Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging

X-ray fluoroscopy-guided  endovascular procedures have several significant limitations, including  difficult catheter navigation and use of ionizing ...

University of California, San Francisco 

In order to improve the safety and efficacy of percutaneous aortic valve replacement procedures, a closed bore hybrid x-ray/MRI (CBXMR) system is proposed in which an x-ray C-arm will be positioned with its isocenter approximately =1 m from the entrance of a clinical MRI scanner. This system will harness the complementary strengths of both modalities to improve clinical outcome. A key component of the CBXMR system will be a rotating anode x-ray tube to produce high-quality x-ray images. There are challenges in positioning an x-ray tube in the magnetic fringe field of the MRI magnet. Here, the effects of an external magnetic field on x-ray tube induction motors of radiography x-ray tubes and the corresponding reduction of x-ray tube heat loadability are investigated. Anode rotation frequency f(aode) was unaffected when the external magnetic field Bb was parallel to the axis of rotation of the anode but decreased when Bb was perpendicular to the axis of rotation. The experimental f(anode) values agreed with predicted values to within +/-3% over a Bb range of 0-30 mT. The MRI fringe field at the proposed location of the x-ray tube mounted on the C-arm (approximately =4 mT) reduced f(anode) by only 1%, so x-ray tube heat loadability will not be compromised when using CBXMR systems for percutaneous aortic valve replacement procedures. Eddy current heating power in the rotor due to an MRI fringe field was found to be two orders of magnitude weaker than the heating power produced on the anode due to a fluoroscopic exposure, so eddy current heating had no effect on x-ray tube heat loadability.

Closed bore XMR (CBXMR) systems for aortic valve replacement: investigation of rotating-anode x-ray tube heat loadability.

Afin d&#39;am&eacute;liorer la s&eacute;curit&eacute; et l&#39;efficacit&eacute; des proc&eacute;dures de remplacement valvulaire aortique percutan&eacute;, un syst&egrave;me de x-ray/IRM (CBXMR) al&eacute;sage ferm&eacute; hybride est propos&eacute; dans lequel se placera un radiographie C-bras avec ses isocenter environ = 1 m de l&#39;entr&eacute;e d&#39;un scanner MRI clinique. Ce syst&egrave;me exploitera les forces compl&eacute;mentaires des deux modalit&eacute;s d&#39;am&eacute;lioration des r&eacute;sultats cliniques. Un &eacute;l&eacute;ment cl&eacute; du syst&egrave;me CBXMR sera un tube &agrave; rayons x anode tournante pour produire des images de rayons x de haute qualit&eacute;. Il reste &agrave; positionner un tube &agrave; rayons x dans le domaine de la frange magn&eacute;tique de l&#39;aimant de MRI. Ici, les effets d&#39;un champ magn&eacute;tique externe sur les moteurs &agrave; induction &agrave; tube &agrave; rayons x des tubes &agrave; rayons x radiographie et la r&eacute;duction correspondante de la capacit&eacute; de charge du tube radiog&egrave;ne chaleur sont &eacute;tudi&eacute;s. Anode rotation f(aode) de fr&eacute;quence n&#39;est pas affect&eacute;e lorsque le champ magn&eacute;tique externe Bb &eacute;tait parall&egrave;le &agrave; l&#39;axe de rotation de l&#39;anode, mais diminue lorsque Bb est perpendiculaire &agrave; l&#39;axe de rotation. Les valeurs exp&eacute;rimentales de f(anode) d&#39;accord avec les valeurs pr&eacute;dites au sein de +/-3 % sur une gamme de Bb de 0-30 Mt. Le champ de frange de MRI &agrave; l&#39;emplacement pr&eacute;vu du tube radiog&egrave;ne mont&eacute; sur le C-bras (environ = mT 4) r&eacute;duite des f(anode) de seulement 1 %, et capacit&eacute; de charge du tube radiog&egrave;ne chaleur ne sera pas compromise lors de l&#39;utilisation de syst&egrave;mes de CBXMR pour les proc&eacute;dures de remplacement valvulaire aortique percutan&eacute;. Eddy actuel courant dans le rotor en raison d&#39;un champ de frange de MRI de chauffage s&#39;est av&eacute;r&eacute; pour &ecirc;tre de deux ordres de grandeur plus faibles que la puissance de chauffage produite sur l&#39;anode due &agrave; une exposition fluoroscopique, donc chauffage courant de Foucault n&#39;avait aucun effet sur la capacit&eacute; de charge thermique du tube radiog&egrave;ne.

