WO2014140996A1 - Garniture intercalaire pour système d'imagerie - Google Patents

Garniture intercalaire pour système d'imagerie Download PDF

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Publication number
WO2014140996A1
WO2014140996A1 PCT/IB2014/059440 IB2014059440W WO2014140996A1 WO 2014140996 A1 WO2014140996 A1 WO 2014140996A1 IB 2014059440 W IB2014059440 W IB 2014059440W WO 2014140996 A1 WO2014140996 A1 WO 2014140996A1
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WO
WIPO (PCT)
Prior art keywords
imaging system
expandable
elongate
support structure
insert
Prior art date
Application number
PCT/IB2014/059440
Other languages
English (en)
Inventor
Oliver Lips
Falk Uhlemann
Norbert Kuhn
Original Assignee
Koninklijke Philips N.V.
Philips Deutschland Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips N.V., Philips Deutschland Gmbh filed Critical Koninklijke Philips N.V.
Publication of WO2014140996A1 publication Critical patent/WO2014140996A1/fr

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Classifications

    • 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
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/385—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils
    • G01R33/3854—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils means for active and/or passive vibration damping or acoustical noise suppression in gradient magnet coil systems
    • 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
    • G01R33/4808—Multimodal MR, e.g. MR combined with positron emission tomography [PET], MR combined with ultrasound or MR combined with computed tomography [CT]
    • G01R33/481—MR combined with positron emission tomography [PET] or single photon emission computed tomography [SPECT]

Definitions

  • the invention relates to an insert for use in bore-based magnetic imaging systems.
  • the invention finds application in magnetic particle imaging systems and magnetic resonance imaging (MRI) imaging systems and is described with particular reference to the latter.
  • the invention may also be used in so-called combined imaging systems which combine MRI imaging with another imaging modality such as MRI-PET and MRI-SPECT.
  • Bore-based magnetic imaging systems such as MRI have a characteristic imaging region, or a bore, from which imaging data is acquired during an imaging session.
  • the bore comprises a radially enclosed region around which are disposed various coils necessary to the generation and detection of magnetic fields in the imaging process.
  • an MR imaging system typically comprises a patient bore, defined by a scanner housing, around which are disposed a body coil, gradient coils, and a main magnet surrounded by a cryogenic housing.
  • the cryogenic housing defines an outermost bore whose flanges typically provide the support for the various coils inserted therein.
  • an object to be imaged such as a human or animal is positioned in the patient bore by means of a subject trolley that is movable along the patient bore axis.
  • RF body coil for maintenance requires the removal of part of the scanner housing.
  • an additional or substitute RF body coil may be inserted within the patient bore, thus radially within the scanner housing.
  • the cryogenic housing bore's flanges, the patient bridge or table or additional structures may again provide support for the additional or substitute coil, and access to the coil is improved since removal of the scanner housing is no longer necessary.
  • magnetic imaging systems are combined with other imaging modalities, such as in a combined MRI-PET or an MRI-SPECT imaging system. In such combined imaging systems, imaging system components from a second imaging modality may likewise be disposed within the cryogenic housing bore.
  • Such components may be inserted within or positioned close to the cryogenic housing bore either radially beyond the scanner housing, or radially within the scanner housing.
  • the former configuration is exemplified by a combined MRI-PET imaging system having a common imaging region wherein PET imaging system components are inserted in a gap between axially-separated groups of gradient coils.
  • the latter configuration is exemplified by an MR imaging system having a removable PET insert and permits a more temporary configuration of the MR imaging system for MR-PET imaging.
  • RF body coils and imaging system components from a second imaging modality are supported by the scanner housing, the cryogenic housing or additional structures, and in other instances such components are supported and positioned within the imaging region by means of a patient trolley or table.
  • Such MR-PET inserts are used in both preclinical and clinical applications.
  • Inserts that are inserted both radially within and radially beyond the scanner housing in MRI and magnetic particle imaging systems suffer from a common problem of vibrations.
  • the vibrations may originate elsewhere in the imaging system.
  • currents in the gradient coils are acted upon by Lorentz forces. These cause the gradient coils to vibrate, typically at audio frequencies, which further causes an audible noise.
  • the noise is undesirable as it disturbs the subject in the imaging region, causing the subject to move and thereby degrade image quality.
