium propagation and physics-based simulation of interaction between surgical instruments and vessel wall are absolutely indispensable. Thus, first, a methodology for geometric vascular modeling is proposed. As the reconstructed models are essential for many subsequent applications such as deformable modeling and visualization, a series of methods are proposed based on the parallel transport frames in order to maintain high mesh quality of these models. An improved bifurcation modeling method and two novel trifurcation modeling methods are developed based on 3D Bezier curve segments in order to ensure the continuous surface transition at furcations. To solve the twisting problem caused by frame mismatch of two successive furcations, a frame blending scheme is implemented. A curvature based adaptive sampling scheme combined with a mesh quality guided frame tilting algorithm is developed to construct an evenly distributed, non-concave and self-intersection free surface mesh. In terms of surface mesh quality criteria, our methodology can generate vascular models with better mesh quality than previous methods. / Second, we extend our geometric modeling method for illustrative visualization of vasculature, which is an indispensable component in medical education and training. Illustration of vasculature accentuates depth perception and provides a specific manner to identify the branching pattern and topology of vascular structure, which is crucial for therapy planning and real surgery in order to give an effective treatment. With advanced GPU acceleration techniques including render to texture (RTT) , framebuffer object (FBO) and fast image convolution, a real-time visualization can be achieved. / Third, an interactive simulation of angioplasty procedure is reported. To achieve an efficient modeling of soft tissue deformation and virtual device mechanics, mass spring models are adopted to construct the deformable models of vessel wall and stent. By designing a quasi-equilateral triangular mesh model of blood vessel and stent, a linear spring coefficients setting method is adopted to achieve the same accuracy compared with finite element method. With the employment of Physics Processing Unit (PPU), a real-time simulation of the interaction between blood vessel wall and surgical device is developed for vascular interventional radiology simulation. / Vascular diseases have been the leading cause of death worldwide. Interventional procedures are an increasingly promising therapy for treating vascular diseases, which are usually done by a guidewire-catheter combination under the fluoroscopic guidance. However, due to the complicated vascular network, bending of surgical instruments and the risk of vessel injury, these techniques need to be performed by highly trained and experienced specialists. Virtual reality based training of these procedures offers high flexibility and cost effective alternative. Furthermore, it allows training evaluation and accelerates learning process without risk to patients, therefore has distinct advantages than traditional training methods on animals or cadavers. / Guo, Jixiang. / Advisers: Pheng-Ann Heng; Tien-Tsin Wong. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 97-111). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

INTRODUÇÃO: Durante procedimentos endovasculares, estão presentes os riscos relacionados ao uso dos contrastes iodados, tais como a nefropatia por contraste, uma vez que é fundamental o emprego de um meio de contraste para a obtenção das imagens radiológicas vasculares. A injeção intravascular de gás CO2 purificado é reconhecidamente uma alternativa relativamente mais segura ao contraste iodado, contudo, seu manuseio artesanal pode também trazer dificuldades técnicas e riscos aos pacientes. Para contemplar estas questões, foi desenvolvido o protótipo de um injetor intravascular de CO2 medicinal, microprocessado, dedicado à obtenção de imagens angiográficas. OBJETIVOS: Realizar os testes de viabilidade técnica inicial do protótipo em modelo in vivo. MÉTODOS: Realizar a angioplastia da artéria renal esquerda de 10 porcos, divididos em 2 grupos: Grupo 1 (n=5) injeção de contraste iodado, Grupo 2 (n=5) injeção de CO2 através do protótipo. Monitorização clínica e laboratorial dos animais no pré, intra e pós-operatório, com exames de função renal na véspera e 48h após os procedimentos e 3 gasometrias arteriais seriadas no intra-operatório. Observação clínica foi mantida por 48h no pós- operatório. RESULTADOS: Os procedimentos de angioplastia com CO2 foram realizados com sucesso técnico de 100%, sem necessidade de complementação com injeção de contraste iodado no Grupo 2. Não foram identificadas falhas no protótipo em funcionamento. Não foram identificadas alterações clínicas ou radiológicas sugestivas de contaminação por ar ambiente do sistema de CO2 e nem alterações laboratoriais nos animais. As imagens angiográficas obtidas no Grupo 2 foram consideradas, numa avaliação subjetiva, relativamente