Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
  • H03H1/00—Constructional details of impedance networks whose electrical mode of operation is not specified or applicable to more than one type of network
  • H03H1/0007—Constructional details of impedance networks whose electrical mode of operation is not specified or applicable to more than one type of network of radio frequency interference filters
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R33/00—Arrangements or instruments for measuring magnetic variables
  • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
  • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
  • G01R33/48—NMR imaging systems
  • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
  • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
  • G01R33/567—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution gated by physiological signals, i.e. synchronization of acquired MR data with periodical motion of an object of interest, e.g. monitoring or triggering system for cardiac or respiratory gating
  • G01R33/5673—Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker

Definitions

• the present invention relates to the field of electronics, and more particularly that of filtering disruptive radiofrequency radiation, and relates to a device for filtering parasitic radio frequency emissions.
• the invention can in particular be implemented at the level of a monitor for monitoring the vital physiological parameters of a patient, intended to operate in the immediate vicinity and, more particularly, in the shielded enclosure, with respect to radiation.
• electromagnetic of a nuclear magnetic resonance imager.
• each monitoring module has inside said monitor is surrounded by a shielded box 30 and the monitor itself is delimited by a shielded box containing all of said modules.
• each monitoring module is linked, via one or more wires of connection, to a corresponding sensor placed on the patient outside said monitor.
• connection wires pass through these connection wires and are re-emitted at the level of the sensors placed in the electromagnetic environment for exploring the magnetic resonance imager, thus interfering, in particular with the magnetic field. oscillating at high frequency generated by said imager.
• the problem posed by the present invention therefore consists in producing a device having a simple structure and making it possible to carry out effective filtering at the level of the connection wires of the sensors so as to prevent pollution of the electromagnetic environment. .
• the subject of the present invention is a device for filtering radiated frequency emissions, particularly at the level of the connection wires of the sensors of an armored surveillance monitor placed in an electromagnetic environment sensitive in particular to radiofrequency emissions. of said monitor, characterized in that each connection wire is connected, individually, to the monitoring module corresponding to the sensor considered and placed inside said monitor, by means of at least one filter unit arranged in a shielded housing forming a Faraday cage.
• FIG. 1 is a schematic sectional view of the filtering device according to the invention
• FIG. 2 is a representation schematic of the filtering device of Figure 1, mounted in a monitoring monitor.
• each connection wire 2 is connected, individually, to the monitoring module corresponding to the sensor considered and placed inside the surveillance monitor, by the intermediary of at least one filtering unit 3, 3 'disposed in a shielded housing 4, 4' forming a Faraday cage.
• the shielded boxes 4, 4 ′ the embodiment of which is known in itself, thus make it possible to isolate them and to filter, independently of one another, the various connection wires 2 of the sensors used.
• the filtering device 1 is preferably constituted by two filtering units 3 and 3 ′ in low cascade, for each connection wire 2, each arranged in a housing 4, 4 ′ corresponding and presenting together an attenuation of at least 70 decibels in the range of working frequencies of a resonance imager, that is to say, for the frequencies included, generally between 10 MHz and 100 MHz.
• the filter device 1 constitutes an interface between the connection wires 2 coming from the sensors and the wires 2 'for internal connection in the surveillance monitor, said filtering device 1 being furthermore provided with input and output connectors, adapted to the connectors of the corresponding wires 2 or 2'.
• the shielded boxes 4 and 4 ′ surrounding the filtering units 3 and 3 ′ are advantageously produced in an electrically continuous manner with the Faraday cage 5 of the surveillance monitor.
• These shielded boxes 4, 4 ′ therefore provide, simultaneously, on the one hand, the electromagnetic shielding of each of the different transmission channels or channels 3, 3 ′ of the filtering device 1 with respect to the other channels or channels of the latter and vis-à-vis the outside (vertical partition in Figure 1) and, on the other hand, the electromagnetic shielding that, for each channel or transmission channel 3, 3 ', of the two units filtering cascade 3 and 3 'between them (horizontal partition in Figure 1).
• the first filter unit 3 contains a coil L2 and the second filter unit 3 'contains a low-pass filter L2 , Cl in series with a low pass filter L3, C2.
• the three coils L1, L2 and L3 have, respectively, electrical inductance values of approximately l ⁇ H, 100 mH and LttH, the two capacitors Cl and C2 each having a capacitance value about 50 nF.
• the invention it is therefore possible to produce a filtering device allowing in particular to attenuate the parasitic radiofrequency emissions tran ⁇ located in the connection wires of the sensors to the monitoring monitor, so that their power is less than a threshold value acceptable for the electromagnetic environment.

Landscapes

• Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Physiology (AREA)
• Biophysics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Power Engineering (AREA)
• Pulmonology (AREA)
• General Health & Medical Sciences (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Radiology & Medical Imaging (AREA)
• Signal Processing (AREA)
• Cardiology (AREA)
• High Energy & Nuclear Physics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
• Magnetic Resonance Imaging Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=9425543

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Cited By (1)

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• 1992
  • 1992-01-08 FR FR9200234A patent/FR2685989A1/fr active Granted
• 1993
  • 1993-01-07 WO PCT/FR1993/000010 patent/WO1993014565A1/fr not_active Ceased

Non-Patent Citations (3)

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