Syst&egrave;mes XMR (CBXMR) al&eacute;sage ferm&eacute;e pour un remplacement valvulaire aortique : enqu&ecirc;te de capacit&eacute; de charge chaleur tournante-anode du tube radiog&egrave;ne.

A hybrid closed-bore x-ray/MRI system (CBXMR) is proposed to improve the safety and efficacy of percutaneous aortic valve replacement procedures. In this system, an x-ray C-arm will be positioned about 1 m from the entrance of a 1.5 T MRI scanner. The CBXMR system will harness the complementary strengths of both modalities to guide and deploy a bioprosthetic valve into the aortic annulus of the heart without coronary artery obstruction. A major challenge in constructing this system is ensuring proper operation of a rotating-anode x-ray tube in the MRI magnetic fringe field environment. The electron beam in the x-ray tube responsible for producing x rays can be deflected by the fringe field. However, the clinical impact of electron beam deflection in a magnetic field has not yet been studied. Here, the authors investigated changes in focal spot resolving power, field of view shift, and field of view truncation in x-ray images as a result of electron beam deflection. The authors found that in the fringe field acting on the x-ray tube at the clinical location for the x-ray C-arm (4 mT), focal spot size increased by only 2%, so the fringe field did not limit the resolving power of the x-ray system. The magnetic field also caused the field of view to shift by 3 mm. This shift must be corrected to avoid unnecessary primary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. The fringe field was too weak to cause field of view truncation.

Closed-bore XMR (CBXMR) systems for aortic valve replacement: x-ray tube imaging performance.

Un syst&egrave;me hybride de x-ray/IRM ferm&eacute;-al&eacute;sage (CBXMR) est propos&eacute; pour am&eacute;liorer la s&eacute;curit&eacute; et l&#39;efficacit&eacute; des proc&eacute;dures de remplacement valvulaire aortique percutan&eacute;. Dans ce syst&egrave;me, un rayon x C-bras sera positionn&eacute; environ 1 m de l&#39;entr&eacute;e d&#39;un scanner IRM T 1,5. Le syst&egrave;me CBXMR exploitera les forces compl&eacute;mentaires des deux modalit&eacute;s de guider et de d&eacute;ployer une valve BIOPROTH&Eacute;TIQUE dans l&#39;anneau aortique du coeur sans obstruction de l&#39;art&egrave;re coronaire. Un d&eacute;fi majeur dans la construction de ce syst&egrave;me est d&#39;assurer un fonctionnement correct d&#39;un tube &agrave; rayons x tournant-anode dans le milieu de terrain de frange magn&eacute;tique MRI. Le faisceau d&#39;&eacute;lectrons dans le tube radiog&egrave;ne, responsable de la production de rayons x peut &ecirc;tre d&eacute;vi&eacute; par le champ de la frange. Toutefois, l&#39;impact clinique de la d&eacute;viation de faisceau &eacute;lectrons dans un champ magn&eacute;tique n&#39;a pas encore &eacute;t&eacute; &eacute;tudi&eacute;e. Ici, les auteurs ont &eacute;tudi&eacute; les changements dans le pouvoir de r&eacute;solution spot focal, champ de vue Maj et troncature de champ en images aux rayons x en raison de la d&eacute;viation du faisceau &eacute;lectronique. Les auteurs ont constat&eacute; que, dans le domaine de la frange agissant sur le tube &agrave; rayons x &agrave; l&#39;endroit de clinique pour les rayons x C-bras (4 mT), taille de tache focale a augment&eacute; de seulement 2 %, donc le domaine de la frange ne limite pas le pouvoir de r&eacute;solution du syst&egrave;me x-ray. Le champ magn&eacute;tique provoqu&eacute; &eacute;galement le champ de vision de passer de 3 mm. Ce changement doit &ecirc;tre corrig&eacute; pour &eacute;viter l&#39;exposition au rayonnement primaire inutile pour le patient et le personnel dans le laboratoire de cath&eacute;t&eacute;risme cardiaque. Le domaine de la frange &eacute;tait trop faible pour causer la troncature du champ de vision.