  • a more fundamental consequence of such vibrations is however their impact upon the lifetime of imaging system components. These vibrations are communicated throughout the MR imaging system where they act to degrade the lifetime of imaging system components.
  • An inserted RF body coil is one imaging system component susceptible to lifetime
  • vibrations degradation from such vibrations.
  • the lifetimes of imaging system components from other imaging modalities that are inserted into the MR imaging system bore such as PET and SPECT imaging system components, are likewise susceptible to degradation from such vibrations. Such vibrations may furthermore may lead to image quality degradation.
  • Patent application US2012/0313643 Al discloses an adjustable vibration damping suspension system arranged between a gradient winding assembly of an MRI device and a support structure supported by a primary magnet assembly of an MRI device.
  • the adjustable vibration damping system includes a plurality of separately inflatable support elements.
  • the imaging system insert comprises an elongate support structure and an expandable cushion.
  • the elongate support structure has an outer circumference and the expandable cushion surrounds the outer circumference of the elongate support structure.
  • the expandable cushion surrounds the elongate support structure, radial forces are applied to the elongate support structure from all radial angles which act to provide substantially uniform damping around all radial angles, thereby improving the damping of the elongate support structure.
  • an RF body coil, or imaging system components from other imaging modalities such as a PET or SPECT are supported by insert, the transfer of vibrations from for example the gradient coil to these components is reduced.
  • the expandable cushion surrounds the elongate support structure it acts to centre the insert in the bore into which it is inserted, thereby removing the need for its alignment with the imaging system bore, thereby simplifying the assembly and easing the reconfiguration of the imaging system.
  • the expandable cushion surrounds the elongate support structure it acts to axially bound the region between the elongate support structure and the bore into which it is inserted, thereby reducing the axial radiation of sound propagating in the region between the elongate support structure and the bore.
  • the thermal resistance presented to imaging system components attached to the elongate support cushion is increased.
  • imaging system components such as an RF body coil and a PET or a SPECT detector module, but not by high current carrying imaging system components that dissipate significant heat such as a gradient field coil.
  • the length of the expandable cushion in a direction parallel to the imaging system insert longitudinal axis is at least one third of the longitudinal length of the imaging system insert.
  • the length of the expandable cushion is very short its axial position affects the support it provides to the elongate support structure. When its length exceeds this length, improved support for the imaging system insert is achieved.
  • An upper limit to the expandable cushion length is approximately that of the imaging system insert.
  • the imaging system insert further comprises a sealed compartment having a gas-impermeable wall which surrounds a void.
  • the pressure in the void is below standard atmospheric pressure of 1013 millibars.
  • the sealed compartment forms part of the elongate support structure.
  • Such an arrangement provides a more compact imaging system insert.
  • an imaging system having a bore and an imaging system insert.
  • the insert has at least two expandable cushions which surround the elongate support structure and are separated axially by a distance.
  • the distance is preferably approximately the length of elongate support structure less the combined width of the cushions, and preferably exceeds one third of the length of the elongate support structure in order to adequately support it and prevent it from pivoting about its centre.
  • the elongate support structure has a gas-impermeable wall having an outer circumference defined by a surface of revolution about the imaging system insert longitudinal axis. Furthermore the cushions axially bound a sealed volume which is formed in the region between the wall and the imaging system bore.
  • the gas-impermeable wall improves the sound isolation of the elongate support structure.
  • Such an elongate support structure can be used to support imaging system components such as an RF coil, a PET detector array, or a SPECT detector array within the bore of an imaging system with improved vibration damping.
  • the pressure in the sealed volume is less than standard atmospheric pressure, thus less than 1013 millibars.
  • the partially- evacuated sealed volume provided by the gas-impermeable wall further improves the sound isolation of the elongate support structure, advantageously reducing the acoustic transfer of vibrations from the imaging system bore to the elongate support structure.
  • an elongate cradle is disposed within the inner circumference of the elongate support structure.
  • the elongate cradle is held in this position by an inner expandable cushion which surrounds the elongate cradle, and the cushion is disposed between the elongate cradle and the elongate support structure.
  • Such an elongate cradle provides, in addition to the elongate support structure, a second structure for supporting imaging system components from a second imaging system within the bore of an imaging system.
  • an imaging system insert is provided which may for example have an elongate support structure which supports an RF body coil, and within this is an elongate cradle that supports a PET or a SPECT detector array.
  • the length of an inner expandable cushion in a direction parallel to the elongate cradle longitudinal axis is at least one third of the longitudinal length of the elongate cradle.
