摘要:
A technique is provided to reserve large examination space in the tunnel type MRI apparatus, without increasing production cost nor reducing significantly irradiation efficiency and homogeneity in an irradiation distribution within an imaging region. The present invention provides an RF coil unit in which four partial cylindrical coils are placed with a gap therebetween in the circumferential direction inside a cylindrical RF shield, in such a manner that two pairs of the partial cylindrical coils are opposed to each other, and magnetic fields produced by the individual partial cylindrical coils are combined, thereby producing a circularly polarized wave field or an elliptically polarized wave field. The partial cylindrical coil is provided with a partial cylindrical conductor, multiple first conductors substantially parallel with the central axis of the RF shield, multiple capacitors connecting both ends of the first conductors with the partial cylindrical conductor, and a second conductor adjacent to at least one of the ends of the first conductor. The partial cylindrical coils are respectively provided with high frequency signals having a desired amplitude ratio and phase difference, while a reference frequency thereof being identical.
摘要:
There is provided a technique for securing a large examination space in a tunnel type MRI device without inviting increase of manufacturing cost and without significantly reducing irradiation efficiency or uniformity of the irradiation intensity distribution in an imaging region. Between rungs of a partially cylindrical RF coil, which coil corresponds to a cylindrical RF coil of which part is removed, there are disposed half-loops generating magnetic fields, which are synthesized with magnetic fields generated by loops constituted by adjacent rungs of the partially cylindrical RF coil and rings connecting the rungs to generate a circularly polarized or elliptically polarized magnetic field. Further, high-frequency signals of the same reference frequency having a desired amplitude ratio and phase difference are supplied to the partially cylindrical RF coils and half-loops.
摘要:
In an imaging according to the step moving method, a slice imaging condition with respect to each station is optimized, thereby enabling an efficient imaging. A controller of an MRI apparatus displays positioning frames 601 to 606, and operation handles 607 and 608 thereof, in order to set a slice imaging condition at every various positions (stations) of a table on which a test object is mounted. By manipulating the positioning frames and the operation handles via I/O unit, the slice imaging condition is set. According to this slice imaging condition, imaging at each station position of the table is executed.
摘要:
In order to improve image quality in MRI using an EPI method without extending imaging time excessively, reference data is acquired in the absence of substantial phase encoding gradients by using an EPI sequence in combination with an echo shift (ETS) method, at times related to the timing of echo signals for image data. The reference data is used for phase correcting the image data acquired with application of phase encoding. The reference data can be measured for a single shot, or a few shots, and used to estimate reference data for the rest of the shots in which imaging data is acquired.
摘要:
An MRI apparatus and method in which image data is produced using NMR signals obtained in plural measurements performed at different times respectively. Data is calculated indicating temperature distribution within the object for image data of each measurement time and spatial discontinuity of the calculated temperature distribution data is corrected. Temperature change distribution within the object between different measurement times is calculated by subtracting the corrected temperature distribution data of each measurement time, and the calculated temperature change distribution is transformed to indicative data for supply to a display for display.
摘要:
A probe for an MRI apparatus in a vertical magnetic field system including: an array coil which is formed by arranging a plurality of unit coils, which can be driven independently of one another, in a direction perpendicularly intersecting a direction of a static magnetic field; and a compensating coil which forms a magnetic field in a direction perpendicularly intersecting both a direction of a magnetic field formed by the array coil and the direction of the magnetic field, a signal detected by the array coil and a signal detected by the compensating coil being composed so as to be in phase with each other, thereby to be outputted.
摘要:
A probe for an MRI apparatus in a vertical magnetic field system including: an array coil which is formed by arranging a plurality of unit coils, which can be driven independently of one another, in a direction perpendicularly intersecting a direction of a static magnetic field; and a compensating coil which forms a magnetic field in a direction perpendicularly intersecting both a direction of a magnetic field formed by the array coil and the direction of the magnetic field, a signal detected by the array coil and a signal detected by the compensating coil being composed so as to be in phase with each other, thereby to be outputted.
摘要:
A nuclear magnetic resonance apparatus receives nuclear magnetic resonance signals from an object under test with an RF probe which is an array of coils, implements down-frequency conversion with frequency converters for the received signals in multiple channels such that the frequency bands of the converted signals do not virtually overlap, filters the converted signals with band pass filters each operating to cut off frequency bands of other channels, hybridizes the filtered signals of multiple channels to form a hybridized signal, and produces an image from the hybridized signal.
摘要:
A projection detecting apparatus for use in a third generation X-ray computer tomography includes an X-ray source and a detector array both mounted on a rotatable gantry for detecting X-ray projections of an object under inspection sequentially at a plurality of angles of the gantry, respectively. The detector array is formed by disposing consecutively a plurality of detector element blocks each constituted by a photodiode array and a scintillator array laminated together. The element blocks are so disposed as to be asymmetric to the center line of a fan-like radiation beam which line extends through the position of the X-ray source and the center of rotation of the gantry.
摘要:
A radiation imaging sensor including laminate structure of a phosphorescent layer, a light-transmissive electrode, a photoconductor layer, an insulating layer and an electrode, an applied voltage to the photoconductor layer through the light-transmissive electrode and the electrode is increased sufficiently so that light emitted from the phosphorescent member causes avalanche multiplicaton of the electrons and/or positive holes generated in the photoconductor layer by field sweep inside the photoconductor layer.