{"id":13611,"date":"2020-10-06T16:38:49","date_gmt":"2020-10-06T13:38:49","guid":{"rendered":"https:\/\/umram.bilkent.edu.tr\/index.php\/2020\/10\/06\/doktora-mezuniyeti-ehsan-kazemivalipour\/"},"modified":"2026-11-04T11:02:42","modified_gmt":"2026-11-04T08:02:42","slug":"doktora-mezuniyeti-ehsan-kazemivalipour","status":"publish","type":"post","link":"https:\/\/umram.bilkent.edu.tr\/index.php\/tr\/2020\/10\/06\/doktora-mezuniyeti-ehsan-kazemivalipour\/","title":{"rendered":"Doktora mezuniyeti: Ehsan Kazemivalipour"},"content":{"rendered":"<p><a href=\"https:\/\/umram.bilkent.edu.tr\/index.php\/teams\/ehsan-kazemivalipour\/\">Ehsan Kazemivalipour<\/a>, \u201cInnovative Designs of RF Transmit Array Coils and RF Heating Analysis of Patients with Implanted DBS\u201d ba\u015fl\u0131kl\u0131 doktora tezini sunmu\u015ftur.<\/p>\n\n<p>\u00d6zet<\/p>\n<p>G\u00fcvenli ve verimli bir MRI incelemesi, uygun radyofrekans (RF) bobinlerinin bilin\u00e7li bi\u00e7imde tan\u0131mlanmas\u0131na, tasarlanmas\u0131na, \u00fcretilmesine, de\u011ferlendirilmesine ve uygulanmas\u0131na dayan\u0131r. Bu hedefler do\u011frultusunda tez, yeni RF iletim dizisi (TxArray) bobini tasar\u0131m tekniklerine \u00fc\u00e7 katk\u0131 ve derin beyin uyar\u0131m\u0131 (DBS) implantlar\u0131n\u0131n RF iletim bobinlerinde \u0131s\u0131nmas\u0131n\u0131n azalt\u0131lmas\u0131na iki katk\u0131 i\u00e7ermektedir.<\/p>\n<p>Birden fazla iletim eleman\u0131na sahip TxArray bobinleri, alan d\u00fczg\u00fcnl\u00fc\u011f\u00fcn\u00fc art\u0131rmak, \u00e7ekim s\u00fcresini k\u0131saltmak, \u00f6zg\u00fcl so\u011furma oran\u0131 (SAR) s\u0131cak noktalar\u0131n\u0131 azaltmaya \u00e7al\u0131\u015f\u0131rken RF \u015fimi yapmak ve g\u00fc\u00e7 verimlili\u011fini art\u0131rmak i\u00e7in kullan\u0131labilecek ek serbestlik dereceleri sa\u011flar. Bir TxArray bobininin nas\u0131l tasarland\u0131\u011f\u0131, paralel iletim teknolojisinden elde edece\u011fi kazanc\u0131 \u00f6nemli \u00f6l\u00e7\u00fcde etkiler. Bu nedenle tezin ilk katk\u0131s\u0131, TxArray bobinlerinin verimli \u00e7al\u0131\u015fma modlar\u0131n\u0131 elde etmek ve g\u00fc\u00e7 t\u00fcketimi a\u00e7\u0131s\u0131ndan verimli RF \u015fimi sa\u011flamak i\u00e7in sa\u00e7\u0131lma matrisinin \u00f6zmod analizidir. Algoritma 8 ile 32 kanal aras\u0131nda d\u00f6rt 3T TxArray bobininin tasar\u0131m\u0131nda denenmi\u015f ve yayg\u0131n tasar\u0131m tekniklerine g\u00f6re uyarma uzay\u0131n\u0131n boyutunu %50&#8217;ye kadar art\u0131rabildi\u011fi g\u00f6sterilmi\u015ftir. Bir sonraki katk\u0131, kusurlu \u00fcretilmi\u015f bir TxArray bobininin e\u015fde\u011fer devre modeli kullan\u0131larak hassas bi\u00e7imde ayarlanmas\u0131n\u0131 sa\u011flayan h\u0131zl\u0131 bir ince ayar y\u00f6ntemidir. \u00d6l\u00e7\u00fclen sa\u00e7\u0131lma parametreleri toplu bir devre modeline uydurularak 8 kanall\u0131 bir 3T TxArray bobininin t\u00fcm end\u00fcktans ve diren\u00e7leri kestirilmi\u015f ve \u00fcretilen bobin tek bir yinelemede uygun bi\u00e7imde ayarlanm\u0131\u015ft\u0131r. Ba\u015fka bir katk\u0131 olarak, bir TxArray bobininin kom\u015fu olmayan iletim kanallar\u0131 aras\u0131ndaki manyetik ba\u011fla\u015f\u0131m\u0131 en aza indirmek i\u00e7in kuramsal bir bobin boyutu eniyilemesi \u00f6nerilmi\u015ftir. 12 kanall\u0131 bir 3T TxArray bobininin t\u00fcm \u00f6z ve kar\u015f\u0131l\u0131kl\u0131 end\u00fcktanslar\u0131 hesaplan\u0131p kar\u015f\u0131l\u0131kl\u0131 end\u00fcktanslar en aza indirilerek boyutlar\u0131 belirlenmi\u015f ve yakla\u015f\u0131m\u0131n uygulanabilirli\u011fi sonlu elemanlar benzetimleriyle g\u00f6sterilmi\u015ftir.