  • the length of the inner expandable cushion is very short its axial position affects the support it provides to the elongate cradle.
  • its length exceeds this length improved support for the elongate cradle is achieved.
  • An upper limit to the expandable cushion length is approximately that of the elongate cradle.
  • an elongate support structure and an elongate cradle wherein two inner cushions are disposed between the elongate cradle and the elongate support structure.
  • the inner cushions are separated axially along the elongate cradle longitudinal axis by a distance.
  • the distance is preferably approximately the length of elongate cradle less the combined width of the cushions, and preferably exceeds one third of the length of the elongate cradle in order to adequately support it without it pivoting about its centre.
  • the inner expandable cushions are in an expanded state in order to retain the elongate cradle within the elongate support structure.
  • both the elongate cradle and the elongate support structure each have a gas impermeable wall.
  • the cushions axially bound a sealed volume which is formed in the region between the cradle wall and the support structure wall. This improves the sound isolation of the elongate cradle.
  • Such an elongate cradle can be used to retain various imaging system components such as an RF coil, a PET detector array, or a SPECT detector array within the bore of an imaging system with improved vibration isolation owing to the increased acoustic impedance presented by the gas impermeable wall.
  • the pressure in the sealed volume is less than standard atmospheric pressure, thus less than 1013 millibars.
  • the partially- evacuated sealed volume provided in the region between the walls of the elongate cradle and the elongate support structure increases the sound isolation of the elongate cradle, advantageously reducing the acoustic transfer of vibrations to the elongate cradle.
  • a gas valve in communication with a sealed volume is provided. Furthermore, means for achieving a pressure in the sealed volume that is lower than standard atmospheric pressure are provided. In so doing the pressure in a sealed volume may be controlled, for example to compensate for minor leaks, or to adjust the damping constant by controlling the pressure in the sealed volume in order to improve damping at particular resonant frequencies.
  • Suitable means include vacuum tubing in communication with a vacuum pump and a vent valve. Preferably such a vacuum pump and vent valve is disposed beyond the bore of the imaging system.
  • either the elongate support structure or the elongate cradle includes one or more of the following: a PET detector array, a SPECT detector array, an RF body coil.
  • an expandable cushion has an expanded state and a contracted state.
  • the area of the cross section of the expandable cushion in a plane that is perpendicular to the imaging system insert longitudinal axis, exceeds the area of the cross section in the contracted state.
  • the cushion may be used to retain either the elongate support structure or the elongate cradle.
  • the pressure in the cushion causes a part outer surface of the cushion to make contact between the imaging system bore and the elongate support structure, or between the elongate support structure and the elongate cradle. Furthermore a gas-tight seal may thereby be created.
  • an expandable cushion comprises an expandable membrane that is impermeable to gas and fluid.
  • the membrane envelops an inner region which contains a gas or fluid.
  • the gas or fluid is in common communication with the inner surface of the expandable membrane. In so doing the gas or fluid applies the same pressure throughout the inner region, thereby acting to centre the cradle or support structure supported by the cushion.
  • an expandable cushion has a plurality of protrusions which are fixed to an inner surface of the expandable membrane. Such protrusions prevent the total collapse of the cushion due to the weight of the elongate cradle or the elongate support structure it supports.
  • Figure 1 illustrates some of the components associated with the main magnet of an MR imaging system.
  • Figure 2 illustrates a first embodiment of an imaging system insert in accordance with some aspects of the invention.
  • Figure 3 illustrates a second embodiment of an imaging system insert in accordance with some aspects of the invention.
  • Figure 4 illustrates a third embodiment of an imaging system insert in accordance with some aspects of the invention.
  • Figure 5 illustrates a fourth embodiment of an imaging system insert in accordance with some aspects of the invention.
  • Figure 6 illustrates a fifth embodiment of an imaging system insert in accordance with some aspects of the invention.
  • an imaging system insert comprising an elongate support structure and an expandable cushion.
  • the elongate support structure has an outer
  • the expandable cushion surrounds the outer circumference of the elongate support structure.
  • the invention is described with reference to an MR imaging system although it is to be appreciated that the invention also finds application in magnetic particle imaging systems.
  • FIG. 1 illustrates some of the components associated with the main magnet of an MR imaging system.
