High sensitivity and good homogeneity are two major importance in RF coil design. Emphasis, however, should be placed on the improvement of sensitivity since it determines the signal-to-noise ratio which ultimately affects the resolution of image and imaging time. Homogeneity is mainly related to the image distortion and it is determined by the shapes and sizes of coil employed.
In order to improve the sensitivity of the NMR RF coil, the parameters determining the signal-to-noise ratio of RF coil are analyzed. Sensitivity improvement can be achieved by either increasing B1 field or decreasing resistance of the RF coil. Characteristics of copper foil and tube as conducting wire on a coil are studied in terms of skin effect at high frequency. It is also shown that balanced mode matching can be used for the sensitivity improvement by increase of number of turns in RF coil and achieved sensitivity gain experimentally observed reached as much as a factor two. This major sensitivity improvement is theoretically analyzed and experimented results are presented.
핵자기 공명 단층 촬영에서 빠른 시간에 좋은 질의 영상을 얻는 것은 매우 중요하다. 이를 위해서 고감도 고주파 코일이 요구되는데, 감도를 향상시키기 위하여 코일 전선으로 사용되는 구리 튜브와 스트립의 전기적 특성을 비교 분석하였으며 기존의 임피던스 정합회로 대신에 평형 정합회로를 제시하여 코일의 권선수를 증가시켜 고감도 고주파코일을 설계 제작하였고 이를 실제 실험적으로 입증하였다.
