PROBLEM TO BE SOLVED: To provide a technique for securing a wide examination space without causing any increase in manufacturing costs and without largely lowering irradiation efficiency and uniformity of irradiation distribution in an imaging region in a tunnel type MRI apparatus.SOLUTION: The invention provides an RF coil unit in which four partial cylindrical coils are disposed at spaces in the peripheral direction two by two opposite to each other inside a cylindrical high-frequency shield, and magnetic fields generated by the individual partial cylindrical coils are composed to generate a circularly polarized or elliptically polarized magnetic field. Each of the partial cylindrical coils includes: a partial cylindrical conductor a plurality of first conductors substantially parallel to the central axis of the high-frequency shield a plurality of capacitors connecting both ends of each first conductor and the partial cylindrical conductor and a second conductor to which at least one end of the first conductor is adjacent. A high-frequency signal having an identical reference frequency, and a desired amplitude ratio and a phase difference is supplied to each partial cylindrical coil.COPYRIGHT: (C)2014,JPO&INPIT【課題】トンネル型MRI装置において、製造コストの増大を招くことなく、かつ、照射効率や撮影領域における照射分布の均一性を大きく低下させることなしに、広い検査空間を確保する技術を提供する。【解決手段】本発明は、筒状の高周波シールドの内側に4つの部分筒状コイルを2つずつ対向させて周方向に間隔をあけて配置し、個々の部分筒状コイルにより生成される磁場を合成することにより円偏波もしくは楕円偏波磁場を生成するRFコイルユニットを提供する。部分筒状コイルは、部分筒状導体と高周波シールドの中心軸と実質的に平行な複数の第一導体と各第一導体の両端と部分筒状導体を接続する複数のキャパシタと第一導体の少なくとも一方の端部を隣接する第二導体とを備える。各部分筒状コイルには、基準周波数は同一で、所望の振幅比および位相差を有する高周波信号をそれぞれ供給する。【選択図】図3