  • MR imaging system 1 comprises scanner housing 2 which defines a patient bore 3 having an imaging region 4 within which a subject to be imaged such as a human or animal may be located.
  • a main magnet 5 surrounded by cryogenic housing 6 generates a main magnetic field in imaging region 4.
  • Cryogenic housing 6 defines a cryogenic housing bore 7 within which various coils are inserted.
  • Magnetic gradient field coils 8 are arranged on or in the scanner housing 2 to generate additional magnetic fields to superimpose upon the main magnetic field in imaging region 4.
  • the magnetic gradient field coils 8 typically include coils for producing three orthogonal magnetic field gradients.
  • a whole-body RF coil 9 with an RF screen 10 is arranged in or on the housing 2 in order to inject RF excitation pulses into the imaging region 4.
  • local coils not shown are used to inject RF pulses local to the subject being imaged.
  • an RF transmitter is coupled to the whole body RF coil 9 via RF switching circuitry or coupled to one or more local coils not shown to generate magnetic resonances in a region of the imaging region 4.
  • a gradients controller controls the signals to magnetic gradient field coils 8 in order to spatially encode the magnetic resonances.
  • a one-dimensional magnetic field gradient applied during radio frequency excitation produces slice-sensitive excitation; magnetic field gradients applied between excitation and readout of magnetic resonances provide phase encoding, and magnetic field gradients applied during readout of magnetic of magnetic resonances provide frequency encoding.
  • the MRI pulse sequences can be configured to produce Cartesian, radial or other spatial encodings.
  • the RF switching circuitry After the RF excitation the RF switching circuitry operatively disconnects the RF transmitter and connects an RF receiver to the whole body RF coil 9 to acquire spatially- encoded magnetic resonances from within the imaging region 4. Alternatively the RF receiver is connected to one or more of the local coils not shown.
  • the acquired magnetic resonances are stored in an MRI data buffer and are reconstructed by an MRI reconstruction processor.
  • the MRI reconstruction processor uses algorithms such as Fast Fourier Transform (FFT) reconstruction algorithms when Cartesian encoding is used.
  • FFT Fast Fourier Transform
  • cryogenic housing bore 7 provides support for the gradient and RF body coils, the coils being separated from imaging region 4 by scanner housing 2. In this configuration, access to the RF body coil for maintenance purposes requires the removal of part of the scanner housing.
  • an additional or substitute RF body coil may be inserted radially within patient bore 3.
  • cryogenic housing bore 7 again provides the support for this additional or substitute coil and access to the coil is improved since removal of the scanner housing is no longer necessary.
  • Such an RF body coil may be fixed to the inner surface of scanner housing 2.
  • an MR imaging system may be combined with other imaging modalities to provide combined MR-PET or MR-SPECT imaging capability.
  • imaging system components from a second imaging modality such as radiation detectors may likewise be disposed within the cryogenic housing bore 7.
  • imaging system components may be mounted to a fixture and inserted within the cryogenic housing bore 7 either radially beyond or radially within patient bore 3 defined by scanner housing 2.
  • the former configuration include combined MR-PET imaging systems having a common imaging region in which the PET detectors of the PET imaging system are inserted axially between the two groups of axially-separated gradient coils.
  • the latter configuration permits the temporarily reconfiguration of an MR imaging system as for example a MR-PET imaging system.
  • an RF body coil or imaging system components from a second imaging modality are supported by the scanner housing, which is in turn supported by the cryogenic housing bore, and in other instances such components are supported and positioned within the imaging region by means of a patient trolley.
  • the present invention provides an imaging system insert for use in a magnetic imaging system with improved vibration isolation.
  • the insert comprises an elongate support structure and an expandable cushion.
  • the elongate support structure has an outer
  • the insert may be inserted into a bore of an imaging system, for example into a bore of the MR imaging system illustrated in Figure 1.
  • Various imaging system components may be attached to the imaging system insert in order protect such components from vibrations generated elsewhere in the imaging system.
  • Figure 2 illustrates a first embodiment of an imaging system insert in accordance with some aspects of the invention.
  • the embodiment of Figure 2 may be used in the MR imaging system illustrated in Figure 1.
  • imaging system insert 21 having longitudinal axis 22 is shown.
  • a cross section of the insert in a plane perpendicular to the imaging system insert longitudinal axis 22 is also shown.
  • Imaging system insert 21 comprises elongate support structure 23 having outer circumference 24 facing radially away from imaging system insert longitudinal axis 22, and an expandable cushion 25 which surrounds outer circumference 24 of elongate support structure 23.