Ferm&eacute;-al&eacute;sage syst&egrave;mes XMR (CBXMR) pour un remplacement valvulaire aortique : tube &agrave; rayons x performance d&#39;imagerie.

Per migliorare la sicurezza e l&#39;efficacia delle procedure di sostituzione valvola aortica percutanea &egrave; proposto un sistema ibrido x-ray/MRI a foro chiuso (CBXMR). In questo sistema, un braccio a C radiografia verr&agrave; posizionato circa 1 m dall&#39;ingresso di uno scanner MRI T 1.5. Il sistema CBXMR si sfruttano le forze complementari di entrambe le modalit&agrave; di guida e distribuire una valvola di bioprotesici nell&#39;anulus dell&#39;aorta del cuore senza ostruzione delle arterie coronarie. Una sfida importante nella costruzione di questo sistema &egrave; garantire il corretto funzionamento di un tubo di raggi x di anodo rotante nell&#39;ambiente di campo magnetico frangia MRI. Il fascio di elettroni nel tubo a raggi x responsabile per la produzione di raggi x pu&ograve; essere deviato dal campo frangia. Tuttavia, l&#39;impatto clinico di deflessione di fascio di elettroni in un campo magnetico non &egrave; ancora stato studiato. Qui, gli autori hanno indagato cambiamenti nel potere risolvente spot focale, campo di vista MAIUSC e troncamento del campo di vista nelle immagini a raggi x in seguito a deflessione di fascio di elettroni. Gli autori che ha trovato nel campo frangia agendo sul tubo a raggi x presso il percorso clinico per il braccio a C a raggi x (4 mT), dimensione spot focale aumentato di solo il 2%, quindi il campo di fringe non ha limitato il potere risolvente del sistema a raggi x. Il campo magnetico ha causato anche il campo di vista per lo spostamento di 3 mm. Questo spostamento deve essere corretta per evitare l&#39;esposizione a radiazioni primarie inutili per il paziente e il personale del laboratorio di cateterismo cardiaco. Il campo di frangia era troppo debole per causare il troncamento del campo di vista.

Chiuso-foro sistemi XMR (CBXMR) per la sostituzione della valvola aortica: tubo a raggi x prestazioni di imaging.

Se propone un sistema h&iacute;brido de x-ray/MRI agujero cerrado (CBXMR) para mejorar la seguridad y eficacia de los procedimientos de reemplazo de v&aacute;lvula a&oacute;rtica percut&aacute;nea. En este sistema, se colocar&aacute; un rayos x C-arm cerca de 1 m de la entrada de un 1.5 T resonancia. El sistema CBXMR potenciar&aacute; la complementariedad y fortalezas de ambas modalidades para guiar y desplegar una v&aacute;lvula bioprot&eacute;sicos dentro del anillo a&oacute;rtico del coraz&oacute;n sin obstrucci&oacute;n de la arteria coronaria. Un reto importante en la construcci&oacute;n de este sistema es garantizar el funcionamiento de un tubo de rayos x de &aacute;nodo giratorio en el entorno de campo magn&eacute;tico de la franja de MRI. El haz de electrones en el tubo de rayos x, responsable de producir rayos x puede ser desviado por el campo de la franja. Sin embargo, la repercusi&oacute;n cl&iacute;nica de la desviaci&oacute;n de viga del electr&oacute;n en un campo magn&eacute;tico todav&iacute;a no ha estudiado. Aqu&iacute;, los autores investigaron cambios en poder de resoluci&oacute;n punto focal, cambio de campo de visi&oacute;n y campo de visi&oacute;n truncamiento en radiograf&iacute;as como resultado de la desviaci&oacute;n de viga del electr&oacute;n. Los autores encontraron que en el campo de la franja en el tubo de rayos x en la situaci&oacute;n cl&iacute;nica para los rayos x C-arm (mT 4), tama&ntilde;o de punto focal aument&oacute; solamente 2%, por lo que el campo de la franja no limit&oacute; el poder de resoluci&oacute;n del sistema de rayos x. El campo magn&eacute;tico causado tambi&eacute;n el campo de visi&oacute;n por mm 3. Este cambio debe ser corregido para evitar la exposici&oacute;n a la radiaci&oacute;n primaria innecesarias para el paciente y el personal en el laboratorio de cateterismo card&iacute;aco. El campo de la franja era demasiado d&eacute;bil para causar el truncamiento del campo de visi&oacute;n.

