| 摘要 |
PURPOSE:To decrease bad influence of vibrating magnetic field and to improve an image quality by setting the interval of pulse sequences to a prescribed value corresponding to the frequency of an external vibrating magnetic field. CONSTITUTION:The output of a high frequency pulse generator 2 excites a coil 4 through an amplifier 3. The signal component received by the coil 4 is converted to the image by a signal processing device 7 through an amplifier 5 and a detector 6. The output of the generator 2 is made to the standard signal of a right angle phase detection by the detector 6. Gradient magnetic fields for Z direction and direction at right angle therewith are generated by coils 8-10, and said coils are driven by amplifiers 11-13. A coil 14 for generating static magnetic field is driven by an electric source 15. By setting the interval between 90 deg. and 180 deg. high frequency magnetic fields to the value near integer times of the period of the outer part vibrating magnetic field, the bad influence of the outer part vibrating magnetic field is decreased, and the image quality is improved. In this case, the frequency of the vibrating magnetic field is obtained by a Gauss meter 20 and a counter 21 having a sensor 19. |