  • imaging system insert 21 may be inserted within an imaging system bore 12, such as a bore of the MR imaging system illustrated in Figure 1.
  • Expandable cushion 25 has an expanded state and a contracted state wherein the area of the cross section of the expandable cushion in a plane perpendicular to the imaging system longitudinal axis in the expanded state exceeds the area of the cross section of the expandable cushion in the contracted state.
  • expandable cushion 25 may be in the contracted state.
  • expandable cushion 12 When positioned within an imaging system bore 12, expandable cushion 12 may subsequently be in the expanded state in which expandable cushion 25 makes contact with both a portion of the imaging system bore 12 as well as with a portion of the outer circumference 24 of elongate support structure 23 such that radial forces are applied to the imaging system insert in order to retain the insert within the bore. Damping of vibrations is provided by expandable cushion 25 which provides a spring constant in all radial directions to imaging system insert longitudinal axis 22.
  • the insert in Figure 2 may in general be inserted within any imaging system bore that is capable of supporting its weight, in combination with that of any imaging system components attached thereto.
  • the cryogenic housing bore 7 has sufficient mechanical strength to either directly support imaging system insert 21, or indirectly do so by means of an intermediate mechanical coupling such as a support strut.
  • Such a bore includes for example a patient bore as well as any other bore within the imaging system.
  • imaging system bore 12 in Figure 2 may therefore correspond to any bore within cryogenic housing bore 7, thus expandable cushion 25 may be in direct contact with cryogenic housing bore 7, or alternatively expandable cushion 25 may be in direct contact with patient bore 3, or indeed any bore between these extremes.
  • the imaging system insert 21 may be inserted within a bore having a mechanical coupling to the ground that is independent to that of cryogenic housing bore 7, thus via for example an independent supporting frame. In this latter example, even further improved vibration isolation is achieved through the mechanical decoupling of the MR imaging system and the insert.
  • elongate support structure 23 is illustrated as having a surface of rotation about the imaging system insert longitudinal axis 22.
  • the cross section through elongate support structure 23 in a plane perpendicular to imaging system insert longitudinal axis 22 is circular as illustrated; however other surfaces of rotation are also suitable.
  • a modification to the shape of the rotated surface may assist in the fixing of imaging system components thereto.
  • elongate support structure 23 may comprise a frame in which no surface of rotation is present at all.
  • a suitable frame includes an arrangement of struts aligned with the imaging system longitudinal axis 22, wherein the struts are held in positions circumferential to the axis by supports located at each end of the elongate support structure.
  • a cross section through the imaging system insert perpendicular to the longitudinal axis may have an oval or a polygonal outer circumference with gaps between the longitudinally-aligned struts, the elongate support structure being surrounded by an expandable cushion.
  • Imaging system components specific to MRI, such as an RF body coil, as well as imaging system components from a second imaging modality such as a PET detector or a SPECT detector may be fixed to the elongate support structure 23 in Figure 2 in order to isolate these components from vibrations and thereby improve their lifetime.
  • Figure 2 illustrates an imaging system component 26 which may optionally be fixed to elongate support structure 23 in this manner. Improved vibration isolation of the imaging system component is provided by expandable cushion 25 in Figure 2 which acts to damp the communication of vibrations between the imaging system bore 12 and the elongate support structure 12.
  • Expandable cushion 25 provides improved damping because it surrounds the elongate support structure 23, thereby providing a spring constant having radially-opposing forces applied from all radial angles which provides substantially uniform radial vibration damping.
  • an imaging system component 26 may be disposed between the struts and held in place by the struts.
  • the struts may be advantageously used to form supports for a coil, such as an RF body coil.
  • expandable cushion 25 Further advantages arising from the embodiment described in Figure 2 arising from expandable cushion 25 include simplified assembly. Since the expandable cushion surrounds elongate support structure 23 it acts to centre the insert in the imaging system bore 12 into which it is inserted, thereby removing the need for its alignment with the imaging system bore. Repeatable alignment of the imaging system results in reduced time in assembling and reconfiguring the imaging system. The ability to locate the insert within the bore of the imaging system further improves access and reduces reconfiguration time.
  • the expandable cushion surrounds the elongate support structure it acts to axially bound the region between the insert and the bore into which it is inserted, thereby reducing the axial radiation of sound propagating in the region between the elongate support structure and the bore into which it is inserted.