Calibre cerrado sistemas XMR (CBXMR) para el reemplazo de la v&aacute;lvula a&oacute;rtica: rendimiento de la proyecci&oacute;n de imagen de tubo de rayos x.

Hybrid closed bore x-ray/MRI systems are being developed to improve the safety and efficacy of percutaneous aortic valve replacement procedures by harnessing the complementary strengths of the x-ray and MRI modalities in a single interventional suite without requiring patient transfer between two rooms. These systems are composed of an x-ray C-arm in close proximity (approximately 1 m) to an MRI scanner. The MRI magnetic fringe field can cause the electron beam in the x-ray tube to deflect. The deflection causes the x-ray field of view to shift position on the detector receptacle. This could result in unnecessary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. Therefore, the electron beam deflection must be corrected. The authors developed an active magnetic shielding system that can correct for electron beam deflection to within an accuracy of 5% without truncating the field of view or increasing exposure to the patient. This system was able to automatically adjust to different field strengths as the external magnetic field acting on the x-ray tube was changed. Although a small torque was observed on the shielding coils of the active shielding system when they were placed in a magnetic field, this torque will not impact their performance if they are securely mounted on the x-ray tube and the C-arm. The heating of the coils of the shielding system for use in the clinic caused by electric current was found to be slow enough not to require a dedicated cooling system for one percutaneous aortic valve replacement procedure. However, a cooling system will be required if multiple procedures are performed in one session.

Closed bore XMR (CBXMR) systems for aortic valve replacement: active magnetic shielding of x-ray tubes.

Hybride ferm&eacute; al&eacute;sage x-ray/MRI syst&egrave;mes sont d&eacute;velopp&eacute;s pour am&eacute;liorer la s&eacute;curit&eacute; et l&#39;efficacit&eacute; des proc&eacute;dures de remplacement valvulaire aortique percutan&eacute; en exploitant les forces compl&eacute;mentaires des rayons x et des modalit&eacute;s de MRI dans une suite d&#39;intervention unique sans n&eacute;cessiter le transfert des patients entre les deux chambres. Ces syst&egrave;mes se composent d&#39;un C-bras de rayons x &agrave; proximit&eacute; (environ 1 m) pour un scanner de MRI. Le champ magn&eacute;tique de frange de MRI peut causer le faisceau d&#39;&eacute;lectrons dans le tube &agrave; rayons x pour faire d&eacute;vier. La d&eacute;viation provoque le champ de vision aux rayons x, &agrave; changer de position sur l&#39;embase du d&eacute;tecteur. Cela pourrait entra&icirc;ner une exposition aux radiations inutiles pour le patient et le personnel dans le laboratoire de cath&eacute;t&eacute;risme cardiaque. Par cons&eacute;quent, la d&eacute;viation de faisceau d&#39;&eacute;lectrons doit &ecirc;tre corrig&eacute;e. Les auteurs ont mis au point un syst&egrave;me de blindage magn&eacute;tique actif qui permet de corriger pour la d&eacute;viation de faisceau &eacute;lectronique pour une pr&eacute;cision de 5 % sans tronquer le champ de vision ou d&#39;augmentation de l&#39;exposition du patient. Ce syst&egrave;me &eacute;tait capable de s&#39;adapter automatiquement &agrave; l&#39;intensit&eacute; des champs diff&eacute;rents comme le champ magn&eacute;tique agissant sur le tube &agrave; rayons x a &eacute;t&eacute; chang&eacute;. Bien qu&#39;un petit couple a &eacute;t&eacute; observ&eacute; sur les bobines de blindage du syst&egrave;me de blindage actif lorsqu&#39;ils ont &eacute;t&eacute; plac&eacute;s dans un champ magn&eacute;tique, ce couple n&#39;affectera pas leurs performances si elles sont solidement mont&eacute;s sur le tube &agrave; rayons x et le C-bras. Le chauffage des bobines du syst&egrave;me de blindage pour utilisation dans la clinique provoqu&eacute;e par le courant &eacute;lectrique s&#39;est av&eacute;r&eacute; pour &ecirc;tre assez lent ne pas d&#39;exiger un syst&egrave;me de refroidissement d&eacute;di&eacute; pour une proc&eacute;dure de remplacement valvulaire aortique percutan&eacute;. Toutefois, un syst&egrave;me de refroidissement sera requis si plusieurs proc&eacute;dures sont effectu&eacute;es en une seule session.