inferiores às imagens obtidas no Grupo 1. DISCUSSÃO: A qualidade inferior de imagem no Grupo 2 pode ser atribuída ao equipamento de fluoroscopia utilizado, com software desatualizado em relação aos equipamentos atuais, que incluem pré-configurações para angiografia com CO2; no entanto, ainda assim todos os procedimentos propostos no Grupo 2 foram realizados com sucesso técnico, o que nos leva a classificar as imagens deste grupo 2 como satisfatórias. O manuseio do aparelho mostrou-se ágil e eficiente, com a programação dos parâmetros sendo realizada com facilidade através do visor \"touch screen\", comparativamente superior ao método artesanal de injeção de CO2 com seringas em selo d\'água. CONCLUSÕES: O protótipo do aparelho injetor intravascular de CO2 funcionou de forma adequada durante os testes e as imagens obtidas permitiram a compleição com sucesso dos procedimentos. Portanto, os resultados positivos obtidos sugerem que o equipamento é tecnicamente viável / INTRODUCTION: During endovascular procedures, several risks related to iodinated contrast media are taken, such as Contrast Induced Nephropathy, since these are fundamental to obtain radiological vascular images under fluoroscopy. Intravascular medical grade CO2 injection is a widely accepted and relatively safer alternative to iodinated contrast, but its handling and manual delivery system could as well bring risks to patients, such as room air injection. To address these problems, we developed a prototype for a micro processed intravascular medicinal CO2 injector, dedicated to help obtain angiographic images. OBJECTIVES: To perform the in vivo Early Feasibility Clinical Studies of the prototype. METHODS: Perform a left renal artery angioplasty of 10 pigs, divided in 2 groups: Group 1 (n=5) injection of iodinated contrast and Group 2 (n=5) injection of CO2 with the prototype. Clinical and laboratorial data were measured pre, peri and post-operatively, by pre-operative and 48h post- operative creatinine tests and 3 peri-operative serial arterial blood gas analysis. Animais were kept under clinical observation for 48h after procedures. RESUL TS: Angioplasty procedures had 100% technical success in both groups, without the need of extra imaging with iodinated contrast in Group 2. There were no technical failures with the prototype. There were no identifiable clinical or radiological signs of room air intravascular injections. Ali laboratorial measurements were under normal value ranges. Angiography images obtained in Group 2 were subjectively considered inferior to images from Group 1. DISCUSSION: The inferior image quality in Group 2 could be attributed to the employed fluoroscopy equipment, since its software is not up to date to current equipment, which includes a dedicated CO2 angiography preset. Nevertheless, ali procedures in Group 2 were successful, and images in this group were therefore considered satisfactory. Handling of the prototype proved to be user friendly, since ali injection parameters are performed through a touch screen panel, much superior from previous authors experience with manual saline submerged syringe filling before intravascular injection. CONCLUSIONS: The intravascular CO2 injector prototype worked properly during the tests and the obtained images allowed successful procedures without unexpected complications, in consonance with previous positive in vitro results. Therefore, the study results suggest the positive early technical feasibility of the device

Orientador: Diana Rodrigues Pina / Resumo: A Radiologia Intervencionista (RI) é a área da medicina que proporciona as maiores exposições ocupacionais. Os valores de dose aos quais os intervencionistas são expostos são difíceis de padronizar. Nesta pesquisa apresentamos uma avaliação completa das exposições ocupacionais e determinamos a eficiência de distintos métodos de dosimetria pessoal utilizados na RI. Essa pesquisa foi abordada em 2 etapas, conforme descrito a seguir: A primeira etapa se baseou em caracterizar as exposições ocupacionais em diferentes modalidades de procedimentos de RI vascular para duas categorias de profissionais e estimar o número de procedimentos anuais que cada profissional pode realizar sem exceder os limites de dose. Foi avaliada a exposição ocupacional, através de dosimetria termoluminescente, em diferentes partes do corpo (cristalino, tireoide, tórax, abdômen, pés e mãos) de duas categorias de intervencionistas (principais e assistentes) em três modalidades diferentes de procedimentos de RI vascular. As maiores doses equivalentes foram encontradas para as mão de ambos os profissionais, podendo chegar a aproximadamente 9 mSv em um único procedimento. Algumas regiões dos profissionais em alguns procedimentos podem receber, durante o ano, níveis de doses perigosamente perto dos limites anuais. Dosímetros posicionados no tórax podem subestimar as doses para outras regiões do corpo, especialmente abdômen, extremidades e cristalinos. Na segunda etapa foram avaliadas as eficiências de 6 diferent... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Interventional Radiology (IR) is the area of medicine that provides the largest occupational exposures. The dose values to which interventionists are exposed are difficult to standardize. In this research we present a complete evaluation of occupational exposures and determine the efficiency of different personal dosimetry methods used in IR. This research was performed in 2 stages, as described below: The first step was to characterize the occupational exposures in different modalities of vascular IR procedures for two categories of professionals. We also estimated the number of annual procedures that each professional can perform without exceeding the dose limits. Occupational exposures were evaluated in different body parts (crystalline, thyroid, thorax, abdomen, feet and hands) by two interventional categories (primary and assistants) in three different modalities of vascular IR procedures. The highest equivalent doses were found for the hands of both professionals, reaching approximately 9 mSv in a single procedure. Some regions of professionals in some procedures may receive dose levels during the year dangerously close to annual limits. Dosimeters positioned in the chest may underestimate the doses to other regions of the body, especially the abdomen, extremities and crystalline. The second stage, we evaluated the efficiencies of 6 different personal dosimetry methodologies used internationally to estimate the effective dose received by interventional professionals. An... (Complete abstract click electronic access below) / Mestre

Initiée dans les années 1960, la radiologie interventionnelle comprend les actes médicaux invasifs ayant pour but le traitement ou le diagnostic d’une pathologie réalisés sous guidage ou sous contrôle d’un moyen d’imagerie. L’enjeu de la thèse est de développer l’analyse sociohistorique de l’émergence d’une spécialité médicale – la radiologie interventionnelle – et d’en étudier les stratégies de légitimation. Trois axes d’investigation interdépendants sont plus particulièrement privilégiés. Le premier d’entre eux vise à comprendre comment est née cette pratique médicale en établissant l’archéologie des innovations dont elle résulte. Dans le deuxième, il s’agit d’analyser les stratégies de valorisation et les modes de faire-valoir de la radiologie interventionnelle. Les velléités d’autonomisation des radiologues interventionnels les ont ainsi conduits à mobiliser différents registres de légitimité (légitimité scientifique, légitimité professionnelle dans le champ médical, légitimité régulatoire). Le troisième axe permet quant à lui la prise en compte de la question de la démarcation sociale et des frontières. Étant porteuse d’une transgression de la dichotomie établie entre sphères diagnostique et thérapeutique, la radiologie interventionnelle a de fait entraîné une reconfiguration des relations entre spécialités. L’investigation s’appuie sur une méthodologie plurielle combinant entretiens semidirectifs, observations in situ (bloc opératoire, scanner, réunions de concertation pluridisciplinaire, consultations) et exploitation de données scientométriques. Une mise en perspective internationale avec la situation canadienne permet d’étudier l’impact des contextes nationaux sur la diffusion et la reconnaissance de la radiologie interventionnelle. / Introduced in the 1960s, interventional radiology includes invasive medical procedures for the treatment or diagnosis of a pathology performed under the guidance or control of an imaging device. The aim of the thesis is to develop the sociohistorical analysis of the emergence of a medical specialty – interventional radiology – and to study its legitimization strategies. Three interdependent lines of inquiry are privileged in particular. The first aims to understand how this medical practice was born by establishing the archaeology of the innovations that gave rise to it. In the second, it is a question of analyzing the strategies of valorization and the ways of valuing interventional radiology. The interventional radiologists’ desire for independence has led them to mobilize different registers of legitimacy (scientific legitimacy, professional legitimacy in the medical field, regulatory legitimacy). The third line of inquiry allows for the issue of social demarcation and boundaries to be taken into account. As it is a means of transgressing the established dichotomy between the diagnostic and therapeutic spheres, interventional radiology has in fact led to a reconfiguration of the relations between specialties. The investigation is based on a methodology combining semi-directive interviews, in situ observations (operating theater, multidisciplinary consultation meetings, consultations) and the use of scientometric data. An international perspective on the Canadian situation makes it possible to study the impact of national contexts on the dissemination and recognition of interventional radiology.