  • expandable cushion 25 in Figure 2 comprises an expandable membrane which envelops an inner region wherein the membrane is
  • the inner region contains a gas or fluid.
  • the inner region preferably contains a gas such that the expandable cushion may be expanded and contracted by changing the gas pressure within the membrane.
  • the pressure in such an inflatable cushion may be controlled using gas-communicating tubing which connect with an air pump and air extraction valve disposed beyond the imaging region.
  • a pressure control unit may be in pressurable communication with the expandable cushion for controlling the pressure therein.
  • the expandable cushion may further have a valve used in controlling the pressure in the cushion.
  • the inner region may comprise a single continuous volume such that gas or fluid is in common communication with the inner surface of the membrane.
  • the length of expandable cushion 25 is substantially the same as that of the elongate support structure in a direction parallel to the imaging system insert longitudinal axis 22 in order to provide good axial support for the elongate support structure. Adequate support is provided when the length of the cushion exceeds approximately half the length of the elongate support structure 23.
  • the expandable cushion may contain protrusions disposed on the inner surface of the membrane which are located radially about the imaging system's longitudinal axis. Such protrusions may be formed from the same material as the cushion and act to limit the compressibility of the expandable cushion, thereby limiting the extent movement of the elongate structure during its vibration.
  • the inner region of expandable cushion 25 in Figure 2 contains a fluid
  • similar pumping means, valve means and pressure control means may be used in place of the air means in order to control the volume and pressure of fluid in the expandable cushion.
  • the effective spring constant provided by the expandable cushion is a combination of the spring constant of the expandable membrane and that of the gas or fluid therein. Fluid has the advantage of reduced compressibility as compared to gas and its higher spring constant may thus be used to provide a larger effective spring constant radially about the elongate support structure. A higher spring constant may thus provide improved vibration isolation, in particular for higher vibration frequencies. Furthermore the reduced compressibility of a fluid may provide more stable retention of the elongate support structure within imaging system bore 12.
  • Suitable materials for the expandable membrane of the expandable cushion include polymers such as rubber, including but not limited to silicone rubber. Any gas, including but not limited to air or nitrogen may be used in the inner region of the expandable cushion. Any fluid, including but not limited to water and ethylene glycol may be used in the inner region of the expandable cushion.
  • Suitable materials for the elongate support structure include those having a low conductivity which may therefore be used in the MR imaging system bore, and further those materials having adequate strength to support any imaging system component 26 held in place by the elongate support structure. Suitable materials include fibreglass structures with an epoxy or a polyester resin, and carbon fiber.
  • vibration isolation of the elongate support structure may be achieved when a vacuum region is disposed between the source of vibrations and the region requiring isolation.
  • the dominant source of vibrational energy transfer in the described MR imaging system is by mechanical contact, some energy is transferred by propagating sound waves. Since a vacuum does not transfer sound energy, the use of a vacuum region may be used to reduce vibrational energy transfer.
  • a vacuum is preferable, a region having a gas at any pressure that is lower than the surrounding medium may also be used to prevent the transfer of sound vibrations to some degree.
  • Figure 3 illustrates a second embodiment of an imaging system insert in accordance with some aspects of the invention.
  • a cross section of the insert in a plane perpendicular to the imaging system insert longitudinal axis 22 is also shown.
  • Imaging system insert 3 lin Figure 3 may be used in the MR imaging system illustrated in Figure 1.
  • Figure 3 includes sealed compartment 32 which may be in contact with or fixed to outer circumference 32 of elongate support structure 23. When thus arranged the sealed compartment reduces the transfer of vibrational energy to elongate support structure 23.
  • Sealed compartment 32 may alternatively be arranged to be in contact with inner circumference 33 of elongate support structure 23 in order to likewise reduce vibrational energy transfer to the region within elongate support structure 23.
  • Sealed compartment 32 may have an annular shape as illustrated in Figure 3 wherein isolation is improved for a substantial portion of the circumference surface area of elongate support structure 23, or alternatively comprise a single, or a plurality of discrete compartments each covering only a portion of the
  • sealed compartment 32 has a gas-impermeable wall which surrounds a void.
  • the pressure in the void is below the ambient pressure surrounding the insert, thus below standard atmospheric pressure of 1013 millibars, in order to provide useful vibration isolation.