Syst&egrave;mes XMR (CBXMR) al&eacute;sage ferm&eacute;e pour un remplacement valvulaire aortique : blindage magn&eacute;tique actif de tubes &agrave; rayons x.

Ibrido chiuso Alesaggio x-ray/MRI sistemi vengono sviluppati per migliorare la sicurezza e l&#39;efficacia delle procedure di sostituzione percutanea valvola aortica sfruttando le forze complementari dei raggi x e modalit&agrave; MRI in un unica suite interventistica senza richiedere trasferimento paziente tra le due camere. Questi sistemi sono composti da un braccio a C radiografia nelle immediate vicinanze (circa 1 m) di uno scanner MRI. Il campo magnetico frangia MRI pu&ograve; causare il fascio di elettroni nel tubo a raggi x per deviare. La deformazione provoca a raggi x campo visivo a spostare di posizione sul recipiente rivelatore. Questo potrebbe provocare l&#39;inutile esposizione a radiazioni per il paziente e il personale del laboratorio di cateterismo cardiaco. Pertanto, deve essere corretta la deflessione del fascio di elettroni. Gli autori hanno sviluppato un sistema attivo di schermatura magnetico che pu&ograve; correggere per electron beam deflessione all&#39;interno di una precisione del 5% senza troncare il campo visivo o aumentare l&#39;esposizione al paziente. Questo sistema &egrave; stato in grado di regolare automaticamente a intensit&agrave; di campo differenti, come il campo magnetico esterno agendo sul tubo a raggi x &egrave; stato modificato. Anche se una piccola coppia &egrave; stata osservata su bobine di schermatura del sistema di schermatura attiva quando sono stati messi in un campo magnetico, questa coppia non avr&agrave; un impatto delle loro prestazioni se sono saldamente montati sul tubo a raggi x e la C-arm. Le bobine del sistema schermante per uso nella clinica causata dalla corrente elettrica, il riscaldamento &egrave; stato trovato per essere abbastanza lento per non richiedono un sistema di raffreddamento dedicato per una procedura di sostituzione della valvola aortica percutanea. Tuttavia, un sistema di raffreddamento sar&agrave; richiesto se pi&ugrave; procedure vengono eseguite in una sola sessione.

Foro chiuso XMR (CBXMR) sistemi per la sostituzione della valvola aortica: attivo schermatura magnetica di tubi a raggi x.