<\/p>\n<p>RF iletim bobinlerine ili\u015fkin g\u00fcvenlik konular\u0131ndan biri, metal implantlar\u0131n bobinin elektrik alanlar\u0131yla etkile\u015fimi nedeniyle SAR&#8217;\u0131n yerel olarak artmas\u0131d\u0131r. Bu nedenle d\u00f6rd\u00fcnc\u00fc katk\u0131, mekanik olarak d\u00f6nd\u00fcr\u00fclen do\u011frusal kutuplu bir ku\u015f kafesi rezonat\u00f6r\u00fc kullanan, hastaya g\u00f6re ayarlanabilir bir 3T iletim bobiniyle hastalardan elde edilmi\u015f ger\u00e7ek\u00e7i DBS implantlar\u0131n\u0131n u\u00e7lar\u0131ndaki SAR azaltma ba\u015far\u0131m\u0131n\u0131n de\u011ferlendirilmesidir. Yeniden yap\u0131land\u0131r\u0131labilir bobin sistemi, geleneksel d\u00f6rd\u00fcn ku\u015f kafesi bobinine g\u00f6re SAR&#8217;\u0131 tek tarafl\u0131 elektrotlarda ortalama %83, \u00e7ift tarafl\u0131 elektrotlarda ise %59 azaltmaktad\u0131r. Son \u00e7al\u0131\u015fmada, ger\u00e7ek\u00e7i elektrot y\u00f6r\u00fcngelerine sahip geni\u015f bir DBS implant\u0131 grubunun u\u00e7lar\u0131 \u00e7evresindeki yerel SAR art\u0131\u015f\u0131, ticari olarak sunulan dikey a\u00e7\u0131k t\u00fcnelli 1,2T bir bobinde ve standart yatay kapal\u0131 t\u00fcnelli 1,5T ku\u015f kafesi bobininde incelenmi\u015ftir. 1,2T dikey bobinde SAR, 1,5T yatay bobine g\u00f6re ortalama 31 kat azalmaktad\u0131r.<\/p>\n<p>Genel olarak tez, TxArray bobini tasar\u0131m\u0131 ile DBS hastalar\u0131nda \u0131s\u0131nman\u0131n de\u011ferlendirilmesi ve SAR&#8217;\u0131n azalt\u0131lmas\u0131 i\u00e7in yenilik\u00e7i yakla\u015f\u0131mlar \u00f6nermekte ve RF iletim bobinlerinin g\u00fc\u00e7 verimlili\u011fi ve hasta g\u00fcvenli\u011fi a\u00e7\u0131s\u0131ndan ba\u015far\u0131m\u0131n\u0131n art\u0131r\u0131lmas\u0131na katk\u0131 sa\u011flamaktad\u0131r.<\/p>\n\n","protected":false},"excerpt":{"rendered":"<p>Ehsan Kazemivalipour, \u201cInnovative Designs of RF Transmit Array Coils and RF Heating Analysis of Patients with Implanted DBS\u201d ba\u015fl\u0131kl\u0131 doktora tezini sunmu\u015ftur. \u00d6zet G\u00fcvenli ve verimli bir MRI incelemesi, uygun radyofrekans (RF) bobinlerinin bilin\u00e7li bi\u00e7imde tan\u0131mlanmas\u0131na, tasarlanmas\u0131na, \u00fcretilmesine, de\u011ferlendirilmesine ve uygulanmas\u0131na dayan\u0131r. Bu hedefler do\u011frultusunda tez, yeni RF iletim dizisi (TxArray) bobini tasar\u0131m tekniklerine \u00fc\u00e7\u2026<\/p>\n","protected":false},"author":9,"featured_media":11156,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[445,754],"tags":[],"class_list":["post-13611","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-duyurular","category-tez-sunumlari"],"_links":{"self":[{"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/posts\/13611","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/comments?post=13611"}],"version-history":[{"count":1,"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/posts\/13611\/revisions"}],"predecessor-version":[{"id":13612,"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/posts\/13611\/revisions\/13612"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/media\/11156"}],"wp:attachment":[{"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/media?parent=13611"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/categories?post=13611"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/umram.bilkent.edu.tr\/index.php\/wp-json\/wp\/v2\/tags?post=13611"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}