  • a pressure in the region of 1 millibars to 10 millibars is a useful compromise between the capabilities of pumping systems and the benefit in terms of improved vibration isolation.
  • sealed compartment 32 may form part of the elongate support structure, for example by forming the elongate support structure from two hollow concentric cylindrical members and sealing the region therebetween using two axially-separated an o-rings.
  • Figure 4 illustrates a third embodiment of an imaging system insert in accordance with some aspects of the invention.
  • a cross section of the insert in a plane perpendicular to the imaging system insert longitudinal axis 22 is also shown.
  • the embodiment of Figure 4 may be used in the MR imaging system illustrated in Figure 1.
  • Imaging system insert 41 in Figure 4 has two expandable cushions (25a, 25b) wherein each cushion surrounds outer circumference 24 of elongate support structure 23.
  • the cushions are separated axially along the imaging system insert longitudinal axis 22 by a distance 42.
  • the distance is preferably approximately the length of elongate support structure 23 less the combined width of the cushions, and preferably exceeds one third of the length of elongate support structure 23 in order to adequately support elongate support structure 23 without it pivoting about its centre.
  • elongate support structure 23 has a gas impermeable wall that may for example have its outer circumference 24 formed by a surface of rotation about imaging system insert longitudinal axis 22.
  • imaging system insert 41 may be inserted within an imaging system bore 12, such as a bore of the MR imaging system illustrated in Figure 1 with the expandable cushions in the expanded state such that elongate support structure 23 is retained within the bore. Imaging system insert 41 may for example be inserted within the patient bore of an MR imaging system.
  • the two expandable cushions 25a, 25b are in contact with both a portion of the imaging system bore and with a portion of the wall of elongate support structure 23 the two expandable cushions 25a, 25b are in an expanded state such that such that a sealed volume 44 is formed in the region between the wall and the imaging system bore; wherein sealed volume 44 is axially bounded by the two expandable cushions 25a, 25b.
  • the pressure in sealed volume 44 may be reduced to below the ambient pressure surrounding the insert, thus below standard atmospheric pressure of 1013 millibars.
  • a lower pressure in the sealed volume as compared to standard atmospheric pressure acts to further reduce the transfer of vibrational energy to or from elongate support structure 23, thereby improving the vibration isolation of the elongate support structure and prolonging the lifetime of any imaging system components 26 that may be connected thereto.
  • elongate support structure 23 includes gas valve 43 which is in communication with sealed volume 44 for controlling the pressure therein.
  • vacuum means may be in vacuumable communication with sealed volume 44 in order to extract gas therefrom and thereby achieve a pressure in sealed volume 44 that is lower than standard atmospheric pressure.
  • Figure 5 illustrates a fourth embodiment of an imaging system insert in accordance with some aspects of the invention.
  • a cross section of the insert in a plane perpendicular to the imaging system insert longitudinal axis 22 is also shown.
  • the embodiment of Figure 5 may be used in the MR imaging system illustrated in Figure 1.
  • imaging system insert 51 in Figure 5 includes elongate cradle 53 disposed within elongate support structure 23 and having elongate cradle longitudinal axis 52, which may be coaxially aligned with imaging system insert longitudinal axis 22, and an inner expandable cushion 55.
  • Elongate cradle 53 has an outer circumference 54 facing radially away from the elongate cradle longitudinal axis 52, and the second expandable cushion surrounds outer
  • imaging system insert 51 may be inserted within an imaging system bore, such as a bore in the MR imaging system illustrated in Figure 1.
  • Additional imaging system components 56 such as an RF body coil, a PET detector array, or a SPECT detector array may be in contact or fixed to elongate cradle 53 in order to isolate them, or other parts of the imaging system from vibrations.
  • the two expandable cushions provide improved vibration isolation and a means for positioning a second imaging system component 56 at a radially inner position relative to an imaging system component 26.
  • imaging system component 56 may correspond to an RF body coil
  • imaging system component 26 may correspond to a PET or a SPECT detector array such that the magnetic fields from the RF body coil within the imaging region are not disturbed by the array.
  • the self-centering of elongate cradle 53 within elongate support structure 23, and that of elongate support structure 23 within imaging system bore 12 provided by inner expandable cushion 55 and expandable cushion 25 respectively is particularly advantageous in repeatably and rapidly reconfiguring such a combined imaging system.