H&iacute;brido cerrado alesaje x-ray/MRI se est&aacute;n desarrollando sistemas para mejorar la seguridad y eficacia de los procedimientos de reemplazo de v&aacute;lvula a&oacute;rtica percut&aacute;nea aprovechando la complementariedad y fortalezas de la radiograf&iacute;a y modalidades de MRI en una &uacute;nica suite intervencionista sin necesidad de transferencia de pacientes entre dos habitaciones. Estos sistemas se componen de un rayos x C-arm cerca (aproximadamente 1 m) para un esc&aacute;ner de MRI. El campo magn&eacute;tico de la franja de MRI puede causar el haz de electrones en el tubo de rayos x para desviar. La desviaci&oacute;n hace que el campo de visi&oacute;n de rayos x cambiar de posici&oacute;n en el recept&aacute;culo del detector. Esto puede resultar en exposici&oacute;n a la radiaci&oacute;n innecesarias para el paciente y el personal en el laboratorio de cateterismo card&iacute;aco. Por lo tanto, debe corregirse la desviaci&oacute;n de viga del electr&oacute;n. Los autores desarrollaron un sistema activo de apantallamiento magn&eacute;tico que puede corregir para la desviaci&oacute;n de viga del electr&oacute;n a una precisi&oacute;n del 5% sin truncar el campo de visi&oacute;n o aumentar la exposici&oacute;n del paciente. Este sistema fue capaz de ajustar autom&aacute;ticamente a las intensidades de campo diferentes como el campo magn&eacute;tico externo act&uacute;a sobre el tubo de rayos x fue cambiado. Aunque un peque&ntilde;o esfuerzo de torsi&oacute;n se observ&oacute; en las bobinas de protecci&oacute;n del sistema de protecci&oacute;n activa cuando se colocaron en un campo magn&eacute;tico, este par no afectar&aacute; su rendimiento, si bien se montan en el tubo de rayos x y C-arm. El calentamiento de las bobinas del sistema de protecci&oacute;n para su uso en la cl&iacute;nica de la corriente el&eacute;ctrica fue encontrado para ser lo suficientemente lento como para no requieren un sistema de enfriamiento dedicado para un procedimiento de reemplazo de v&aacute;lvula a&oacute;rtica percut&aacute;nea. Sin embargo, un sistema de enfriamiento ser&aacute; necesario si se realizan varios procedimientos en una sola sesi&oacute;n.

Agujero cerrado XMR (CBXMR) sistemas de reemplazo valvular a&oacute;rtico: blindaje magn&eacute;tico activo de tubos de rayos x.

Combining x-ray fluoroscopy and MR imaging systems for guidance of interventional procedures has become more commonplace. By designing an x-ray tube that is immune to the magnetic fields outside of the MR bore, the two systems can be placed in close proximity to each other. A major obstacle to robust x-ray tube design is correcting for the effects of the magnetic fields on the x-ray tube focal spot. A potential solution is to design active shielding that locally cancels the magnetic fields near the focal spot.

Magnetostatic focal spot correction for x-ray tubes operating in strong magnetic fields using iterative optimization.

Combinant la radioscopie aux rayons x et M. formation image des syst&egrave;mes de guidage des proc&eacute;dures interventionnelles est devenu plus banal. En concevant un tube &agrave; rayons x qui est immunis&eacute; contre les champs magn&eacute;tiques &agrave; l&#39;ext&eacute;rieur de la MR d&#39;al&eacute;sage, les deux syst&egrave;mes peuvent &ecirc;tre plac&eacute;s &agrave; proximit&eacute; les uns aux autres. Un obstacle majeur &agrave; la conception robuste du tube radiog&egrave;ne est corrig&eacute; pour les effets des champs magn&eacute;tiques sur la foyer du tube radiog&egrave;ne. Une solution possible est de concevoir un blindage actif qui annule localement les champs magn&eacute;tiques pr&egrave;s du foyer.

Correction des taches focale magnetostatique pour tubes &agrave; rayons x dans des champs magn&eacute;tiques &agrave; l&#39;aide d&#39;optimisation it&eacute;rative.

Combinando la fluoroscopia a raggi x e MR imaging systems per l&#39;orientamento delle procedure interventistiche &egrave; diventata pi&ugrave; banale. Progettando un tubo a raggi x che &egrave; immune ai campi magnetici di fuori del signor alesaggio, i due sistemi possono essere collocati in prossimit&agrave; di ogni altro. Un ostacolo importante al design robusto tubo di raggi x &egrave; correggere per gli effetti dei campi magnetici sul posto focale tubo a raggi x. Una potenziale soluzione &egrave; di progettare schermatura attiva che localmente annulla i campi magnetici vicino il punto focale.