  • Figure 6 illustrates a fifth embodiment of an imaging system insert in accordance with some aspects of the invention. A cross section of the insert in a plane perpendicular to the imaging system insert longitudinal axis 22 is also shown.
  • imaging system insert 61 in Figure 6 includes elongate cradle 53 disposed within elongate support structure 23 and having elongate cradle longitudinal axis 52, which may be coaxially aligned with imaging system insert longitudinal axis 22. Imaging system insert 61 further includes two inner expandable cushions (65a, 65b) wherein each cushion surrounds outer
  • the cushions are separated axially along the elongate cradle longitudinal axis 52 by a distance 42.
  • the distance is preferably approximately the length of elongate cradle 53 less the combined width of the cushions, and preferably exceeds one third of the length of elongate cradle 53 in order to adequately support elongate cradle 53 without it pivoting about its centre. Additional cushions may be added in the same way.
  • Elongate cradle 53 has a gas impermeable wall that may for example have its outer circumference 54 formed by a surface of rotation about elongate cradle longitudinal axis 52.
  • imaging system insert 61 may be inserted within an imaging system bore, such as a bore in the MR imaging system illustrated in Figure 1.
  • Additional imaging system components 56 such as an RF body coil, a PET detector array, or a SPECT detector array may be in contact or fixed to elongate cradle 53 in order to isolate them from vibrations.
  • the two inner expandable cushions provide improved vibration isolation and the opportunity to locate a second imaging system component 56 at a radially inner position relative to an imaging system component 26.
  • Such a configuration is advantageous in a MR-PET imaging system where for example imaging system
  • imaging system component 26 may correspond to a PET or a SPECT detector array.
  • the self-centering of elongate cradle 53 within elongate support structure 23, and that of elongate support structure 23 within imaging system bore 12 provided by inner expandable cushions 65a, 65b, and by expandable cushions 25a, 25b is particularly advantageous in repeatably and rapidly reconfiguring such a combined imaging system.
  • each of the two inner expandable cushions 65a, 65b are in contact with both a portion of the outer circumference of elongate cradle 54 of elongate cradle and with a portion of inner circumference 33 of elongate support structure 23 and the two inner expandable cushions 65a, 65b are in an expanded state such that a sealed volume 66 is formed in the region between the elongate cradle wall 54 and the inner circumference 33 of elongate support structure 23; wherein sealed volume 66 is axially bounded by the two or more inner expandable cushions 65a, 65b.
  • the pressure in sealed volume 66 may be reduced to below the ambient pressure surrounding the insert, thus below standard atmospheric pressure of 1013 millibars.
  • elongate cradle 53 includes gas valve 63 which is in communication with sealed volume 66 for controlling the pressure in the sealed volume.
  • gas valve 63 which is in communication with sealed volume 66 for controlling the pressure in the sealed volume.
  • vacuum means may be in vacuumable communication with sealed volume 66 in order to extract gas therefrom and thereby achieve a pressure in sealed volume 66 that is lower than standard atmospheric pressure.
  • the imaging system insert has a longitudinal axis and the imaging system insert comprises an elongate support structure with an outer circumference facing radially away from the imaging system insert longitudinal axis.
  • the imaging system insert also has at least one expandable cushion which surrounds the outer circumference of the elongate support structure.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Pulmonology (AREA)
  • Radiology & Medical Imaging (AREA)
  • Theoretical Computer Science (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Abstract

L'invention concerne une garniture intercalaire destinée à un système d'imagerie magnétique à base d'alésage tel qu'un système d'imagerie par résonance magnétique. Cette garniture intercalaire comprend une structure support de forme allongée et un coussin expansible qui entoure le pourtour extérieur de la structure support de forme allongée et qui assure une isolation contre les vibrations. La garniture intercalaire s'utilise disposée à l'intérieur d'un alésage d'un système d'imagerie, le coussin expansible étant en état expansé de façon que la garniture intercalaire soit supportée par l'alésage.
PCT/IB2014/059440 2013-03-13 2014-03-05 Garniture intercalaire pour système d'imagerie WO2014140996A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3715894A1 (fr) * 2019-03-28 2020-09-30 Koninklijke Philips N.V. Bouclier acoustique pour un assemblage d'un aimant d'imagerie par résonance magnétique
WO2020193389A1 (fr) * 2019-03-28 2020-10-01 Koninklijke Philips N.V. Écran acoustique pour ensemble d'aimant d'imagerie par résonance magnétique
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