Magnetostatica correzione spot focale per tubi a raggi x che operano in campi magnetici forti tramite Ottimizzazione iterativa.

Utilizzando sistemi ibridi x-ray&#x2215;MR (XMR) per orientamento immagine durante le procedure interventistiche potrebbe migliorare la diagnosi e il trattamento di disturbi neurologici, oncologico, cardiovascolari e altri. Gli autori propongono un design di sistema ibrido di prossimit&agrave; in cui un apparecchio di fluoroscopia C-braccio sono posizionato immediatamente adiacente al magnete Solenoide di un signor sistema con una distanza minima di 1,2 m tra i raggi x e MR imaging campi di vista. Disegni di tubo a raggi x di anodo rotante esistenti falliscono entro Signor ambienti di frangia campo perch&eacute; i campi magnetici alterare le traiettorie degli elettroni nel tubo a raggi x e agire come un freno sul motore ad induzione, riducendo la velocit&agrave; di rotazione dell&#39;anodo. In questo studio gli autori propongono un design motore romanzo che evita la riduzione di velocit&agrave; di rotazione anodo.

Romanzo motore design per tubi a raggi x di anodo operante nel campo frangia di un sistema di imaging a risonanza magnetica di rotazione.

Using hybrid x-rayâˆ•MR (XMR) systems for image guidance during interventional procedures could enhance the diagnosis and treatment of neurologic, oncologic, cardiovascular, and other disorders. The authors propose a close proximity hybrid system design in which a C-arm fluoroscopy unit is placed immediately adjacent to the solenoid magnet of a MR system with a minimum distance of 1.2 m between the x-ray and MR imaging fields of view. Existing rotating anode x-ray tube designs fail within MR fringe field environments because the magnetic fields alter the electron trajectories in the x-ray tube and act as a brake on the induction motor, reducing the rotation speed of the anode. In this study the authors propose a novel motor design that avoids the anode rotation speed reduction.

Novel motor design for rotating anode x-ray tubes operating in the fringe field of a magnetic resonance imaging system.

&Agrave; l&#39;aide de syst&egrave;mes x-ray&#x2215;MR (XRM) hybrides pour le guidage par l&#39;image au cours de proc&eacute;dures interventionnelles pourrait am&eacute;liorer le diagnostic et le traitement des troubles neurologiques, oncologiques, cardiovasculaires ou autres. Les auteurs proposent une conception de syst&egrave;me hybride proximit&eacute; dans lequel un appareil de radioscopie C-bras est plac&eacute; juste &agrave; c&ocirc;t&eacute; de l&#39;aimant sol&eacute;no&iuml;de d&#39;un syst&egrave;me de Monsieur avec une distance minimale de 1,2 m entre les rayons x et M. imageries champs de vision. Conceptions existantes de tube &agrave; rayons x du anode tournante &eacute;chouent dans les environnements de domaine M. frange car les champs magn&eacute;tiques modifier les trajectoires des &eacute;lectrons dans le tube &agrave; rayons x et agir comme un frein sur le moteur &agrave; induction, r&eacute;duisant la vitesse de rotation de l&#39;anode. Dans cette &eacute;tude, les auteurs proposent une conception originale de moteur qui permet d&#39;&eacute;viter la r&eacute;duction de vitesse de rotation anode.

Nouvelle conception de moteur pour faire tourner les tubes &agrave; rayons x anode op&eacute;rant dans le domaine de la frange d&#39;un syst&egrave;me d&#39;imagerie par r&eacute;sonance magn&eacute;tique.

Prasheel Lillaney

Department of Radiology and Biomedical Imaging

University of California, San Francisco

Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging

Prasheel Lillaney

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Radiology and Biomedical Imaging

University of California, San Francisco

Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging

Department of Radiology and Biomedical Imaging